Provided by: atop_2.11.1-3_amd64 
NAME
atop - Advanced System & Process Monitor
SYNOPSIS
Live measurement in bar graph mode:
atop -B[H] [-t [absdir]] [interval [samples]]
Live measurement cgroups in text mode:
atop -G [-t [absdir]] [-2|-3|-4|-5|-6|-7|-8|-9] [-a] [-C|-M|-D|-A] [interval [samples]]
Live measurement processes in text mode:
atop [-t [absdir]] [-g|-m|-d|-n|-u|-p|-s|-c|-v|-o|-y|-Y] [-C|-M|-D|-N|-A] [-fFX1xR] [interval
[samples]]
Live generation of parsable output (white-space separated or JSON):
atop [-Plabel[,label]... [-Z]] [-Jlabel[,label]...] [interval [samples]]
Write raw log files:
atop -w rawfile [-a] [-S] [interval [samples]]
Analyze raw log files in bar graph mode:
atop -B[H] -r [rawfile|yyy...] [-b [YYYYMMDD]hhmm[ss]] [-e [YYYYMMDD]hhmm[ss]]
Analyze cgroups from raw log files in text mode:
atop -G [-2|-3|-4|-5|-6|-7|-8|-9] [-a] -r [rawfile|yyy...] [-b [YYYYMMDD]hhmm[ss]] [-e
[YYYYMMDD]hhmm[ss]]
Analyze processes from raw log files in text mode:
atop -r [rawfile|yyy...] [-b [YYYYMMDD]hhmm[ss]] [-e [YYYYMMDD]hhmm[ss]]
[-g|-m|-d|-n|-u|-p|-s|-c|-v|-o|-y|-Y] [-C|-M|-D|-N|-A] [-fFX1xR]
Generate parsable output from raw log files (white-space separated or JSON):
atop -r [rawfile|yyy...] [-b [YYYYMMDD]hhmm[ss]] [-e [YYYYMMDD]hhmm[ss]] [-Plabel[,label]... [-Z]]
[-Jlabel[,label]...]
DESCRIPTION
The program atop is an interactive monitor to view the load on a Linux system. Every interval seconds
(default: 10 seconds) information is gathered about the resource occupation on system level (CPUs,
memory, disks and network interfaces) and on cgroup level (version 2). Besides, information is gathered
about the processes and threads that are responsible for the utilization of the CPUs, memory and disks.
Network load per process is shown only when the netatop kernel module or the netatop-bpf BPF module has
been installed.
TWIN MODE
With the -t flag you can run atop interactively in 'twin mode'. This mode allows to run a live
measurement with the possibility to review and analyze an earlier sample. Meanwhile, the live measurement
continues.
When started in twin mode, atop spawns a child process that gathers the counters and writes them to a
temporary raw file. The parent process reads the counters from the temporary raw file and presents them
to the user. The reading of the parent process keeps in pace with the written samples of the child
process for live measurements.
While the gathering continues by the child process, key 'r', key 'b' or key 'T' can be pressed to review
earlier samples. The parent process implicitly pauses the live measurement by pressing one of these keys
or by pressing key 'z' (pause) explicitly.
After browsing through the earlier samples with the keys 't' (next sample), 'T' (previous sample), 'r'
(reset to begin of measurement) and 'b' (branch to time tamp), the live measurement can be continued by
pressing key 'z' (resume after pause).
The temporary raw file will be written in the /tmp directory by default. Optionally the absolute path
name of an alternative directory can be added behind the -t flag (e.g. when there is not enough space in
the /tmp directory). In any case, the parent process will terminate the child process when the
measurement is finished and the temporary raw file will be removed.
BAR GRAPH MODE
When running atop you can choose to view the system load in bar graph mode or in text mode. In bar graph
mode the resource utilization of CPUs, memory, disks and network interfaces is shown via (character-
based) bar graphs, but only on system level. When you want to view more detailed information on system
level or when you want to view the resource consumption on process or thread level, you can switch to
text mode by pressing the 'B' key. Alternatively, you can use the 'B' key (again) to switch from text
mode to bar graph mode.
By default, atop starts in text mode unless the -B flag is used or unless 'B' has been configured as a
default flag in the .atoprc file (for further information about default flags, refer to the atoprc man
page).
In bar graph mode the terminal will be subdivided into four character-based windows, i.e. one window for
each hardware resource:
Processors
The first bar shows the average busy percentage of all CPUs with the bar label 'Avg' (might be
abbreviated to 'Av' or even just 'A'). The subsequent bars show the busy percentages of single
CPUs.
When there is not enough horizontal space to show all CPUs, only the most busy CPUs per sample will
be shown after the width of each bar has been reduced to a minimum.
By default, the categories of CPU consumption are shown by different colors in the bars, marked with
a character 'S' (system mode), 'U' (user mode), 'I' (interrupt handling), 's' (steal) and 'G'
(guest, i.e. consumed by virtual machines).
The top of the bar might consist of an unmarked color representing a 'neutral' category. Suppose
that the scale unit is 5% per line and the total busy percentage is 54% consisting of two categories
of 27%. The two categories will be rounded to 25% (5 lines of 5% each) but the total busy
percentage will be rounded to 55% (11 lines of 5%). Then the top line will represent a 'neutral'
category.
By pressing the 'H' key or by starting atop with the '-H' flag, no categories are shown.
A red line is drawn in the bar graph as critical threshold. By default this value is 90% and can be
modified by the 'cpucritperc' option in the configuration file (see separate atoprc man page). When
this value is set to zero, no threshold line will be drawn.
Memory and swap space
Memory is presented as a column in which the specific categories of memory consumption are shown.
These categories are (code, data and stack of) processes/kernel, slab caches (i.e. dynamically
allocated kernel memory), shared memory, tmpfs, static huge pages, page cache and free memory.
Swap space (if present) is also presented as a column in which the categories processes/tmpfs,
shared memory and free space are shown.
At the right side memory-related event counters are shown.
The bottom three counters are colored green when there is no memory pressure. When considerable
activity is noticed such counter might be colored orange and with high activity red.
When memory pressure starts, usually memory page scanning will be activated first. When pressure
increases, memory pages of processes might be swapped out to swap space (if present).
The 'oomkills' counter (Out Of Memory killing) is most serious: it reflects the number of processes
that are killed due to lack of memory (and swap). Therefore this counter shows the absolute number
(not per second) of processes being killed during the last interval and will immediately be colored
red when it is 1 or more. Besides, after atop has noticed OOM killing the 'oomkills' counter
remains orange for the next 15 minutes, just in case that you have missed the OOM killing event
itself.
When there is enough vertical space in the memory window, event counters are shown about the number
of memory pages being swapped in, the number of memory pages paged out to block devices and the
number of memory pages paged in from block devices.
Memory and swap space consumption will preferably be shown in a character-based window that
vertically uses the entire screen for optimal granularity. However, when there are a lot of disks
and/or network interfaces the memory and swap space consumption will be shown in a character-based
window that only uses the upper half of the screen.
Disks
For each disk the busy percentage is shown as a bar.
When there is not enough horizontal space to show all disks, only the most busy disks per sample
will be shown.
By default, categories of disk consumption are shown by different colors in the bars, marked with a
character 'R' (read) and 'W' (write).
The top of the bar might consist of an unmarked color representing a 'neutral' category. Suppose
that the scale unit is 5% per line and the total busy percentage is 54% consisting of two categories
of 27%. The two categories will be rounded to 25% (5 lines of 5% each) but the total busy
percentage will be rounded to 55% (11 lines of 5%). Then the top line will represent a 'neutral'
category.
By pressing the 'H' key or by starting atop with the '-H' flag, no categories are shown.
A red line is drawn in the bar graph as critical threshold. By default this value is 90% and can be
modified by the 'dskcritperc' option in the configuration file (see separate atoprc man page). When
this value is set to zero, no threshold line will be drawn.
Interfaces
For each non-virtual network interface a double bar graph is shown with a dedicated scale that
reflects the traffic rate. One of the bars shows the transmit rate ('TX') and the other bar the
receive rate ('RX'). The traffic scale of each network interface remains at its highest level. All
interface scales can be reset during the measurement by pressing the 'L' key.
Most often the real speed (maximum bandwidth) of network interfaces is not known, e.g. in case of
the network interfaces of virtual machines. Therefore it is not possible to show the interface
utilization as a percentage. However, when the real speed of an interface is known it will be shown
underneath the concerning bar graph.
When there is not enough horizontal space to show all network interfaces, only the most busy
interfaces per sample will be shown.
Usually the bar graphs will not be sorted on busy percentage when there is enough horizontal space.
However, after switching from text mode to bar graph mode the bar graphs might have been sorted because
this was needed for the presentation in text mode. The next interval in bar graph mode shows the bars
unsorted again unless the window width is unsufficient for all bars.
The remaining part of this manual page mainly describes the information shown in text mode. When certain
descriptions also apply to bar graph mode it will be mentioned explicitly.
TEXT MODE IN GENERAL
With every interval information is shown about the resource occupation on system level (CPU, memory,
disks and network layers) in the upper part of the screen. When a resource has been unused during the
interval, the line is suppressed unless the 'f' key is active.
In the bottom part of the screen cgroup level (key 'G') or process level information is shown (keys 'g',
'c', 's', 'm', 'd', 'n', 'v', 'u' or 'p'). By default, only cgroups are shown without assigned processes
in the cgroup itself nor in the cgroups underneath, unless the 'a' key (all) is active. By default, only
processes are shown that were active during the interval unless the 'a' key (all) is active.
The intervals are repeated till the number of samples (specified as command argument) is reached, or till
the key 'q' is pressed in interactive mode.
When atop is started, it checks whether the standard output channel is connected to a screen, or to a
file/pipe. In the first case it produces screen control codes (via the ncurses library) and behaves
interactively. In the second case it produces flat text output.
In interactive mode, the output of atop scales dynamically to the current dimensions of the
screen/window.
If the window is resized horizontally, columns will be added or removed automatically. For this purpose,
every column has a particular weight. The columns with the highest weights that fit within the current
width will be shown.
If the window is resized vertically, lines of the process/thread list will be added or removed
automatically.
In interactive mode the output of atop can be controlled by pressing particular keys. However it is also
possible to specify such key as flag on the command line. In that case atop switches to the indicated
mode on beforehand. This mode can be modified again interactively. Specifying such key as flag is
especially useful when running atop with output to a pipe or file (non-interactively). These flags are
the same as the keys that can be pressed in interactive mode (see section INTERACTIVE COMMANDS).
Additional flags are available to support storage of atop-data in raw format (see section RAW DATA
STORAGE).
The status line in the initial screen shows if atop runs with restricted view (as unprivileged user) or
unrestricted view (as privileged user). In case of restricted view atop does not have the privileges (no
root identity nor the necessary capabilities) to retrieve all counter values on system level and on
process level.
PROCESS ACCOUNTING
With every interval, atop reads the kernel administration to obtain information about all running
processes. However, it is likely that processes have terminated during the interval. These processes
might have consumed system resources during this interval before they terminated. Therefore, atop tries
to read the process accounting records that contain the accounting information of terminated processes
and report these processes too. Only when the process accounting mechanism in the kernel is activated,
the kernel writes such process accounting record to a file for every process that terminates.
There are various ways for atop to get access to the process accounting records (tried in this order):
1. When the environment variable ATOPACCT is set, it specifies the name of the process accounting file.
In that case, process accounting for this file should have been activated on beforehand. Before
opening this file for reading, atop drops its root privileges (if any).
When this environment variable is present but its contents is empty, process accounting will not be
used at all.
2. This is the preferred way of handling process accounting records!
When the atopacctd daemon is active, it has activated the process accounting mechanism in the kernel
and transfers to original accounting records to shadow files. In that case, atop drops its root
privileges and opens the current shadow file for reading.
This way is preferred, because the atopacctd daemon maintains full control of the size of the
original process accounting file written by the kernel and the shadow files read by the atop
process(es).
The atopacct service will be activated before the atop service to enable atop to detect that process
accounting is managed by the atopacctd daemon. As a forking service, atopacctd takes care that all
directories and files are initialized before the parent process dies. The child process continues as
the daemon process.
For further information, refer to the atopacctd man page.
3. When the atopacctd daemon is not active, atop verifies if the process accounting mechanism has been
switched on via the separate psacct or acct package (the package name depends on the Linux distro).
In that case, one of the files /var/log/pacct, /var/account/pacct or /var/log/account/pacct is in use
as process accounting file and atop opens this file for reading.
4. As a last possibility, atop itself tries to activate the process accounting mechanism (requires root
privileges) using the file /var/cache/atop.d/atop.acct (to be written by the kernel, to be read by
atop itself). Process accounting remains active as long as at least one atop process is alive.
Whenever the last atop process stops (either by pressing 'q' or by 'kill -15'), it deactivates the
process accounting mechanism again. Therefore you should never terminate atop by 'kill -9', because
then it has no chance to stop process accounting. As a result, the accounting file may consume a lot
of disk space after a while.
To avoid that the process accounting file consumes too much disk space, atop verifies at the end of
every sample if the size of the process accounting file exceeds 200 MiB and if this atop process is
the only one that is currently using the file. In that case the file is truncated to a size of zero.
Notice that root-privileges are required to switch on/off process accounting in the kernel. You can
start atop as a root user or specify setuid-root privileges to the executable file. In the latter
case, atop switches on process accounting and drops the root-privileges again.
If atop does not run with root-privileges, it does not show information about finished processes. It
indicates this situation with the message 'no procacct' in the top-right corner (instead of the
counter that shows the number of exited processes).
When during one interval a lot of processes have finished, atop might grow tremendously in memory when
reading all process accounting records at the end of the interval. To avoid such excessive growth atop
will never read more than 50 MiB with process information from the process accounting file per interval
(approx. 54000 finished processes). In interactive mode a warning is given whenever processes have been
skipped for this reason.
COLORS
For the resource consumption on system level, atop uses colors in text mode to indicate that a critical
occupation percentage has been (almost) reached. A critical occupation percentage means that is likely
that this load causes a noticeable negative performance influence for applications using this resource.
The critical percentage depends on the type of resource: e.g. the performance influence of a disk with a
busy percentage of 80% might be more noticeable for applications/users than a CPU with a busy percentage
of 90%.
Currently atop uses the following default values to calculate a weighted percentage per resource:
Processor
A busy percentage of 90% or higher is considered 'critical' (also in bar graph mode).
Disk
A busy percentage of 90% or higher is considered 'critical'.
Network
A busy percentage of 90% or higher for the load of an interface is considered 'critical'.
Memory
An occupation percentage of 90% is considered 'critical'. Notice that this occupation percentage is
the accumulated memory consumption of the kernel (including slab) and all processes. The memory for
the page cache ('cache' and 'buff' in the MEM-line) and the reclaimable part of the slab ('slrec')
is not implied!
If the number of pages swapped out ('swout' in the PAG-line) is larger than 10 per second, the
memory resource is considered 'critical'. A value of at least 1 per second is considered 'almost
critical'.
If the committed virtual memory exceeds the limit ('vmcom' and 'vmlim' in the SWP-line), the SWP-
line is colored due to overcommitting the system.
Swap
An occupation percentage of 80% is considered 'critical' because swap space might be completely
exhausted in the near future. It is not critical from a performance point-of-view.
These default values can be modified in the configuration file (see separate atoprc man page).
When a resource exceeds its critical occupation percentage, the concerning values in the screen line are
colored red by default.
When a resource exceeds (by default) 80% of its critical percentage (so it is almost critical), the
concerning values in the screen line are colored cyan by default. This 'almost critical percentage' (one
value for all resources) can be also modified in the configuration file (see separate atoprc man page).
The default colors red and cyan can be modified in the configuration file as well (see separate atoprc
man page).
With the key 'x' (or flag -x), the use of colors can be suppressed in text mode. The use of colors is
however mandatory in case of bar graph mode.
NETATOP OR NETATOP-BPF MODULE
Per-process and per-thread network activity can be measured by the netatop kernel module or the netatop-
bpf BPF module that can be separately installed.
When atop gathers counters for a new interval, it verifies if the netatop or netatop-bpf module is
currently active. If so, atop obtains the relevant network counters from this module and shows the number
of sent and received packets per process/thread in the generic screen. Besides, detailed counters can be
requested by pressing the 'n' key.
When the netatopd daemon is running in combination with the netatop module, atop also reads the network
counters of exited processes that are logged by this daemon (comparable with process accounting).
More information about the optional netatop kernel module and the netatopd daemon can be found in the
concerning man-pages and on the website mentioned at the end of this manual page.
GPU STATISTICS GATHERING
GPU statistics can be gathered by atopgpud which is a separate data collection daemon process. It
gathers cumulative utilization counters of every Nvidia GPU in the system, as well as utilization
counters of every process that uses a GPU. When atop notices that the daemon is active, it reads these
GPU utilization counters with every interval.
The atopgpud daemon is written in Python, so a Python interpreter should be installed on the target
system. For the gathering of the statistics, the pynvml module is used by the daemon. Be sure that this
module is installed on the target system before activating the daemon, by running the command pip as root
user:
pip install nvidia-ml-py
The atopgpud daemon is installed by default as part of the atop package, but it is not automatically
enabled. The daemon can be enabled and started now by running the following commands (as root):
systemctl enable atopgpu
systemctl start atopgpu
Find a description about the utilization counters in the section OUTPUT DESCRIPTION.
INTERACTIVE COMMANDS
When running atop interactively (no output redirection), keys can be pressed to control the output. In
general, lower case keys can be used to show other information for the active processes while certain
upper case keys can be used to influence the sort order of the active process/thread list. Some of these
keys can also be used to switch from bar graph mode to particular detailed process information in text
mode.
g Show generic output (default).
Per process the following fields are shown in case of a window-width of 80 positions: process-id,
CPU consumption during the last interval in system and user mode, the virtual and resident memory
growth of the process.
The data transfer per process for read/write on disk can only be shown when atop runs with root
privileges.
When the optional module netatop or netatop-bpf is loaded, the data transfer for send/receive of
network packets is shown for each process.
The last columns contain the state, the occupation percentage for the chosen resource (default: CPU)
and the process name.
When more than 80 positions are available, other information is added.
m Show memory related output.
Per process the following fields are shown in case of a window width of 80 positions: process-id,
minor and major memory faults, size of virtual shared text, total virtual process size, total
resident process size, virtual and resident growth during last interval, memory occupation
percentage and process name.
When more than 80 positions are available, other information is added.
For memory consumption, always all processes are shown (also the processes that were not active
during the interval).
d Show disk-related output.
When atop runs with root privileges, the following fields are shown: process-id, amount of data read
from disk, amount of data written to disk, amount of data that was written but has been withdrawn
again (WCANCL), disk occupation percentage and process name.
n Show network related output.
Per process the following fields are shown in case of a window width of 80 positions: process-id,
thread-id, total bandwidth for received packets, total bandwidth for sent packets, number of
received TCP packets with the average size per packet (in bytes), number of sent TCP packets with
the average size per packet (in bytes), number of received UDP packets with the average size per
packet (in bytes), number of sent UDP packets with the average size per packet (in bytes), the
network occupation percentage and process name.
This information can only be shown when the optional module netatop or netatop-bpf is installed.
When more than 80 positions are available, other information is added.
s Show scheduling characteristics.
Per process the following fields are shown in case of a window width of 80 positions: process-id,
number of threads in state 'running' (R), number of threads in state 'interruptible sleeping' (S),
number of threads in state 'uninterruptible sleeping' (D), number of threads in state 'idle' (I),
scheduling policy (normal timesharing, realtime round-robin, realtime fifo), nice value, priority,
realtime priority, current processor, status, exit code, state, the occupation percentage for the
chosen resource and the process name.
When more than 80 positions are available, other information is added.
v Show various process characteristics.
Per process the following fields are shown in case of a window width of 80 positions: process-id,
user name and group, start date and time, status (e.g. exit code if the process has finished),
state, the occupation percentage for the chosen resource and the process name.
When more than 80 positions are available, other information is added.
c Show the command line of the process.
Per process the following fields are shown: process-id, the occupation percentage for the chosen
resource and the command line including arguments.
G Show cgroup v2 information.
Show a hierarchical structure of cgroups and related metrics. Optionally, the processes assigned to
each cgroup can be shown. With the keys/flags '2' till '7' the level depth of the cgroups can be
chosen ('7' is default). With key/flag '8' the assigned active processes are shown as well, except
the kernel processes (usually in the root cgroup). With key/flag '9' all active processes are
shown, including the kernel processes.
With key/flag 'a' (toggle) all cgroups and all processes are shown instead of only the active
cgroups and processes. A cgroup is considered inactive when no processes are assigned to that
cgroup nor to the cgroups underneath.
With key/flag 'C' the output is sorted on CPU consumption, with key/flag 'M' sorted on memory
consumption and with key/flag 'D' sorted on disk consumption.
e Show GPU utilization.
Per process at least the following fields are shown: process-id, range of GPU numbers on which the
process currently runs, GPU busy percentage on all GPUs, memory busy percentage (i.e. read and write
accesses on memory) on all GPUs, memory occupation at the moment of the sample, average memory
occupation during the sample, and GPU percentage.
When the atopgpud daemon does not run with root privileges, the GPU busy percentage and the memory
busy percentage are not available on process level. In that case, the GPU percentage on process
level reflects the GPU memory occupation instead of the GPU busy percentage (which is preferred).
o Show the user-defined line of the process.
In the configuration file the keyword ownprocline can be specified with the description of a user-
defined output-line.
Refer to the man-page of atoprc for a detailed description.
y Show the individual threads within a process (toggle).
Single-threaded processes are still shown as one line.
For multi-threaded processes, one line represents the process while additional lines show the
activity per individual thread (in a different color). Depending on the option 'a' (all or active
toggle), all threads are shown or only the threads that were active during the last interval.
Depending on the option 'Y' (sort threads), the threads per process will be sorted on the chosen
sort criterium or not.
Whether this key is active or not can be seen in the header line.
Y Sort the threads per process when combined with option 'y' (toggle).
u Show the process activity accumulated per user.
Per user the following fields are shown: number of processes active or terminated during last
interval (or in total if combined with command 'a'), accumulated CPU consumption during last
interval in system and user mode, the current virtual and resident memory space consumed by active
processes (or all processes of the user if combined with command 'a').
When atop runs with root privileges, the accumulated read and write throughput on disk is shown.
When the optional module netatop or netatop-bpf has been installed, the accumulated number of
received and sent network packets is shown.
The last columns contain the accumulated occupation percentage for the chosen resource (default:
CPU) and the user name.
p Show the process activity accumulated per program (i.e. process name).
Per program the following fields are shown: number of processes active or terminated during last
interval (or in total if combined with command 'a'), accumulated CPU consumption during last
interval in system and user mode, the current virtual and resident memory space consumed by active
processes (or all processes of the user if combined with command 'a').
When atop runs with root privileges, the accumulated read and write throughput on disk is shown.
When the optional module netatop or netatop-bpf has been installed, the accumulated number of
received and sent network packets is shown.
The last columns contain the accumulated occupation percentage for the chosen resource (default:
CPU) and the program name.
j Show the process activity accumulated per container/pod.
Per container (e.g. Docker/Podman) or pod (e.g. Kubernetes) the following fields are shown: number
of processes active or terminated during last interval (or in total if combined with command 'a'),
accumulated CPU consumption during last interval in system and user mode, the current virtual and
resident memory space consumed by active processes (or all processes of the user if combined with
command 'a').
When atop runs with root privileges, the accumulated read and write throughput on disk is shown.
When the optional module netatop or netatop-bpf has been installed, the accumulated number of
received and sent network packets is shown.
The last columns contain the accumulated occupation percentage for the chosen resource (default:
CPU) and the container/pod name (CID/POD).
C Sort the current list in the order of CPU consumption (default). The one-but-last column changes to
'CPU'.
E Sort the current list in the order of GPU utilization (preferred, but only applicable when the
atopgpud daemon runs under root privileges) or the order of GPU memory occupation). The one-but-
last column changes to 'GPU'.
M Sort the current list in the order of resident memory consumption. The one-but-last column changes
to 'MEM'. In case of sorting on memory, the full process list will be shown (not only the active
processes).
D Sort the current list in the order of disk accesses issued. The one-but-last column changes to
'DSK'.
N Sort the current list in the order of network bandwidth (received and transmitted). The one-but-
last column changes to 'NET'.
A Sort the current list automatically in the order of the most busy system resource during this
interval. The one-but-last column shows either 'ACPU', 'AMEM', 'ADSK' or 'ANET' (the preceding 'A'
indicates automatic sorting-order). The most busy resource is determined by comparing the weighted
busy-percentages of the system resources, as described earlier in the section COLORS.
This option remains valid until another sorting-order is explicitly selected again.
A sorting order for disk is only possible when atop runs with root privileges.
A sorting order for network is only possible when the optional module netatop or netatop-bpf is
loaded.
Miscellaneous interactive commands:
? Request for help information (also the key 'h' can be pressed).
V Request for version information (version number and date).
R Gather and calculate the proportional set size of processes (toggle). Gathering of all values that
are needed to calculate the PSIZE of a process is a very time-consuming task, so this key should
only be active when analyzing the resident memory consumption of processes.
W Get the WCHAN per thread (toggle). Gathering of the WCHAN string per thread is a relatively time-
consuming task, so this key should only be made active when analyzing the reason for threads to be
in sleep state.
x Suppress colors to highlight critical resources (toggle).
Whether this key is active or not can be seen in the header line.
z The pause key can be used to freeze the current situation in order to investigate the output on the
screen. While atop is paused, the keys described above can be pressed to show other information
about the current list of processes. Whenever the pause key is pressed again, atop will continue
with a next sample.
The pause key can be used in text mode and bar graph mode.
i Modify the interval timer (default: 10 seconds). If an interval timer of 0 is entered, the interval
timer is switched off. In that case a new sample can only be triggered manually by pressing the key
't'.
The interval can be modified in text mode and bar graph mode.
t Trigger a new sample manually. This key can be pressed if the current sample should be finished
before the timer has exceeded, or if no timer is set at all (interval timer defined as 0). In the
latter case atop can be used as a stopwatch to measure the load being caused by a particular
application transaction, without knowing on beforehand how many seconds this transaction will last.
This key can be used in text mode and bar graph mode.
When viewing the contents of a raw file this key can be used to show the next sample from the file.
This key can also be used when viewing raw data via a pipe.
T When viewing the contents of a raw file this key can be used to show the previous sample from the
file, however not when reading raw data from a pipe.
This key can be used in text mode and bar graph mode.
b When viewing the contents of a raw file, this key can be used to branch to a certain timestamp
within the file either forward or backward. When viewing raw data from a pipe only forward branches
are possible.
This key can be used in text mode and bar graph mode.
r Reset all counters to zero to see the system and process activity since boot again.
This key can be used in text mode and bar graph mode.
When viewing the contents of a raw file, this key can be used to rewind to the beginning of the file
again (except when reading raw data from a pipe).
U Specify a search string for specific user names as a regular expression. From now on, only (active)
processes will be shown from a user which matches the regular expression. The system statistics are
still system wide. If the Enter-key is pressed without specifying a name, (active) processes of all
users will be shown again.
Whether this key is active or not can be seen in the header line.
I Specify a list with one or more PIDs to be selected. From now on, only processes will be shown with
a PID which matches one of the given list. The system statistics are still system wide. If the
Enter-key is pressed without specifying a PID, all (active) processes will be shown again.
Whether this key is active or not can be seen in the header line.
P Specify a search string for specific process names as a regular expression. From now on, only
processes will be shown with a name which matches the regular expression. The system statistics are
still system wide. If the Enter-key is pressed without specifying a name, all (active) processes
will be shown again.
Whether this key is active or not can be seen in the header line.
/ Specify a specific command line search string as a regular expression. From now on, only processes
will be shown with a command line which matches the regular expression. The system statistics are
still system wide. If the Enter-key is pressed without specifying a string, all (active) processes
will be shown again.
Whether this key is active or not can be seen in the header line.
J Specify a container id (e.g. Docker or Podman) or pod name (e.g. Kubernetes) of maximum 15
characters. In case the name is longer, the last 15 characters are expected. From now on, only
processes will be shown that run in that specific container or pod. The system statistics are still
system wide. If the Enter-key is pressed without specifying a container id or pod name, all
(active) processes will be shown again.
Whether this key is active or not can be seen in the header line.
Q Specify a comma-separated list of process/thread state characters. From now on, only
processes/threads will be shown that are in those specific states. Accepted states are: R
(running), S (sleeping), D (disk sleep), I (idle), T (stopped), t (tracing stop), X (dead), Z
(zombie) and P (parked). The system statistics are still system wide. If the Enter-key is pressed
without specifying a state, all (active) processes/threads will be shown again.
Whether this key is active or not can be seen in the header line.
S Specify search strings for specific logical volume names, specific disk names and specific network
interface names. All search strings are interpreted as a regular expressions. From now on, only
those system resources are shown that match the concerning regular expression. If the Enter-key is
pressed without specifying a search string, all (active) system resources of that type will be shown
again.
Whether this key is active or not can be seen in the header line.
a The 'all/active' key can be used to toggle between only showing/accumulating the processes that were
active during the last interval (default) or showing/accumulating all processes.
Whether this key is active or not can be seen in the header line.
X By default, atop shows/accumulates the processes that are alive and the processes that are exited
during the last interval. With this key (toggle), showing/accumulating the processes that are exited
can be suppressed.
Whether this key is active or not can be seen in the header line.
f Show a fixed (maximum) number of header lines for system resources (toggle). By default only the
lines are shown about system resources (CPUs, paging, logical volumes, disks, network interfaces)
that really have been active during the last interval. With this key you can force atop to show
lines of inactive resources as well.
Whether this key is active or not can be seen in the header line.
F Suppress sorting of system resources (toggle). By default system resources (CPUs, logical volumes,
disks, network interfaces) are sorted on utilization.
Whether this key is active or not can be seen in the header line.
1 Show relevant counters as an average per second (in the format '..../s') instead of as a total
during the interval (toggle).
Whether this key is active or not can be seen in the header line.
l Limit the number of system level lines for the counters per-cpu, the active disks and the network
interfaces. By default lines are shown of all CPUs, disks and network interfaces which have been
active during the last interval. Limiting these lines can be useful on systems with huge number
CPUs, disks or interfaces in order to be able to run atop on a screen/window with e.g. only 24
lines.
For all mentioned resources the maximum number of lines can be specified interactively. When using
the flag -l the maximum number of per-cpu lines is set to 0, the maximum number of disk lines to 5
and the maximum number of interface lines to 3. These values can be modified again in interactive
mode.
k Send a signal to an active process (a.k.a. kill a process).
q Quit the program.
This key can be used in text mode and bar graph mode.
PgDn Show the next page of the process/thread list.
With the arrow-down key the list can be scrolled downwards with single lines.
^F Show the next page of the process/thread list (forward).
With the arrow-down key the list can be scrolled downwards with single lines.
PgUp Show the previous page of the process/thread list.
With the arrow-up key the list can be scrolled upwards with single lines.
^B Show the previous page of the process/thread list (backward).
With the arrow-up key the list can be scrolled upwards with single lines.
^L Redraw the screen.
RAW DATA STORAGE
In order to store system and process level statistics for long-term analysis (e.g. to check the system
load and the active processes running yesterday between 3:00 and 4:00 PM), atop can store the system and
process level statistics in compressed binary format in a raw file with the flag -w followed by the
filename. If this file already exists and is recognized as a raw data file, atop will append new samples
to the file (starting with a sample which reflects the activity since boot). If the file does not exist,
it will be created.
All information about system, processes and thread activity is stored in the raw file.
The interval (default: 10 seconds) and number of samples (default: infinite) can be passed as last
arguments. Instead of the number of samples, the flag -S can be used to indicate that atop should finish
anyhow before midnight.
A raw file can be read and visualized again with the flag -r followed by the filename. If no filename is
specified, the file /var/log/atop/atop_YYYYMMDD is opened for input (where YYYYMMDD are digits
representing the current date). If a filename is specified in the format YYYYMMDD (representing any
valid date), the file /var/log/atop/atop_YYYYMMDD is opened. If a filename with the symbolic name y is
specified, yesterday's daily logfile is opened (this can be repeated so 'yyyy' indicates the logfile of
four days ago). If the filename - is used, stdin will be read.
The samples from the file can be viewed interactively by using the key 't' to show the next sample, the
key 'T' to show the previous sample, the key 'b' to branch to a particular time or the key 'r' to rewind
to the begin of the file. These keys can be used in text mode as well as in bar graph mode.
When output is redirected to a file or pipe, atop prints all samples in plain ASCII. The default line
length is 80 characters in that case. With the flag -L followed by an alternate line length, more (or
less) columns will be shown.
With the flag -b (begin time) and/or -e (end time) followed by a time argument of the form
[YYYYMMDD]hhmm[ss], a certain time period within the raw file can be selected.
Every day at midnight atop is restarted by the atop-rotate.timer and atop-rotate.service unit files, to
write compressed binary data to the file /var/log/atop/atop_YYYYMMDD with an interval of 10 minutes by
default.
Furthermore all raw files are removed that are older than 28 days (by default).
The mentioned default values can be overruled in the file /etc/default/atop that might contain other
values for LOGOPTS (by default without any flag), LOGINTERVAL (in seconds, by default 600),
LOGGENERATIONS (in days, by default 28), and LOGPATH (directory in which logfiles are stored).
Unfortunately, it is not always possible to keep the format of the raw files compatible in newer versions
of atop especially when many new counters have to be maintained. Therefore, the program atopconvert is
installed to convert a raw file created by an older version of atop to a raw file that can be read by a
newer version of atop (see the man page of atopconvert for more details).
OUTPUT DESCRIPTION
The header line always shows the host name, the end date and end time when the sample has been taken, the
current options that are active (only in text mode), and the elapsed time (duration) of the sample. The
verb 'PAUSED' will be shown behind the time when atop is currently paused with the 'z' key.
The first sample shows the system level activity since boot (the elapsed time in the header shows the
time since boot).
In text mode, atop first shows the lines related to system level activity for every sample. If a
particular system resource has not been used during the interval, the entire line related to this
resource is suppressed. So the number of system level lines may vary for each sample.
After that a list is shown of processes which have been active during the last interval. This list is
sorted on CPU consumption by default, but this order can be changed by the keys which are previously
described.
If values have to be shown by atop which do not fit in the column width, another format is used. If e.g.
a CPU consumption of 233216 milliseconds should be shown in a column width of 4 positions, it is shown as
'233s' (in seconds). For large memory figures, another unit is chosen if the value does not fit (Mb
instead of Kb, Gb instead of Mb, Tb instead of Gb, etcetera). For other values, a kind of exponent
notation is used (value 123456789 shown in a column of 5 positions gives 123e6).
OUTPUT DESCRIPTION - SYSTEM LEVEL
The system level information in text mode consists of the following output lines:
PRC Process and thread level totals.
This line contains the total CPU time consumed in system mode ('sys') and in user mode ('user'), the
total number of processes present at this moment ('#proc'), the total number of threads present at
this moment in state 'running' ('#trun'), 'sleeping interruptible' ('#tslpi'), 'sleeping
uninterruptible' ('#tslpu') and 'idle' ('#tidle'), the number of zombie processes ('#zombie'), the
number of clone system calls ('clones'), and the number of processes that ended during the interval
('#exit') when process accounting is used. Instead of '#exit' the last column may indicate that
process accounting could not be activated ('no procacct').
If the screen-width does not allow all of these counters, only a relevant subset is shown.
CPU CPU utilization.
At least one line is shown for the total occupation of all CPUs together.
In case of a multi-processor system, an additional line is shown for every individual processor
(with 'cpu' in lower case), sorted on activity. Inactive CPUs will not be shown by default. The
lines showing the per-cpu occupation contain the CPU number in the field combined with the wait
percentage.
Every line contains the percentage of CPU time spent in kernel mode by all active processes ('sys'),
the percentage of CPU time consumed in user mode ('user') for all active processes (including
processes running with a nice value larger than zero), the percentage of CPU time spent for
interrupt handling ('irq') including softirq, the percentage of unused CPU time while no processes
were waiting for disk I/O ('idle'), and the percentage of unused CPU time while at least one process
was waiting for disk I/O ('wait').
In case of per-cpu occupation, the CPU number and the wait percentage ('w') for that CPU. The
number of lines showing the per-cpu occupation can be limited.
For virtual machines, the steal-percentage ('steal') shows the percentage of CPU time stolen by
other virtual machines running on the same hardware.
For physical machines hosting one or more virtual machines, the guest percentage ('guest') shows the
percentage of CPU time used by the virtual machines. Notice that this percentage overlaps the user
percentage!
When PMC performance monitoring counters are supported by the CPU and the kernel (and atop runs with
root privileges), the number of instructions per CPU cycle ('ipc') is shown. The first sample
always shows the value 'initial', because the counters are just activated at the moment that atop is
started.
When the CPU busy percentage is high and the IPC is less than 1.0, it is likely that the CPU is
frequently waiting for memory access during instruction execution (larger CPU caches or faster
memory might be helpful to improve performance). When the CPU busy percentage is high and the IPC
is greater than 1.0, it is likely that the CPU is instruction-bound (more/faster cores might be
helpful to improve performance).
Furthermore, per CPU the effective number of cycles ('cycl') is shown. This value can reach the
current CPU frequency if such CPU is 100% busy. When an idle CPU is halted, the number of effective
cycles can be (considerably) lower than the current frequency.
Notice that the average instructions per cycle and number of cycles is shown in the CPU line for all
CPUs.
Beware that reading the cycle counter in virtual machines (guests) might introduce performance
delays. Therefore this metric is by default disabled in virtual machines. However, with the keyword
'perfevents' in the atoprc file this metric can be explicitly set to 'enable' or 'disable' (see
separate man-page of atoprc).
See also: http://www.brendangregg.com/blog/2017-05-09/cpu-utilization-is-wrong.html
In case of frequency scaling, all previously mentioned CPU percentages are relative to the used
scaling of the CPU during the interval. If a CPU has been active for e.g. 50% in user mode during
the interval while the frequency scaling of that CPU was 40%, only 20% of the full capacity of the
CPU has been used in user mode.
In case that the kernel module 'cpufreq_stats' is active (after issuing 'modprobe cpufreq_stats'),
the average frequency ('avgf') and the average scaling percentage ('avgscal') is shown. Otherwise
the current frequency ('curf') and the current scaling percentage ('curscal') is shown at the moment
that the sample is taken. Notice that average values for frequency and scaling are shown in the CPU
line for every CPU.
If the screen-width does not allow all of these counters, only a relevant subset is shown.
CPL CPU load information.
This line contains the load average figures reflecting the number of threads that are available to
run on a CPU (i.e. part of the runqueue) or that are waiting for disk I/O. These figures are
averaged over 1 ('avg1'), 5 ('avg5') and 15 ('avg15') minutes.
Furthermore the number of context switches ('csw'), the number of serviced interrupts ('intr') and
the number of available CPUs are shown.
If the screen-width does not allow all of these counters, only a relevant subset is shown.
GPU GPU utilization (Nvidia).
Read the section GPU STATISTICS GATHERING in this document to find the details about the activation
of the atopgpud daemon.
In the first column of every line, the bus-id (last nine characters) and the GPU number are shown.
The subsequent columns show the percentage of time that one or more kernels were executing on the
GPU ('gpubusy'), the percentage of time that global (device) memory was being read or written
('membusy'), the occupation percentage of memory ('memocc'), the total memory ('total'), the memory
being in use at the moment of the sample ('used'), the average memory being in use during the sample
time ('usavg'), the number of processes being active on the GPU at the moment of the sample
('#proc'), and the type of GPU.
If the screen-width does not allow all of these counters, only a relevant subset is shown.
The number of lines showing the GPUs can be limited.
MEM Memory occupation (two lines).
These lines contain the total amount of physical memory ('tot'), the amount of memory which is
currently free ('free'), the amount of memory that is available for new workloads without pushing
the system into swap ('avail'), the amount of memory in use as page cache including the total
resident shared memory ('cache'), the amount of memory within the page cache that has to be flushed
to disk ('dirty'), the amount of memory used for filesystem meta data ('buff'), the amount of memory
being used for kernel mallocs ('slab'), the amount of slab memory that is reclaimable ('slrec'), the
resident size of SYSV shared memory including tmpfs but excluding static huge pages ('shmem'), the
resident size of SYSV shared memory including static huge pages ('shrss'), the amount of SYSV shared
memory that is currently swapped ('shswp'), the amount of memory that is currently used for page
tables ('pgtab'), the number of NUMA nodes in this system ('numnode'), the amount of memory that is
currently claimed by vmware's balloon driver ('vmbal'), the amount of memory that is currently
claimed by the ARC (cache) of ZFSonlinux ('zfarc'), the amount of memory for anonymous transparent
huge pages ('anthp'), the amount of memory that is claimed for huge pages ('hptot'), the amount of
huge page memory that is really in use ('hpuse'), the amount of memory that is used for TCP sockets
('tcps'), and the amount of memory that is used for UDP sockets ('udps').
If the screen-width does not allow all of these counters, only a relevant subset is shown.
SWP Swap occupation and overcommit info.
This line contains the total amount of swap space on disk ('tot'), the amount of free swap space
('free'), the size of the swap cache ('swcac'), the size of compressed storage used for zswap
('zswap'), the real (decompressed) size of the pages stored in zswap ('zstor'), the total size of
the memory used for KSM ('ksuse', i.e. shared), and the total size of the memory saved (deduped) by
KSM ('kssav', i.e. sharing).
Furthermore the committed virtual memory space ('vmcom') and the maximum limit of the committed
space ('vmlim', which is by default swap size plus 50% of memory size) is shown. The committed
space is the reserved virtual space for all allocations of private memory space for processes. The
kernel only verifies whether the committed space exceeds the limit if strict overcommit handling is
configured (vm.overcommit_memory is 2).
LLC Last-Level Cache of CPU info.
This line contains the total memory bandwidth of LLC ('tot'), the bandwidth of the local NUMA node
('loc'), and the percentage of LLC in use ('LLCXX YY%').
Note that this feature depends on the 'resctrl' pseudo filesystem. Be sure that the kernel is built
with the relevant config and take care that the pseudo-filesystem is mounted:
mount -t resctrl resctrl -o mba_MBps /sys/fs/resctrl (on Intel)
mount -t resctrl resctrl -o cdp /sys/fs/resctrl (on AMD)
NUM Memory utilization per NUMA node (not shown for single NUMA node).
This line shows the total amount of physical memory of this node ('tot'), the amount of free memory
('free'), the amount of memory for cached file data ('file'), modified cached file data ('dirty'),
recently used memory ('activ'), less recently used memory ('inact'), memory being used for kernel
mallocs ('slab'), the amount of slab memory that is reclaimable ('slrec'), shared memory including
tmpfs ('shmem'), total huge pages ('hptot'), used huge pages('hpuse'), and the fragmentation
percentage ('frag').
NUC CPU utilization per NUMA node (not shown for single NUMA node).
This line shows the utilization percentages of all CPUs related to this NUMA node, categorized for
system mode ('sys'), user mode ('user'), user mode for niced processes ('niced'), idle mode
('idle'), wait mode ('w' preceded by the node number), irq mode ('irq'), softirq mode ('sirq'),
steal mode ('steal'), and guest mode ('guest') overlapping user mode.
PAG Paging frequency.
This line contains the number of scanned pages ('scan') due to the fact that free memory drops below
a particular threshold, the number of reclaimed pages('steal') due to the fact that free memory
drops below a particular threshold, the number times that the kernel tries to reclaim pages due to
an urgent need ('stall'),the number of process stalls to run memory compaction to allocate huge
pages ('compact'), the number of NUMA pages migrated ('numamig'), and the total number of memory
pages migrated successfully e.g. between NUMA nodes or for compaction ('migrate') are shown.
Also the number of memory pages the system read from block devices ('pgin'), the number of memory
pages the system wrote to block devices ('pgout'), the number of memory pages swapped in from zswap
('zswin'), the number of memory pages swapped out to zswap ('zswout'), the number of memory pages
the system read from swap space ('swin'), the number of memory pages the system wrote to swap space
('swout'), and the number of out-of-memory kills ('oomkill').
PSI Pressure Stall Information.
This line contains percentages about resource pressure related to CPU, memory and I/O. Certain
percentages refer to 'some' meaning that some processes/threads were delayed due to resource
overload. Other percentages refer to 'full' meaning a loss of overall throughput due to resource
overload.
The values 'cpusome', 'memsome', 'memfull', 'iosome' and 'iofull' show the pressure percentage
during the entire interval.
The values 'cs' (cpu some), 'ms' (memory some), 'mf' (memory full), 'is' (I/O some) and 'if' (I/O
full) each show three percentages separated by slashes: pressure percentage over the last 10, 60 and
300 seconds.
LVM/MDD/DSK
Logical volume/multiple device/disk utilization.
Per active unit one line is produced, sorted on unit activity. Such line shows the name (e.g.
VolGroup00-lvtmp for a logical volume or sda for a hard disk), the percentage of elapsed time during
which I/O requests were issued to the device ('busy') (note that for devices serving requests in
parallel, such as RAID arrays, SSD and NVMe, this number does not reflect their performance limits),
the number of read requests issued ('read'), the number of write requests issued ('write'), the
number of discard requests issued ('discrd') if supported by kernel version, the number of KiBytes
per read ('KiB/r'), the number of KiBytes per write ('KiB/w'), the number of KiBytes per discard
('KiB/d') if supported by kernel version, the number of MiBytes per second throughput for reads
('MBr/s'), the number of MiBytes per second throughput for writes ('MBw/s'), requests issued to the
device driver but not completed ('inflt'), the average queue depth while busy ('avq') and the
average number of milliseconds needed by a request ('avio') for seek, latency and data transfer.
If the screen-width does not allow all of these counters, only a relevant subset is shown.
The number of lines showing the units can be limited per class (LVM, MDD or DSK) with the 'l' key or
statically (see separate man-page of atoprc). By specifying the value 0 for a particular class, no
lines will be shown any more for that class.
NFM Network Filesystem (NFS) mount at the client side.
For each NFS-mounted filesystem, a line is shown that contains the mounted server directory, the
name of the server ('srv'), the total number of bytes physically read from the server ('read') and
the total number of bytes physically written to the server ('write'). Data transfer is subdivided
in the number of bytes read via normal read() system calls ('nread'), the number of bytes written
via normal read() system calls ('nwrit'), the number of bytes read via direct I/O ('dread'), the
number of bytes written via direct I/O ('dwrit'), the number of bytes read via memory mapped I/O
pages ('mread'), and the number of bytes written via memory mapped I/O pages ('mwrit').
NFC Network Filesystem (NFS) client side counters.
This line contains the number of RPC calls issues by local processes ('rpc'), the number of read RPC
calls ('read') and write RPC calls ('rpwrite') issued to the NFS server, the number of RPC calls
being retransmitted ('retxmit') and the number of authorization refreshes ('autref').
NFS Network Filesystem (NFS) server side counters.
This line contains the number of RPC calls received from NFS clients ('rpc'), the number of read RPC
calls received ('cread'), the number of write RPC calls received ('cwrit'), the number of
Megabytes/second returned to read requests by clients ('MBcr/s'), the number of Megabytes/second
passed in write requests by clients ('MBcw/s'), the number of network requests handled via TCP
('nettcp'), the number of network requests handled via UDP ('netudp'), the number of reply cache
hits ('rchits'), the number of reply cache misses ('rcmiss') and the number of uncached requests
('rcnoca'). Furthermore some error counters indicating the number of requests with a bad format
('badfmt') or a bad authorization ('badaut'), and a counter indicating the number of bad clients
('badcln').
NET Network utilization (TCP/IP).
One line is shown for activity of the transport layer (TCP and UDP), one line for the IP layer and
one line per active interface.
For the transport layer, counters are shown concerning the number of received TCP segments including
those received in error ('tcpi'), the number of transmitted TCP segments excluding those containing
only retransmitted octets ('tcpo'), the number of UDP datagrams received ('udpi'), the number of UDP
datagrams transmitted ('udpo'), the number of active TCP opens ('tcpao'), the number of passive TCP
opens ('tcppo'), the number of TCP output retransmissions ('tcprs'), the number of TCP input errors
('tcpie'), the number of TCP output resets ('tcpor'), the number of UDP no ports ('udpnp'), the
number of UDP input errors ('udpie'), and the number of TCP incorrect checksums ('csumie').
If the screen-width does not allow all of these counters, only a relevant subset is shown.
These counters are related to IPv4 and IPv6 combined.
For the IP layer, counters are shown concerning the number of IP datagrams received from interfaces,
including those received in error ('ipi'), the number of IP datagrams that local higher-layer
protocols offered for transmission ('ipo'), the number of received IP datagrams which were forwarded
to other interfaces ('ipfrw'), the number of IP datagrams which were delivered to local higher-layer
protocols ('deliv'), the number of received ICMP datagrams ('icmpi'), and the number of transmitted
ICMP datagrams ('icmpo').
If the screen-width does not allow all of these counters, only a relevant subset is shown.
These counters are related to IPv4 and IPv6 combined.
For every active network interface one line is shown, sorted on the interface activity. Such line
shows the name of the interface and its busy percentage in the first column. The busy percentage
for half duplex is determined by comparing the interface speed with the number of bits transmitted
and received per second; for full duplex the interface speed is compared with the highest of either
the transmitted or the received bits. When the interface speed can not be determined (e.g. for the
loopback interface), '---' is shown instead of the percentage.
Furthermore the number of received packets ('pcki'), the number of transmitted packets ('pcko'), the
line speed of the interface ('sp'), the effective amount of bits received per second ('si'), the
effective amount of bits transmitted per second ('so'), the number of collisions ('coll'), the
number of received multicast packets ('mlti'), the number of errors while receiving a packet
('erri'), the number of errors while transmitting a packet ('erro'), the number of received packets
dropped ('drpi'), and the number of transmitted packets dropped ('drpo').
If the screen-width does not allow all of these counters, only a relevant subset is shown.
The number of lines showing the network interfaces can be limited.
IFB Infiniband utilization.
For every active Infiniband port one line is shown, sorted on activity. Such line shows the name of
the port and its busy percentage in the first column. The busy percentage is determined by taking
the highest of either the transmitted or the received bits during the interval, multiplying that
value by the number of lanes and comparing it against the maximum port speed.
Furthermore the number of received packets divided by the number of lanes ('pcki'), the number of
transmitted packets divided by the number of lanes ('pcko'), the maximum line speed ('sp'), the
effective amount of bits received per second ('si'), the effective amount of bits transmitted per
second ('so'), and the number of lanes ('lanes').
If the screen-width does not allow all of these counters, only a relevant subset is shown.
The number of lines showing the Infiniband ports can be limited.
OUTPUT DESCRIPTION - CGROUPS LEVEL (V2)
In the bottom part of the screen a hierarchical list of cgroups can be shown. By default, cgroups without
assigned processes in the cgroup itself and the cgroups underneath will be suppressed. By pressing the
'a' key (toggle) all cgroups will be shown.
When depth level '8' or '9' has been selected (by pressing the corresponding key) the assigned processes
are shown as well. By default, only the processes that were active during the interval. By pressing the
'a' key (toggle) all processes will be shown.
Per cgroup the following fields may be shown (in alphabetical order), depending on the current width of
your window:
CGROUP Name of the cgroup (version 2), i.e. the directory name in the cgroup hierarchy. This root
cgroup '/' corresponds to the cgroup root directory, which is usually '/sys/fs/cgroup'.
CPUBUSY The consumed CPU percentage by this cgroup and all cgroups underneath (as a percentage of one
CPU). Value -1 means undefined.
CPUMAX The 'cpu.max' value of this cgroup (version 2), calculated as percentage of one CPU. Value -1
means maximum, while value -2 means undefined.
CPUPS The CPU pressure percentage ('some') in this cgroup and cgroups underneath.
CPUWGT The 'cpu.weight' value of this cgroup (version 2). Value -2 means undefined.
DISKIO The amount of data transferred to/from physical disks in this cgroup and the cgroups underneath.
Value -1 means undefined.
DSKPS The disk pressure percentage ('full') in this cgroup and cgroups underneath.
IOWGT The 'io.weight' value of this cgroup (version 2). Value -2 means undefined.
MEMMAX The 'memory.max' value of this cgroup (version 2). Value -1 means maximum, while value -2 means
undefined.
MEMORY The current memory occupation of this cgroup and all cgroups underneath. Value -1 means
undefined.
MEMPS The memory pressure percentage ('full') in this cgroup and cgroups underneath.
NPROCS The number of processes assigned to this cgroup.
PBELOW The number of processes assigned to the cgroups underneath this cgroup.
SWPMAX The 'memory.swap.max' value of this cgroup (version 2). Value -1 means maximum, while value -2
means undefined.
OUTPUT DESCRIPTION - PROCESS LEVEL
In the bottom part of the screen, a list of processes can be shown from which the resource utilization
has changed during the last interval. These processes might have used CPU time or might have issued disk
or network requests. However a process is also shown if part of it has been paged out due to lack of
memory (while the process itself was in sleep state).
Per process the following fields may be shown (in alphabetical order), depending on the current output
mode as described in the section INTERACTIVE COMMANDS and depending on the current width of your window:
AVGRSZ The average size of one read-action on disk.
AVGWSZ The average size of one write-action on disk.
BANDWI Total bandwidth for received TCP and UDP packets consumed by this process (bits-per-second).
This value can be compared with the value 'si' on interface level (used bandwidth per
interface).
This information will only be shown when the optional module netatop or netatop-bpf is loaded.
BANDWO Total bandwidth for sent TCP and UDP packets consumed by this process (bits-per-second). This
value can be compared with the value 'so' on interface level (used bandwidth per interface).
This information will only be shown when the optional module netatop or netatop-bpf is loaded.
BDELAY Aggregated block I/O delay, i.e. time waiting for disk I/O.
CID/POD Container id (e.g. Docker or Podman) or pod name (e.g. Kubernetes) referring to the
container/pod in which the process/thread is running. When a pod name is longer than 15
characters, only the last 15 characters are shown.
If a process has been started and finished during the last interval, a '?' is shown because the
container id or pod name is not part of the standard process accounting record.
This column will only be shown when atop runs with superuser privileges and when at least one
containerized process is detected.
CMD The name of the process. This name can be surrounded by "less/greater than" signs ('<name>')
which means that the process has finished during the last interval. A single accounting record
is written for the entire process on termination of the last thread in the process. When the
main thread exits, the process name is changed to the thread name.
Behind the abbreviation 'CMD' in the header line, the current page number and the total number
of pages of the process/thread list are shown.
COMMAND-LINE
The full command line of the process (including arguments). If the length of the command line
exceeds the length of the screen line, the arrow keys -> and <- can be used for horizontal
scroll.
The '-z <regex>' command line option can be used to prepend matching environment variables to
the displayed command line. POSIX Extended Regular Expression syntax are used (see regex(3)).
When a matching environment variable is too long (exceeding the buffer that should contain the
command line), it will be truncated.
Behind the verb 'COMMAND-LINE' in the header line, the current page number and the total number
of pages of the process/thread list are shown.
CPU The occupation percentage of this process related to the available capacity for this resource on
system level.
CPUNR The identification of the CPU the (main) thread is running on or has recently been running on.
CTID Container ID (OpenVZ). If a process has been started and finished during the last interval, a
'?' is shown because the container ID is not part of the standard process accounting record.
DSK The occupation percentage of this process related to the total load that is produced by all
processes (i.e. total disk accesses by all processes during the last interval).
This information is shown when per process "storage accounting" is active in the kernel.
EGID Effective group-id under which this process executes.
ENDATE Date that the process has been finished. If the process is still running, this field shows
'active'.
ENTIME Time that the process has been finished. If the process is still running, this field shows
'active'.
ENVID Virtual environment identified (OpenVZ only).
EUID Effective user-id under which this process executes.
EXC The exit code of a terminated process (second position of column 'ST' is E) or the fatal signal
number (second position of column 'ST' is S or C).
FSGID Filesystem group-id under which this process executes.
FSUID Filesystem user-id under which this process executes.
GPU When the atopgpud daemon does not run with root privileges, the GPU percentage reflects the GPU
memory occupation percentage (memory of all GPUs is 100%).
When the atopgpud daemon runs with root privileges, the GPU percentage reflects the GPU busy
percentage.
GPUBUSY Busy percentage on all GPUs (one GPU is 100%).
When the atopgpud daemon does not run with root privileges, this value is not available.
GPUNUMS Comma-separated list of GPUs used by the process during the interval. When the comma-separated
list exceeds the width of the column, a hexadecimal value is shown.
LOCKSZ The virtual amount of memory being locked (i.e. non-swappable) by this process (or user).
MAJFLT The number of page faults issued by this process that have been solved by creating/loading the
requested memory page.
MEM The occupation percentage of this process related to the available capacity for this resource on
system level.
MEMAVG Average memory occupation during the interval on all used GPUs.
MEMBUSY Busy percentage of memory on all GPUs (one GPU is 100%), i.e. the time needed for read and
write accesses on memory.
When the atopgpud daemon does not run with root privileges, this value is not available.
MEMNOW Memory occupation at the moment of the sample on all used GPUs.
MINFLT The number of page faults issued by this process that have been solved by reclaiming the
requested memory page from the free list of pages.
NET The occupation percentage of this process related to the total load that is produced by all
processes (i.e. consumed network bandwidth of all processes during the last interval).
This information will only be shown when the optional module netatop or netatop-bpf is loaded.
NICE The more or less static priority that can be given to a process on a scale from -20 (high
priority) to +19 (low priority).
NIVCSW Number of times the process/thread was context-switched involuntarily, in case that the time
slice expired.
NPROCS The number of active and terminated processes accumulated for this user or program.
NVCSW Number of times that the process/thread was context-switched voluntarily in case of a blocking
system call, e.g. to wait for an I/O operation to complete.
PID Process-id. If a process has been started and finished during the last interval, a '?' is shown
because the process-id is not part of the standard process accounting record.
POLI The policies 'norm' (normal, which is SCHED_OTHER), 'btch' (batch) and 'idle' refer to
timesharing processes. The policies 'fifo' (SCHED_FIFO) and 'rr' (round robin, which is
SCHED_RR) refer to realtime processes.
PPID Parent process-id. If a process has been started and finished during the last interval, value 0
is shown because the parent process-id is not part of the standard process accounting record.
PRI The process' priority ranges from 0 (highest priority) to 139 (lowest priority). Priority 0 to
99 are used for realtime processes (fixed priority independent of their behavior) and priority
100 to 139 for timesharing processes (variable priority depending on their recent CPU
consumption and the nice value).
PSIZE The proportional memory size of this process (or user).
Every process shares resident memory with other processes. E.g. when a particular program is
started several times, the code pages (text) are only loaded once in memory and shared by all
incarnations. Also the code of shared libraries is shared by all processes using that shared
library, as well as shared memory and memory-mapped files. For the PSIZE calculation of a
process, the resident memory of a process that is shared with other processes is divided by the
number of sharers. This means, that every process is accounted for a proportional part of that
memory. Accumulating the PSIZE values of all processes in the system gives a reliable impression
of the total resident memory consumed by all processes.
Since gathering of all values that are needed to calculate the PSIZE is a very time-consuming
task, the 'R' key (or '-R' flag) should be active. Gathering these values also requires
superuser privileges (otherwise '?K' is shown in the output).
If a process has finished during the last interval, no value is shown since the proportional
memory size is not part of the standard process accounting record.
RDDSK The read data transfer issued physically on disk (so reading from the disk cache is not
accounted for).
Unfortunately, the kernel aggregates the data transfer of a process to the data transfer of its
parent process when terminating, so you might see transfers for (parent) processes like cron,
bash or init, that are not really issued by them.
RDELAY Runqueue delay, i.e. time spent waiting on a runqueue.
RGID The real group-id under which the process executes.
RGROW The amount of resident memory that the process has grown during the last interval. A resident
growth can be caused by touching memory pages which were not physically created/loaded before
(load-on-demand). Note that a resident growth can also be negative e.g. when part of the
process is paged out due to lack of memory or when the process frees dynamically allocated
memory. For a process which started during the last interval, the resident growth reflects the
total resident size of the process at that moment.
If a process has finished during the last interval, no value is shown since resident memory
occupation is not part of the standard process accounting record.
RNET The number of TCP- and UDP packets received by this process. This information will only be
shown when the optional module netatop or netatop-bpf is installed.
If a process has finished during the last interval, no value is shown since network counters are
not part of the standard process accounting record.
RSIZE The total resident memory usage consumed by this process (or user). Notice that the RSIZE of a
process includes all resident memory used by that process, even if certain memory parts are
shared with other processes (see also the explanation of PSIZE).
If a process has finished during the last interval, no value is shown since resident memory
occupation is not part of the standard process accounting record.
RTPR Realtime priority according the POSIX standard. Value can be 0 for a timesharing process
(policy 'norm', 'btch' or 'idle') or ranges from 1 (lowest) till 99 (highest) for a realtime
process (policy 'rr' or 'fifo').
RUID The real user-id under which the process executes.
S The current state of the (main) thread: 'R' for running (currently processing or in the
runqueue), 'S' for sleeping interruptible (wait for an event to occur), 'D' for sleeping non-
interruptible, 'Z' for zombie (waiting to be synchronized with its parent process), 'T' for
stopped (suspended or traced), 'W' for swapping, and 'E' (exit) for processes which have
finished during the last interval.
SGID The saved group-id of the process.
SNET The number of TCP and UDP packets transmitted by this process. This information will only be
shown when the optional module netatop or netatop-bpf is installed.
ST The status of a process.
The first position indicates if the process has been started during the last interval (the value
N means 'new process').
The second position indicates if the process has been finished during the last interval.
The value E means 'exit' on the process' own initiative; the exit code is displayed in the
column 'EXC'.
The value S means that the process has been terminated unvoluntarily by a signal; the signal
number is displayed in the in the column 'EXC'.
The value C means that the process has been terminated unvoluntarily by a signal, producing a
core dump in its current directory; the signal number is displayed in the column 'EXC'.
STDATE The start date of the process.
STTIME The start time of the process.
SUID The saved user-id of the process.
SWAPSZ The swap space consumed by this process (or user).
SYSCPU CPU time consumption of this process in system mode (kernel mode), usually due to system call
handling.
TCPRASZ The average size of a received TCP buffer in bytes. This information will only be shown when
the optional module netatop or netatop-bpf is installed.
TCPRCV The number of TCP packets received for this process. This information will only be shown when
the optional module netatop or netatop-bpf is installed.
TCPSASZ The average size of a transmitted TCP buffer in bytes. This information will only be shown when
the optional module netatop or netatop-bpf is installed.
TCPSND The number of TCP packets transmitted for this process. This information will only be shown
when the optional module netatop or netatop-bpf is installed.
THR Total number of threads within this process. All related threads are contained in a thread
group, represented by atop as one line or as a separate line when the 'y' key (or -y flag) is
active.
On Linux 2.4 systems it is hardly possible to determine which threads (i.e. processes) are
related to the same thread group. Every thread is represented by atop as a separate line.
TID Thread-id. All threads within a process run with the same PID but with a different TID. This
value is shown for individual threads in multi-threaded processes (when using the key 'y').
TIDLE Number of threads within this process that are in the state 'idle' (I), i.e. uninterruptible
sleeping threads that do not count for the load average.
TRUN Number of threads within this process that are in the state 'running' (R).
TSLPI Number of threads within this process that are in the state 'interruptible sleeping' (S).
TSLPU Number of threads within this process that are in the state 'uninterruptible sleeping' (D).
UDPRASZ The average size of a received UDP packet in bytes. This information will only be shown when
the optional module netatop or netatop-bpf is installed.
UDPRCV The number of UDP packets received by this process. This information will only be shown when
the optional module netatop or netatop-bpf is installed.
UDPSASZ The average size of a transmitted UDP packets in bytes. This information will only be shown
when the optional module netatop or netatop-bpf is installed.
UDPSND The number of UDP packets transmitted by this process. This information will only be shown when
the optional module netatop or netatop-bpf is installed.
USRCPU CPU time consumption of this process in user mode, due to processing the own program text.
VDATA The virtual memory size of the private data used by this process (including heap and shared
library data).
VGROW The amount of virtual memory that the process has grown during the last interval. A virtual
growth can be caused by e.g. issuing a malloc() or attaching a shared memory segment. Note that
a virtual growth can also be negative by e.g. issuing a free() or detaching a shared memory
segment. For a process which started during the last interval, the virtual growth reflects the
total virtual size of the process at that moment.
If a process has finished during the last interval, no value is shown since virtual memory
occupation is not part of the standard process accounting record.
VPID Virtual process-id (within an OpenVZ container). If a process has been started and finished
during the last interval, a '?' is shown because the virtual process-id is not part of the
standard process accounting record.
VSIZE The total virtual memory usage consumed by this process (or user).
If a process has finished during the last interval, no value is shown since virtual memory
occupation is not part of the standard process accounting record.
VSLIBS The virtual memory size of the (shared) text of all shared libraries used by this process.
VSTACK The virtual memory size of the (private) stack used by this process
VSTEXT The virtual memory size of the (shared) text of the executable program.
WCHAN Wait channel of thread in sleep state, i.e. the name of the kernel function in which the thread
has been put asleep.
Since determining the name string of the kernel function is a relatively time-consuming task,
the 'W' key (or '-W' flag) should be active.
WRDSK The write data transfer issued physically on disk (so writing to the disk cache is not accounted
for). This counter is maintained for the application process that writes its data to the cache
(assuming that this data is physically transferred to disk later on). Notice that disk I/O
needed for swapping is not taken into account.
Unfortunately, the kernel aggregates the data transfer of a process to the data transfer of its
parent process when terminating, so you might see transfers for (parent) processes like cron,
bash or init, that are not really issued by them.
WCANCL The write data transfer previously accounted for this process or another process that has been
cancelled. Suppose that a process writes new data to a file and that data is removed again
before the cache buffers have been flushed to disk. Then the original process shows the written
data as WRDSK, while the process that removes/truncates the file shows the unflushed removed
data as WCANCL.
PARSABLE OUTPUT
With the flag -P followed by a list of one or more labels (comma-separated), parsable output is produced
for each sample. The labels that can be specified for system-level statistics correspond to the labels
(first verb of each line) that can be found in the interactive output: "CPU", "cpu", "CPL", "GPU", "MEM",
"SWP", "PAG", "PSI", "LVM", "MDD", "DSK", "NFM", "NFC", "NFS", "NET", "IFB", "LLC", "NUM" and "NUC".
For cgroup-level statistics the label "CGR" is available.
For process-level statistics special labels are available: "PRG" (general), "PRC" (CPU), "PRE" (GPU),
"PRM" (memory), "PRD" (disk, but requires special privileges) and "PRN" (network, only if the optional
module netatop or netatop-bpf is installed).
With the label "ALL", all system and process level statistics are shown.
The command and command line in the parsable output might contain spaces and are therefore by default
surrounded by parenthesis. However, since a space is often used as separator between the fields by
parsing tools, with the additional flag -Z it is possible to exchange the spaces in the command (line) by
underscores and omit the parenthesis.
For every interval all requested lines are shown whereafter atop shows a line just containing the label
"SEP" as a separator before the lines for the next sample are generated.
When a sample contains the values since boot, atop shows a line just containing the label "RESET" before
the lines for this sample are generated.
The first part of each output-line consists of the following six fields: label (the name of the label),
host (the name of this machine), epoch (the time of this interval as number of seconds since 1-1-1970),
date (date of this interval in format YYYY/MM/DD), time (time of this interval in format HH:MM:SS), and
interval (number of seconds elapsed for this interval).
The subsequent fields of each output-line depend on the label:
CPU Subsequent fields: total number of clock-ticks per second for this machine, number of
processors, consumption for all CPUs in system mode (clock-ticks), consumption for all CPUs in
user mode (clock-ticks), consumption for all CPUs in user mode for niced processes (clock-
ticks), consumption for all CPUs in idle mode (clock-ticks), consumption for all CPUs in wait
mode (clock-ticks), consumption for all CPUs in irq mode (clock-ticks), consumption for all CPUs
in softirq mode (clock-ticks), consumption for all CPUs in steal mode (clock-ticks), consumption
for all CPUs in guest mode (clock-ticks) overlapping user mode, frequency of all CPUs, frequency
percentage of all CPUs, instructions executed by all CPUs and cycles for all CPUs.
cpu Subsequent fields: total number of clock-ticks per second for this machine, processor-number,
consumption for this CPU in system mode (clock-ticks), consumption for this CPU in user mode
(clock-ticks), consumption for this CPU in user mode for niced processes (clock-ticks),
consumption for this CPU in idle mode (clock-ticks), consumption for this CPU in wait mode
(clock-ticks), consumption for this CPU in irq mode (clock-ticks), consumption for this CPU in
softirq mode (clock-ticks), consumption for this CPU in steal mode (clock-ticks), consumption
for this CPU in guest mode (clock-ticks) overlapping user mode, frequency of this CPU, frequency
percentage of this CPU, instructions executed by this CPU and cycles for this CPU.
CPL Subsequent fields: number of processors, load average for last minute, load average for last
five minutes, load average for last fifteen minutes, number of context-switches, and number of
device interrupts.
GPU Subsequent fields: GPU number, bus-id string, type of GPU string, GPU busy percentage during
last second (-1 if not available), memory busy percentage during last second (-1 if not
available), total memory size (KiB), used memory (KiB) at this moment, number of samples taken
during interval, cumulative GPU busy percentage during the interval (to be divided by the number
of samples for the average busy percentage, -1 if not available), cumulative memory busy
percentage during the interval (to be divided by the number of samples for the average busy
percentage, -1 if not available), and cumulative memory occupation during the interval (to be
divided by the number of samples for the average occupation).
MEM Subsequent fields: page size for this machine (in bytes), size of physical memory (pages), size
of free memory (pages), size of page cache (pages), size of buffer cache (pages), size of slab
(pages), dirty pages in cache (pages), reclaimable part of slab (pages), total size of vmware's
balloon pages (pages), total size of shared memory (pages), size of resident shared memory
(pages), size of swapped shared memory (pages), smaller huge page size (in bytes), total size of
smaller huge pages (huge pages), size of free smaller huge pages (huge pages), size of ARC
(cache) of ZFSonlinux (pages), size of sharing pages for KSM (pages), size of shared pages for
KSM (pages), size of memory used for TCP sockets (pages), size of memory used for UDP sockets
(pages), size of pagetables (pages), larger huge page size (in bytes), total size of larger huge
pages (huge pages), size of free larger huge pages (huge pages), size of available memory
(pages) for new workloads without swapping, and size of anonymous transparent huge pages
('normal' pages).
SWP Subsequent fields: page size for this machine (in bytes), size of swap (pages), size of free
swap (pages), size of swap cache (pages), size of committed space (pages), limit for committed
space (pages), size of the swap cache (pages), the real (decompressed) size of the pages stored
in zswap (pages), and the size of compressed storage used for zswap (pages).
LLC Subsequent fields: LLC id, percentage of LLC in use, total memory bandwidth of this LLC (in
bytes), and memory bandwidth on local NUMA node of this LLC (in bytes).
PAG Subsequent fields: page size for this machine (in bytes), number of page scans, number of
allocstalls, 0 (future use), number of swapins, number of swapouts, number of oomkills (-1 when
counter not present), number of process stalls to run memory compaction, number of pages
successfully migrated in total, number of NUMA pages migrated, number of pages read from block
devices, number of pages written to block devices, number of swapins from zswap, and number of
swapouts to zswap.
PSI Subsequent fields: PSI statistics present on this system (n or y), CPU some avg10, CPU some
avg60, CPU some avg300, CPU some accumulated microseconds during interval, memory some avg10,
memory some avg60, memory some avg300, memory some accumulated microseconds during interval,
memory full avg10, memory full avg60, memory full avg300, memory full accumulated microseconds
during interval, I/O some avg10, I/O some avg60, I/O some avg300, I/O some accumulated
microseconds during interval, I/O full avg10, I/O full avg60, I/O full avg300, and I/O full
accumulated microseconds during interval.
LVM/MDD/DSK
For every logical volume/multiple device/hard disk one line is shown.
Subsequent fields: name, number of milliseconds spent for I/O, number of reads issued, number of
sectors transferred for reads, number of writes issued, number of sectors transferred for write,
number of discards issued (-1 if not supported), number of sectors transferred for discards,
number of requests currently in flight (not yet completed), and the average queue depth while
the disk was busy.
NFM Subsequent fields: mounted NFS filesystem, total number of bytes read, total number of bytes
written, number of bytes read by normal system calls, number of bytes written by normal system
calls, number of bytes read by direct I/O, number of bytes written by direct I/O, number of
pages read by memory-mapped I/O, and number of pages written by memory-mapped I/O.
NFC Subsequent fields: number of transmitted RPCs, number of transmitted read RPCs, number of
transmitted write RPCs, number of RPC retransmissions, and number of authorization refreshes.
NFS Subsequent fields: number of handled RPCs, number of received read RPCs, number of received
write RPCs, number of bytes read by clients, number of bytes written by clients, number of RPCs
with bad format, number of RPCs with bad authorization, number of RPCs from bad client, total
number of handled network requests, number of handled network requests via TCP, number of
handled network requests via UDP, number of handled TCP connections, number of hits on reply
cache, number of misses on reply cache, and number of uncached requests.
NET First, one line is produced for the upper layers of the TCP/IP stack.
Subsequent fields: the verb "upper", number of packets received by TCP, number of packets
transmitted by TCP, number of packets received by UDP, number of packets transmitted by UDP,
number of packets received by IP, number of packets transmitted by IP, number of packets
delivered to higher layers by IP, number of packets forwarded by IP, number of input errors
(UDP), number of noport errors (UDP), number of active opens (TCP), number of passive opens
(TCP), number of passive opens (TCP), number of established connections at this moment (TCP),
number of retransmitted segments (TCP), number of input errors (TCP), number of output resets
(TCP), and number of checksum errors on received packets (TCP).
Next, one line is shown for every interface.
Subsequent fields: name of the interface, number of packets received by the interface, number of
bytes received by the interface, number of packets transmitted by the interface, number of bytes
transmitted by the interface, interface speed, and duplex mode (0=half, 1=full).
IFB Subsequent fields: name of the InfiniBand interface, port number, number of lanes, maximum rate
(Mbps), number of bytes received, number of bytes transmitted, number of packets received, and
number of packets transmitted.
NUM Subsequent fields: NUMA node number, page size for this machine (in bytes), the fragmentation
percentage of this node, size of physical memory (pages), size of free memory (pages), recently
(active) used memory (pages), less recently (inactive) used memory (pages), size of cached file
data (pages), dirty pages in cache (pages), slab memory being used for kernel mallocs (pages),
slab memory that is reclaimable (pages), shared memory including tmpfs (pages), total huge pages
(huge pages), and free huge pages (huge pages).
NUC Subsequent fields: NUMA node number, number of processors for this node, consumption for node
CPUs in system mode (clock-ticks), consumption for node CPUs in user mode (clock-ticks),
consumption for node CPUs in user mode for niced processes (clock-ticks), consumption for node
CPUs in idle mode (clock-ticks), consumption for node CPUs in wait mode (clock-ticks),
consumption for node CPUs in irq mode (clock-ticks), consumption for node CPUs in softirq mode
(clock-ticks), consumption for node CPUs in steal mode (clock-ticks), and consumption for node
CPUs in guest mode (clock-ticks) overlapping user mode.
CGR For every cgroup (level) one or two lines are shown. The first line shows the utilization and
configuration values of the cgroup. The optional second line shows the PIDs of the processes
assigned to this cgroup.
Subsequent fields of first line: character 'C', full path name of cgroup, number of processes
assigned to this group, number of processes assigned to the cgroups underneath, CPU usage in
user mode (microseconds), CPU usage in system mode (microseconds), CPU weight, CPU max, current
memory usage (pages), anonymous memory usage (pages), file memory usage (pages), kernel memory
usage (pages), shared memory usage (pages), memory max (pages), swap max (pages), number of
bytes read from disk, number of bytes written to disk, number of read requests from disk, number
of write requests to disk, the disk weight, cpu some pressure (microseconds), cpu total pressure
(microseconds), memory some pressure (microseconds), memory total pressure (microseconds), disk
some pressure (microseconds), and disk total pressure (microseconds).
Subsequent fields of second line (only when processes assigned to this cgroup): character 'P',
full path name of cgroup, and list of PIDs separated by spaces.
PRG For every process one line is shown.
Subsequent fields: PID (unique ID of task), name (between parenthesis or underscores for
spaces), state, real uid, real gid, TGID (group number of related tasks/threads), total number
of threads, exit code (in case of fatal signal: signal number + 256), start time (epoch), full
command line (between parenthesis or underscores for spaces), PPID, number of threads in state
'running' (R), number of threads in state 'interruptible sleeping' (S), number of threads in
state 'uninterruptible sleeping' (D), effective uid, effective gid, saved uid, saved gid,
filesystem uid, filesystem gid, elapsed time of terminated process (hertz), is_process (y/n),
OpenVZ virtual pid (VPID), OpenVZ container id (CTID), container/pod name (CID/POD), indication
if the task is newly started during this interval ('N'), cgroup v2 path name (between
parenthesis or underscores for spaces), end time (epoch or 0 if still active), and number of
threads in state 'idle' (I).
PRC For every process one line is shown.
Subsequent fields: PID, name (between parenthesis or underscores for spaces), state, total
number of clock-ticks per second for this machine, CPU-consumption in user mode (clockticks),
CPU-consumption in system mode (clockticks), nice value, priority, realtime priority, scheduling
policy, current CPU (-1 for exited process), sleep average, TGID (group number of related
tasks/threads), is_process (y/n), runqueue delay in nanoseconds for this thread or for all
threads (in case of process), wait channel of this thread (between parenthesis or underscores
for spaces), block I/O delay (clockticks), cgroup v2 'cpu.max' calculated as percentage (-3
means no cgroup v2 support, -2 means undefined and -1 means maximum), cgroup v2 most restrictive
'cpu.max' in upper directories calculated as percentage (-3 means no cgroup v2 support, -2 means
undefined and -1 means maximum), number of voluntary context switches, and number of involuntary
context switches.
PRE For every process one line is shown.
Subsequent fields: PID, name (between parenthesis or underscores for spaces), process state, GPU
state (A for active, E for exited, N for no GPU user), number of GPUs used by this process,
bitlist reflecting used GPUs, GPU busy percentage during interval, memory busy percentage during
interval, memory occupation (KiB) at this moment cumulative memory occupation (KiB) during
interval, and number of samples taken during interval.
PRM For every process one line is shown.
Subsequent fields: PID, name (between parenthesis or underscores for spaces), state, page size
for this machine (in bytes), virtual memory size (KiB), resident memory size (KiB), shared text
memory size (KiB), virtual memory growth (KiB), resident memory growth (KiB), number of minor
page faults, number of major page faults, virtual library exec size (KiB), virtual data size
(KiB), virtual stack size (KiB), swap space used (KiB), TGID (group number of related
tasks/threads), is_process (y/n), proportional set size (KiB) if in 'R' option is specified,
virtually locked memory space (KiB), cgroup v2 'memory.max' in KiB (-3 means no cgroup v2
support, -2 means undefined and -1 means maximum), cgroup v2 most restrictive 'memory.max' in
upper directories in KiB (-3 means no cgroup v2 support, -2 means undefined and -1 means
maximum), cgroup v2 'memory.swap.max' in KiB (-3 means no cgroup v2 support, -2 means undefined
and -1 means maximum), and cgroup v2 most restrictive 'memory.swap.max' in upper directories in
KiB (-3 means no cgroup v2 support, -2 means undefined and -1 means maximum).
PRD For every process one line is shown.
Subsequent fields: PID, name (between parenthesis or underscores for spaces), state, obsoleted
kernel patch installed ('n'), standard io statistics used ('y' or 'n'), number of reads on disk,
cumulative number of sectors read, number of writes on disk, cumulative number of sectors
written, cancelled number of written sectors, TGID (group number of related tasks/threads),
obsoleted value ('n'), and is_process (y/n).
PRN For every process one line is shown.
Subsequent fields: PID, name (between parenthesis or underscores for spaces), state, kernel
module netatop or netatop-bpf installed ('y' or 'n'), number of TCP-packets transmitted,
cumulative size of TCP-packets transmitted, number of TCP-packets received, cumulative size of
TCP-packets received, number of UDP-packets transmitted, cumulative size of UDP-packets
transmitted, number of UDP-packets received, cumulative size of UDP-packets transmitted, number
of raw packets transmitted (obsolete, always 0), number of raw packets received (obsolete,
always 0), TGID (group number of related tasks/threads) and is_process (y/n).
If the kernel module is not active, the network I/O counters per process are not relevant.
JSON OUTPUT
With the flag -J followed by a list of one or more labels (comma-separated), JSON output is produced for
each sample. The syntax and name of JSON labels are the same as for the parsable output.
SIGNALS
By sending the SIGUSR1 signal to atop a new sample will be forced, even if the current timer interval has
not exceeded yet. The behavior is similar to pressing the 't' key in an interactive session.
By sending the SIGUSR2 signal to atop a final sample will be forced after which atop will terminate.
EXAMPLES
Monitor the current system load in text mode with an interval of (default) 10 seconds:
atop
Monitor the current system load as bar graphs with an interval of 5 seconds:
atop -B 5
View the cgroups with the related processes (except kernel processes) with the possibility to review
previous samples during the live measurement:
atop -G8 -t
Store information about the system and process activity in binary compressed form to a file with an
interval of ten minutes during an hour:
atop -w /tmp/atop.raw 600 6
View the contents of this file interactively:
atop -r /tmp/atop.raw
View the processor and disk utilization of this file in parsable format:
atop -PCPU,DSK -r /tmp/atop.raw
View the contents of today's standard logfile interactively:
atop -r
View the contents of the standard logfile of the day before yesterday interactively:
atop -r yy
View the contents of the standard logfile of 2024, April 5 from 02:00 PM onwards interactively:
atop -r 20240405 -b 1400
Concatenate all raw log files of March 2024 and generate parsable output about the CPU utilization:
atopcat /var/log/atop/atop_202403?? | atop -r - -PCPU
Monitor the system load and write it to a file (in plain ASCII) with an interval of one minute during
half an hour with active processes sorted on memory consumption:
atop -M 60 30 > /log/atop.mem
FILES
/run/pacct_shadow.d/
Directory containing the process accounting shadow files that are used by atop when the atopacctd
daemon is active.
/var/cache/atop.d/atop.acct
File in which the kernel writes the accounting records when atop itself has activated the process
accounting mechanism.
/etc/atoprc
Configuration file containing system-wide default values. For further information about the default
values, refer to the atoprc man page).
~/.atoprc
Configuration file containing personal default values. For further information about the default
values, refer to the atoprc man page).
/etc/default/atop
Configuration file to overrule the settings of atop that runs in the background to create the daily
logfile. This file is created when atop is installed. The default settings are:
LOGOPTS=""
LOGINTERVAL=600
LOGGENERATIONS=28
/var/log/atop/atop_YYYYMMDD
Raw file, where YYYYMMDD are digits representing the current date. This name is used by atop
running in the background as default name for the output file, and by atop as default name for the
input file when using the -r flag.
All binary system and process level data in this file has been stored in compressed format.
/run/netatop.log
File that contains the netpertask structs containing the network counters of exited processes. These
structs are written by the netatopd daemon (which is related to the netatop module) and read by atop
after reading the standard process accounting records.
SEE ALSO
atopsar(1), atopconvert(1), atopcat(1), atophide(1), atoprc(5), atopacctd(8), netatop(4), netatopd(8),
atopgpud(8), logrotate(8)
https://www.atoptool.nl
AUTHOR
Gerlof Langeveld (gerlof.langeveld@atoptool.nl)
JC van Winkel
Linux July 2024 ATOP(1)