Provided by: pcp_6.3.3-1_amd64 
NAME
pcp-atop - Advanced System and Process Monitor
SYNOPSIS
Interactive Usage:
pcp [pcp options] atop [-aABcCdDfFgGHmMnNopRsuvxyY1] [-L linelen] [-Plabel[,label]... [-Z]] [interval
[samples]]
Writing and reading PCP archive folios:
pcp atop -w folio [-a] [-S] [interval [samples]]
pcp atop -r folio [-AcCdDfFgGmMnNopRsuvxy1] [-b [yy-mm-dd] hh:mm] [-e yy-mm-dd] hh:mm] [-L linelen]
[-Plabel[,label]... [-Z]] [interval [samples]]
DESCRIPTION
The program pcp-atop is an interactive monitor to view various aspects of load on a system. Every
interval seconds (default: 10 seconds) information is gathered about the resource occupation on system
level of the most critical hardware resources (from a performance point of view), i.e. CPUs, memory,
disks and network interfaces. Besides, information is gathered about the processes (or threads) that are
responsible for the utilization of the CPUs, memory and disks. Network load per process is shown only
when the optional pmdabpf(1) or pmdabcc(1) metrics have been installed and configured.
BAR GRAPH MODE
When running pcp-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, pcp-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 pcp-
atoprc(5) 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 pcp-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 pcp-atoprc(5) 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 pcp-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 pcp-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 insufficient 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
The initial screen in text mode shows if pcp-atop runs with restricted view (unprivileged user) or
unrestricted view (privileged user). In case of restricted view pcp-atop does not have the privileges
(root identity or necessary capabilities) to retrieve all counter values on system level and on process
level. does not have the privileges (no root identity nor the necessary capabilities) to retrieve all
counter values on system level and on process level.
With every interval information is shown about the resource occupation on system level (CPU, memory,
disks and network layers), followed by a list of processes which have been active during the last
interval. Notice that all processes that were unchanged during the last interval re not shown, unless
the key 'a' has been pressed or unless sorting on memory occupation is done (then inactive processes are
relevant as well). If the list of active processes does not entirely fit on the screen, only the top of
the list is shown (sorted in order of activity).
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 invoked via the pcp(1) command, the PCPIntro(1) options -A/--align, -a/--archive, -h/--host,
-O/--origin, -S/--start, -s/--samples, -T/--finish, -t/--interval, -v/--version, -z/--hostzone and
-z/--timezone become indirectly available. Additionally, the --hotproc option can be used to request the
per-process PCP metrics be used instead of the default proc metrics from pmdaproc(1).
When pcp-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 in‐
teractively; in the second case it produces flat text output.
In interactive mode, the output of pcp-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 automati‐
cally.
In interactive mode the output of pcp-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 pcp-atop switches to the in‐
dicated mode on beforehand. This mode can be modified again interactively. Specifying such key as flag
is especially useful when running pcp-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 COM‐
MANDS).
Additional flags are available to support storage of pcp-atop data in PCP archive format (see section PCP
DATA STORAGE).
COLORS
For the resource consumption on system level, pcp-atop uses colors in text mode to indicate that a criti‐
cal 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 re‐
source. 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 pcp-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 memo‐
ry resource is considered 'critical'. A value of at least 1 per second is considered 'almost criti‐
cal'.
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 ex‐
hausted 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 pcp-atoprc(5) 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 con‐
cerning values in the screen line are colored cyan by default. This 'almost critical percentage' (one
value for all resources) can be modified in the configuration file (see separate pcp-atoprc(5) man page).
The default colors red and cyan can be modified in the configuration file as well (see separate man-page
of pcp-atoprc(5)).
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 BPF MODULE
Per-process and per-thread network activity can be measured by the netatop BPF module that can be sepa‐
rately installed with pmdabpf(1). or pmdabcc(1).
When pcp-atop gathers counters for a new interval, it verifies if the eBPF module is currently active. If
so, pcp-atop obtains the relevant network counters from this module and shows the number of sent and re‐
ceived packets per process/thread in the generic screen. Besides, detailed counters can be requested by
pressing the 'n' key.
GPU STATISTICS GATHERING
GPU statistics can be gathered by pmdanvidia(1) which is a separate data collection daemon process. It
gathers cumulative utilization counters of every Nvidia GPU in the system, as well as utilization coun‐
ters of every process that uses a GPU. When pcp-atop notices that the daemon is active, it reads these
GPU utilization counters with every interval.
Find a description about the utilization counters in the section OUTPUT DESCRIPTION.
INTERACTIVE COMMANDS
When running pcp-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 pcp-atop accesses met‐
rics with root privileges.
When the optional pmdabpf(1) or pmdabcc(1) module netatop is loaded, the data transfer for send/re‐
ceive 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 resi‐
dent 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 dur‐
ing the interval).
d Show disk-related output.
When pcp-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 with‐
drawn 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 re‐
ceived 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 oc‐
cupation percentage and process name.
This information can only be shown when the optional pmdabpf(1) or pmdabcc(1) module netatop is in‐
stalled.
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 re‐
source and the command line including arguments.
X Show cgroup v2 information.
Per process the following fields are shown: process-id, the command name, and the cgroup path name
(horizontally scrollable).
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 occu‐
pation during the sample, and GPU percentage.
When the pmdanvidia 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 pcp-atoprc(5) 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 activ‐
ity per individual thread (in a different color). Depending on the option 'a' (all or active tog‐
gle), all threads are shown or only the threads that were active during the last interval. Depend‐
ing on the option 'Y' (sort threads), the threads per process will be sorted on the chosen sort cri‐
terion 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 inter‐
val (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 pcp-atop access metrics with root privileges, the accumulated read and write throughput on disk
is shown. When the optional pmdabpf(1) or pmdabcc(1) module 'netproc' has been installed, the num‐
ber of receive and send network calls are 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 in‐
terval (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 pcp-atop access metrics with root privileges, the accumulated read and write throughput on disk
is shown. When the pmdabcc(1) module 'netproc' has been installed, the number of receive and send
network calls are 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 pcp-atop access metrics with root privileges, the accumulated read and write throughput on disk
is shown. When the pmdabpf(1) or pmdabcc(1) module 'netproc' has been installed, the number of re‐
ceive and send network calls are 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 pm‐
danvidia 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 inter‐
val. The one-but-last column shows either 'ACPU', 'AMEM', 'ADSK' or 'ANET' (the preceding 'A' indi‐
cates 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 pcp-atop runs with root privileges. A sorting-order
for network is only possible when the pmdabpf(1) or pmdabcc(1) module 'netproc' has been installed.
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 on‐
ly 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 pcp-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, pcp-atop will contin‐
ue with the 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 be‐
fore the timer has exceeded, or if no timer is set at all (interval timer defined as 0). In the
latter case pcp-atop can be used as a stopwatch to measure the load being caused by a particular ap‐
plication 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 an archive folio, this key can be used to show the next sample from the
folio.
T When viewing the contents of an archive folio, this key can be used to show the previous sample from
the folio.
This key can be used in text mode and bar graph mode.
b When viewing the contents of an archive folio, this key can be used to move to a certain timestamp
within the file (either forward or backward).
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 an archive, this key can be used to rewind to the beginning of the file
again.
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 En‐
ter-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 charac‐
ters. 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 state characters. From now on, only processes will be
shown that are in those specific process states. Accepted states are: R (running), S (sleeping), D
(disk sleep), T (stopped), t (tracing stop), X (dead), Z (zombie) and P (parked). The system sta‐
tistics are still system wide. If the Enter-key is pressed without specifying a state, all (active)
processes 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.
G By default, pcp-atop shows/accumulates the processes that are alive and the processes that are exit‐
ed 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 pcp-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 dur‐
ing 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 pcp-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.
PCP 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), pcp-atop can store the system
and process level statistics in the PCP archive format, as an archive folio (see mkaf(1)).
All information about processes and threads is stored in the archive.
The interval (default: 10 seconds) and number of samples (default: infinite) can be passed as last argu‐
ments. Instead of the number of samples, the flag -S can be used to indicate that pcp-atop should finish
anyhow before midnight.
A PCP archive can be read and visualized again with the -r option. The argument is a comma-separated
list of names, each of which may be the base name of an archive or the name of a directory containing one
or more archives. If no argument is specified, the file $PCP_LOG_DIR/pmlogger/HOST/YYYYMMDD is opened
for input (where YYYYMMDD are digits representing the current date, and HOST is the hostname of the ma‐
chine being logged). If a filename is specified in the format YYYYMMDD (representing any valid date),
the file $PCP_LOG_DIR/pmlogger/HOST/YYYYMMDD is opened. If a filename with the symbolic name y is speci‐
fied, yesterday's daily logfile is opened (this can be repeated so 'yyyy' indicates the logfile of four
days ago).
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 beginning 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, pcp-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]hh‐
mm[ss], a certain time period within the archive can be selected.
OUTPUT DESCRIPTION
The first sample shows the system level activity since boot (the elapsed time in the header shows the
time since boot).
In text mode, pcp-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 re‐
source 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 by
default sorted on CPU consumption, but this order can be changed by the keys which are previously de‐
scribed.
If values have to be shown by pcp-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 uninter‐
ruptible' ('#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 ('#ex‐
it') 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 per‐
centage.
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 inter‐
rupt 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 num‐
ber 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 oth‐
er 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 pmdaper‐
fevent(1) 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 pcp-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 fre‐
quently 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.
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.
Frequency scaling statistics are only gathered for systems with maximum 8 CPUs, since gathering of
these values per CPU is very time consuming.
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 aver‐
aged 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 pmdanvidia 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 ('mem‐
busy'), 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 cur‐
rently 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 resi‐
dent size of SYSV shared memory including tmpfs but excluding static huge pages ('shmem'), the resi‐
dent 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 ta‐
bles ('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') and 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 per‐
centage ('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 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 ('com‐
pact'), 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 per‐
centages 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 dur‐
ing 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. Vol‐
Group00-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 num‐
ber 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 ('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 pcp-atoprc(5)). 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 be‐
ing 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 num‐
ber 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 proto‐
cols 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 ef‐
fective 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 ('dr‐
pi'), 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 ef‐
fective amount of bits received per second ('si'), the effective amount of bits transmitted per sec‐
ond ('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 - PROCESS LEVEL
Following the system level information, a list of processes is shown in text mode from which the resource
utilization has changed during the last interval. These processes might have used CPU time or 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 inter‐
face).
This information will only be shown when the optional pmdabpf(1) or pmdabcc(1) module 'netproc'
has been installed.
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 pmdabpf(1) or pmdabcc(1) module 'netproc'
has been installed.
BDELAY Aggregated block I/O delay, i.e. time waiting for disk I/O.
CGROUP Path name of the cgroup (version 2) to which this process belongs. This path name is relative
to the cgroup root directory, which is usually '/sys/fs/cgroup'.
CID/POD Container id (e.g. Docker or Podman) or pod name (e.g. Kubernetes) referring to the contain‐
er/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 'ac‐
tive'.
ENTIME Time that the process has been finished. If the process is still running, this field shows 'ac‐
tive'.
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 pmdanvidia daemon does not run with root privileges, the GPU percentage reflects the
GPU memory occupation percentage (memory of all GPUs is 100%).
When the pmdanvidia 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 pmdanvidia 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 pmdanvidia 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 re‐
quested 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 pmdabpf(1) or pmdabcc(1) module 'netproc'
has been installed.
NICE The more or less static priority that can be given to a process on a scale from -20 (high prior‐
ity) 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.
POLI The policies 'norm' (normal, which is SCHED_OTHER), 'btch' (batch) and 'idle' refer to timeshar‐
ing processes. The policies 'fifo' (SCHED_FIFO) and 'rr' (round robin, which is SCHED_RR) refer
to realtime processes.
PPID Parent process-id.
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 consump‐
tion 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 impres‐
sion 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 supe‐
ruser privileges (otherwise '?K' is shown in the output).
RDDSK The read data transfer issued physically on disk (so reading from the disk cache is not account‐
ed 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 memo‐
ry. For a process which started during the last interval, the resident growth reflects the to‐
tal resident size of the process at that moment.
RNET The number of TCP- and UDP packets received by this process. This information will only be
shown when the optional pmdabpf(1) or pmdabcc(1) netatop module 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).
RTPR Realtime priority according the POSIX standard. Value can be 0 for a timesharing process (poli‐
cy '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 run‐
queue), 'S' for sleeping interruptible (wait for an event to occur), 'D' for sleeping non-inter‐
ruptible, '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 pmdabpf(1) or pmdabcc(1) netatop module 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 col‐
umn 'EXC'.
The value S means that the process has been terminated involuntarily by a signal; the signal
number is displayed in the in the column 'EXC'.
The value C means that the process has been terminated involuntarily 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 pmdabpf(1) or pmdabcc(1) netproc module is enabled.
TCPRCV The number of tcp_recvmsg()/tcp_cleanup_rbuf() calls from this process. This information will
only be shown when the optional pmdabpf(1) or pmdabcc(1) netproc module is enabled.
TCPSASZ The average size of a TCP buffer requested to be transmitted in bytes. This information will
only be shown when the optional pmdabpf(1) or pmdabcc(1) netproc module is enabled.
TCPSND The number of tcp_sendmsg() calls from this process. This information will only be shown when
the optional pmdabpf(1) or pmdabcc(1) netproc module is enabled.
THR Total number of threads within this process. All related threads are contained in a thread
group, represented by pcp-atop as one line or as a separate line when the 'y' key (or -y flag)
is active.
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 buffer in bytes. This information will only be shown when
the optional pmdabpf(1) or pmdabcc(1) netproc module is enabled.
UDPRCV The number of udp_recvmsg()/skb_consume_udp() calls from this process. This information will
only be shown when the optional pmdabpf(1) or pmdabcc(1) netproc module is enabled.
UDPSASZ The average size of a UDP buffer requested to be transmitted in bytes. This information will
only be shown when the optional pmdabpf(1) or pmdabcc(1) netproc module is enabled.
UDPSND The number of udp_sendmsg() calls from this process. This information will only be shown when
the optional pmdabpf(1) or pmdabcc(1) netproc module is enabled.
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 li‐
brary 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 seg‐
ment. For a process which started during the last interval, the virtual growth reflects the to‐
tal virtual size of the process at that moment.
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 stan‐
dard process accounting record.
VSIZE The total virtual memory usage consumed by this process (or user).
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 be‐
fore 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 da‐
ta 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 process-level statistics special labels are introduced: "PRG" (general), "PRC" (CPU), "PRE" (GPU),
"PRM" (memory), "PRD" (disk, only if "storage accounting" is active) and "PRN" (only if the optional pmd‐
abpf(1) or pmdabcc(1) netproc module 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 pars‐
ing tools, with the additional flag -Z it is possible to exchange the spaces in the command (line) by un‐
derscores and omit the parenthesis.
For every interval all requested lines are shown whereafter pcp-atop shows a line just containing the la‐
bel "SEP" as a separator before the lines for the next sample are generated.
When a sample contains the values since boot, pcp-atop shows a line just containing the label "RESET" be‐
fore 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 proces‐
sors, 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 and fre‐
quency percentage of 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), consump‐
tion 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 all CPUs, frequency percent‐
age of all CPUs, instructions executed by all CPUs and cycles for all CPUs.
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 avail‐
able), 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 ('nor‐
mal' 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 alloc‐
stalls, 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 suc‐
cessfully migrated in total, number of NUMA pages migrated, number of pages read from block de‐
vices, 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 microsec‐
onds 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 trans‐
mitted 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 han‐
dled 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 trans‐
mitted 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 pas‐
sive opens (TCP), number of established connections at this moment (TCP), number of retransmit‐
ted 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), con‐
sumption 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.
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 parenthe‐
sis 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 num‐
ber 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, 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), 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 in‐
terval, 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 (Kbytes), resident memory size (Kbytes), shared
text memory size (Kbytes), virtual memory growth (Kbytes), resident memory growth (Kbytes), num‐
ber of minor page faults, number of major page faults, virtual library exec size (Kbytes), vir‐
tual data size (Kbytes), virtual stack size (Kbytes), swap space used (Kbytes), TGID (group num‐
ber of related tasks/threads), is_process (y/n), proportional set size (Kbytes) if in 'R' option
is specified and virtually locked memory space (Kbytes).
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 writ‐
ten, cancelled number of written sectors, TGID (group number of related tasks/threads), obsolet‐
ed 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, pmdabpf(1)
or pmdabcc(1) module 'netproc' loaded ('y' or 'n'), number of tcp_sendmsg() calls, cumulative
size of TCP buffers requested to be transmitted, number of tcp_recvmsg()/tcp_cleanup_rbuf()
calls, cumulative size of TCP buffers received, number of udp_sendmsg() calls, cumulative size
of UDP buffers requested to be transmitted, number of udp_recvmsg()/skb_consume_udp() calls, cu‐
mulative size of UDP buffers 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).
SIGNALS
By sending the SIGUSR1 signal to pcp-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 pcp-atop a final sample will be forced after which pcp-atop will termi‐
nate.
EXAMPLES
To monitor the current system load interactively with an interval of (default) 10 seconds:
pcp atop
To monitor the system load as bar graphs with an interval of 5 seconds:
pcp atop -B 5
Store information about the system and process activity in a PCP archive folio with an interval of ten
minutes during an hour:
pcp atop -w /tmp/pcp-atop 600 6
View the contents of this file interactively:
pcp atop -r /tmp/pcp-atop
View the processor and disk utilization of this file in parsable format:
pcp atop -PCPU,DSK -r /tmp/pcp-atop.folio
View the contents of today's standard logfile interactively:
pcp atop -r
View the contents of the standard logfile of the day before yesterday interactively:
pcp atop -r yy
View the contents of the standard logfile of 2023, June 7 from 02:00 PM onwards interactively:
pcp atop -r 20230607 -b 14:00
To 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:
pcp atop -M 60 30 > /log/pcp-atop.mem
NOTES
pcp-atop is based on the source code of the atop(1) command from https://atoptool.nl, maintained by
Gerlof Langeveld (gerlof.langeveld@atoptool.nl), and aims to be command line and output compatible with
it as much as possible.
Some features of pcp-atop (such as reporting on the Apache HTTP daemon, Infiniband, NFS client mounts,
hardware event counts, GPU statistics and per-process TCP and UDP statistics) are only activated if the
corresponding PCP metrics are available. Refer to the documentation for pmdaapache(1), pmdainfiniband(1),
pmdanfsclient(1), pmdanvidia(1), pmdaperfevent(1) pmdabcc(1) and pmdabpf(1) for further details on acti‐
vating these metrics.
The semantics of the per-process network statistics deviate slightly from the atop(1) tool: instead of
the number of TCP/UDP packets sent/received (which may be inaccurate due to TCP segmentation offload),
pcp-atop shows the number of tcp_sendmsg()/udp_sendmsg()/etc. kernel calls per process.
FILES
/etc/atoprc
Configuration file containing system-wide default values. For further information about the default
values, refer to the pcp-atoprc(5) man page).
~/.atoprc
Configuration file containing personal default values. For further information about the default
values, refer to the pcp-atoprc(5) man page).
PCP ENVIRONMENT
Environment variables with the prefix PCP_ are used to parameterize the file and directory names used by
PCP. On each installation, the file /etc/pcp.conf contains the local values for these variables. The
$PCP_CONF variable may be used to specify an alternative configuration file, as described in pcp.conf(5).
For environment variables affecting PCP tools, see pmGetOptions(3).
SEE ALSO
PCPIntro(1), pcp(1), pcp-atopsar(1), pmdaapache(1), pmdabcc(1), pmdabpf(1), pmdainfiniband(1), pmdanf‐
sclient(1), pmdanvidia(1), pmdaproc(1), mkaf(1), pmlogger(1), pmlogger_daily(1) and pcp-atoprc(5).
Performance Co-Pilot PCP PCP-ATOP(1)