iotop(8) [centos man page]
IOTOP(8) System Manager's Manual IOTOP(8) NAME
iotop - simple top-like I/O monitor SYNOPSIS
iotop [OPTIONS] DESCRIPTION
iotop watches I/O usage information output by the Linux kernel (requires 2.6.20 or later) and displays a table of current I/O usage by pro- cesses or threads on the system. At least the CONFIG_TASK_DELAY_ACCT, CONFIG_TASK_IO_ACCOUNTING, CONFIG_TASKSTATS and CONFIG_VM_EVENT_COUN- TERS options need to be enabled in your Linux kernel build configuration. iotop displays columns for the I/O bandwidth read and written by each process/thread during the sampling period. It also displays the per- centage of time the thread/process spent while swapping in and while waiting on I/O. For each process, its I/O priority (class/level) is shown. In addition, the total I/O bandwidth read and written during the sampling period is displayed at the top of the interface. Total DISK READ and Total DISK WRITE values represent total read and write bandwidth between processes and kernel threads on the one side and kernel block device subsystem on the other. While Actual DISK READ and Actual DISK WRITE values represent corresponding bandwidths for actual disk I/O between kernel block device subsystem and underlying hardware (HDD, SSD, etc.). Thus Total and Actual values may not be equal at any given moment of time due to data caching and I/O operations reordering that take place inside Linux kernel. Use the left and right arrows to change the sorting, r to reverse the sorting order, o to toggle the --only option, p to toggle the --pro- cesses option, a to toggle the --accumulated option, q to quit or i to change the priority of a thread or a process' thread(s). Any other key will force a refresh. OPTIONS
--version Show the version number and exit -h, --help Show usage information and exit -o, --only Only show processes or threads actually doing I/O, instead of showing all processes or threads. This can be dynamically toggled by pressing o. -b, --batch Turn on non-interactive mode. Useful for logging I/O usage over time. -n NUM, --iter=NUM Set the number of iterations before quitting (never quit by default). This is most useful in non-interactive mode. -d SEC, --delay=SEC Set the delay between iterations in seconds (1 second by default). Accepts non-integer values such as 1.1 seconds. -p PID, --pid=PID A list of processes/threads to monitor (all by default). -u USER, --user=USER A list of users to monitor (all by default) -P, --processes Only show processes. Normally iotop shows all threads. -a, --accumulated Show accumulated I/O instead of bandwidth. In this mode, iotop shows the amount of I/O processes have done since iotop started. -k, --kilobytes Use kilobytes instead of a human friendly unit. This mode is useful when scripting the batch mode of iotop. Instead of choosing the most appropriate unit iotop will display all sizes in kilobytes. -t, --time Add a timestamp on each line (implies --batch). Each line will be prefixed by the current time. -q, --quiet suppress some lines of header (implies --batch). This option can be specified up to three times to remove header lines. -q column names are only printed on the first iteration, -qq column names are never printed, -qqq the I/O summary is never printed. SEE ALSO
ionice(1), top(1), vmstat(1), atop(1), htop(1) AUTHOR
iotop was written by Guillaume Chazarain. This manual page was started by Paul Wise for the Debian project and is placed in the public domain. April 2009 IOTOP(8)
Check Out this Related Man Page
SYSTEMD-CGTOP(1) systemd-cgtop SYSTEMD-CGTOP(1) NAME
systemd-cgtop - Show top control groups by their resource usage SYNOPSIS
systemd-cgtop [OPTIONS...] [GROUP] DESCRIPTION
systemd-cgtop shows the top control groups of the local Linux control group hierarchy, ordered by their CPU, memory, or disk I/O load. The display is refreshed in regular intervals (by default every 1s), similar in style to top(1). If a control group path is specified, shows only the services of the specified control group. If systemd-cgtop is not connected to a tty, no column headers are printed and the default is to only run one iteration. The --iterations= argument, if given, is honored. This mode is suitable for scripting. Resource usage is only accounted for control groups in the relevant hierarchy, i.e. CPU usage is only accounted for control groups in the "cpuacct" hierarchy, memory usage only for those in "memory" and disk I/O usage for those in "blkio". If resource monitoring for these resources is required, it is recommended to add the CPUAccounting=1, MemoryAccounting=1 and BlockIOAccounting=1 settings in the unit files in question. See systemd.resource-control(5) for details. The CPU load value can be between 0 and 100 times the number of processors the system has. For example, if the system has 8 processors, the CPU load value is going to be between 0% and 800%. The number of processors can be found in "/proc/cpuinfo". To emphasize this: unless "CPUAccounting=1", "MemoryAccounting=1" and "BlockIOAccounting=1" are enabled for the services in question, no resource accounting will be available for system services and the data shown by systemd-cgtop will be incomplete. OPTIONS
The following options are understood: -p, --order=path Order by control group path name. -t, --order=tasks Order by number of tasks/processes in the control group. -c, --order=cpu Order by CPU load. -m, --order=memory Order by memory usage. -i, --order=io Order by disk I/O load. -b, --batch Run in "batch" mode: do not accept input and run until the iteration limit set with --iterations= is exhausted or until killed. This mode could be useful for sending output from systemd-cgtop to other programs or to a file. -r, --raw Format byte counts (as in memory usage and I/O metrics) with raw numeric values rather than human-readable numbers. --cpu=percentage, --cpu=time Controls whether the CPU usage is shown as percentage or time. By default, the CPU usage is shown as percentage. This setting may also be toggled at runtime by pressing the % key. -P Count only userspace processes instead of all tasks. By default, all tasks are counted: each kernel thread and each userspace thread individually. With this setting, kernel threads are excluded from the counting and each userspace process only counts as one, regardless how many threads it consists of. This setting may also be toggled at runtime by pressing the P key. This option may not be combined with -k. -k Count only userspace processes and kernel threads instead of all tasks. By default, all tasks are counted: each kernel thread and each userspace thread individually. With this setting, kernel threads are included in the counting and each userspace process only counts as on one, regardless how many threads it consists of. This setting may also be toggled at runtime by pressing the k key. This option may not be combined with -P. --recursive= Controls whether the number of processes shown for a control group shall include all processes that are contained in any of the child control groups as well. Takes a boolean argument, which defaults to "yes". If enabled, the processes in child control groups are included, if disabled, only the processes in the control group itself are counted. This setting may also be toggled at runtime by pressing the r key. Note that this setting only applies to process counting, i.e. when the -P or -k options are used. It has not effect if all tasks are counted, in which case the counting is always recursive. -n, --iterations= Perform only this many iterations. A value of 0 indicates that the program should run indefinitely. -d, --delay= Specify refresh delay in seconds (or if one of "ms", "us", "min" is specified as unit in this time unit). This setting may also be increased and decreased at runtime by pressing the + and - keys. --depth= Maximum control group tree traversal depth. Specifies how deep systemd-cgtop shall traverse the control group hierarchies. If 0 is specified, only the root group is monitored. For 1, only the first level of control groups is monitored, and so on. Defaults to 3. -M MACHINE, --machine=MACHINE Limit control groups shown to the part corresponding to the container MACHINE. This option may not be used when a control group path is specified. -h, --help Print a short help text and exit. --version Print a short version string and exit. KEYS
systemd-cgtop is an interactive tool and may be controlled via user input using the following keys: h Shows a short help text. Space Immediately refresh output. q Terminate the program. p, t, c, m, i Sort the control groups by path, number of tasks, CPU load, memory usage, or I/O load, respectively. This setting may also be controlled using the --order= command line switch. % Toggle between showing CPU time as time or percentage. This setting may also be controlled using the --cpu= command line switch. +, - Increase or decrease refresh delay, respectively. This setting may also be controlled using the --delay= command line switch. P Toggle between counting all tasks, or only userspace processes. This setting may also be controlled using the -P command line switch (see above). k Toggle between counting all tasks, or only userspace processes and kernel threads. This setting may also be controlled using the -k command line switch (see above). r Toggle between recursively including or excluding processes in child control groups in control group process counts. This setting may also be controlled using the --recursive= command line switch. This key is not available if all tasks are counted, it is only available if processes are counted, as enabled with the P or k keys. EXIT STATUS
On success, 0 is returned, a non-zero failure code otherwise. SEE ALSO
systemd(1), systemctl(1), systemd-cgls(1), systemd.resource-control(5), top(1) systemd 237 SYSTEMD-CGTOP(1)