VMSTAT(8) System Administration VMSTAT(8)
vmstat - Report virtual memory statistics
vmstat [option ...] [delay [count]]
vmstat reports information about processes, memory, paging, block IO, traps, disks and cpu activity. The first report produced gives averages since the last reboot. Additional reports give information on a sampling period of length delay. The process and memory reports are instantaneous in either case.
delay The delay between updates in seconds. If no delay is specified, only one report is printed with the average values since boot. count Number of updates. In absence of count, when delay is defined, default is infinite. -a, --active Display active and inactive memory, given a 2.5.41 kernel or better. -f, --forks The -f switch displays the number of forks since boot. This includes the fork, vfork, and clone system calls, and is equivalent to the total number of tasks created. Each process is represented by one or more tasks, depending on thread usage. This display does not repeat. -m, --slabs Displays slabinfo. -n, --one-header Display the header only once rather than periodically. -s, --stats Displays a table of various event counters and memory statistics. This display does not repeat. -d, --disk Report disk statistics (2.5.70 or above required). -D, --disk-sum Report some summary statistics about disk activity. -p, --partition device Detailed statistics about partition (2.5.70 or above required). -S, --unit character Switches outputs between 1000 (k), 1024 (K), 1000000 (m), or 1048576 (M) bytes. Note this does not change the swap (si/so) or block (bi/bo) fields. -t, --timestamp Append timestamp to each line -w, --wide Wide output mode (useful for systems with higher amount of memory, where the default output mode suffers from unwanted column breakage). The output is wider than 80 characters per line. -y, --no-first Omits first report with statistics since system boot. -V, --version Display version information and exit. -h, --help Display help and exit.
Procs r: The number of runnable processes (running or waiting for run time). b: The number of processes blocked waiting for I/O to complete. Memory These are affected by the --unit option. swpd: the amount of swap memory used. free: the amount of idle memory. buff: the amount of memory used as buffers. cache: the amount of memory used as cache. inact: the amount of inactive memory. (-a option) active: the amount of active memory. (-a option) Swap These are affected by the --unit option. si: Amount of memory swapped in from disk (/s). so: Amount of memory swapped to disk (/s). IO bi: Kibibyte received from a block device (KiB/s). bo: Kibibyte sent to a block device (KiB/s). System in: The number of interrupts per second, including the clock. cs: The number of context switches per second. CPU These are percentages of total CPU time. us: Time spent running non-kernel code. (user time, including nice time) sy: Time spent running kernel code. (system time) id: Time spent idle. Prior to Linux 2.5.41, this includes IO-wait time. wa: Time spent waiting for IO. Prior to Linux 2.5.41, included in idle. st: Time stolen from a virtual machine. Prior to Linux 2.6.11, unknown. gu: Time spent running KVM guest code (guest time, including guest nice).
Reads total: Total reads completed successfully merged: grouped reads (resulting in one I/O) sectors: Sectors read successfully ms: milliseconds spent reading Writes total: Total writes completed successfully merged: grouped writes (resulting in one I/O) sectors: Sectors written successfully ms: milliseconds spent writing IO cur: I/O in progress s: seconds spent for I/O
reads: Total number of reads issued to this partition read sectors: Total read sectors for partition writes : Total number of writes issued to this partition requested writes: Total number of write requests made for partition
Slab mode shows statistics per slab, for more information about this information see slabinfo(5) cache: Cache name num: Number of currently active objects total: Total number of available objects size: Size of each object pages: Number of pages with at least one active object
vmstat requires read access to files under /proc. The -m requires read access to /proc/slabinfo which may not be available to standard users. Mount options for /proc such as subset=pid may also impact what is visible.
free(1), iostat(1), mpstat(1), ps(1), sar(1), top(1), slabinfo(5)
Please send bug reports to ⟨[email protected]⟩.
This page is part of the procps-ng (/proc filesystem utilities)
project. Information about the project can be found at
⟨https://gitlab.com/procps-ng/procps⟩. If you have a bug report
for this manual page, see
⟨https://gitlab.com/procps-ng/procps/blob/master/Documentation/bugs.md⟩.
This page was obtained from the project's upstream Git repository
⟨https://gitlab.com/procps-ng/procps.git⟩ on 2024-06-14. (At
that time, the date of the most recent commit that was found in
the repository was 2024-06-04.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
procps-ng 2023-01-18 VMSTAT(8)
Pages that refer to this page: cifsiostat(1), free(1), iostat(1), mpstat(1), pidstat(1), pmrep(1), sar(1), slabtop(1), top(1)