NAME | SYNOPSIS | DESCRIPTION | OPTIONS | FIELD DESCRIPTION FOR VM MODE | FIELD DESCRIPTION FOR DISK MODE | FIELD DESCRIPTION FOR DISK PARTITION MODE | FIELD DESCRIPTION FOR SLAB MODE | NOTES | FILES | SEE ALSO | BUGS | AUTHORS | REPORTING BUGS | COLOPHON

VMSTAT(8)                   System Administration                  VMSTAT(8)

NAME         top

       vmstat - Report virtual memory statistics

SYNOPSIS         top

       vmstat [options] [delay [count]]

DESCRIPTION         top

       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.

OPTIONS         top

       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.

       -V, --version
              Display version information and exit.

       -h, --help
              Display help and exit.

FIELD DESCRIPTION FOR VM MODE         top

   Procs
       r: The number of runnable processes (running or waiting for run time).
       b: The number of processes in uninterruptible sleep.

   Memory
       swpd: the amount of virtual 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
       si: Amount of memory swapped in from disk (/s).
       so: Amount of memory swapped to disk (/s).

   IO
       bi: Blocks received from a block device (blocks/s).
       bo: Blocks sent to a block device (blocks/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.

FIELD DESCRIPTION FOR DISK MODE         top

   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

FIELD DESCRIPTION FOR DISK PARTITION MODE         top

       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

FIELD DESCRIPTION FOR SLAB MODE         top

       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

NOTES         top

       vmstat does not require special permissions.

       These reports are intended to help identify system bottlenecks.
       Linux vmstat does not count itself as a running process.

       All linux blocks are currently 1024 bytes.  Old kernels may report
       blocks as 512 bytes, 2048 bytes, or 4096 bytes.

       Since procps 3.1.9, vmstat lets you choose units (k, K, m, M).
       Default is K (1024 bytes) in the default mode.

       vmstat uses slabinfo 1.1

FILES         top

       /proc/meminfo
       /proc/stat
       /proc/*/stat

SEE ALSO         top

       free(1), iostat(1), mpstat(1), ps(1), sar(1), top(1)

BUGS         top

       Does not tabulate the block io per device or count the number of
       system calls.

AUTHORS         top

       Written by Henry Ware ⟨al172@yfn.ysu.edu⟩.
       Fabian Frédérick ⟨ffrederick@users.sourceforge.net⟩ (diskstat, slab,
       partitions...)

REPORTING BUGS         top

       Please send bug reports to ⟨procps@freelists.org⟩

COLOPHON         top

       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 2017-05-03.  If you dis‐
       cover 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 man-pages@man7.org

procps-ng                      September 2011                      VMSTAT(8)

Pages that refer to this page: cifsiostat(1)free(1)iostat(1)mpstat(1)nfsiostat-sysstat(1)pidstat(1)pmrep(1)sar(1)slabtop(1)top(1)