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vmstat


SYNOPSIS

       vmstat [options] [delay [count]]


DESCRIPTION

       vmstat  reports  information about processes, memory, paging, block IO,
       traps, disks and cpu activity.

       The first report produced gives averages since the last reboot.   Addi-
       tional  reports  give information on a sampling period of length delay.
       The process and memory reports are instantaneous in either case.


OPTIONS

       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 equiva-
              lent to the total number of tasks created.  Each process is rep-
              resented 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 statis-
              tics.  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.


FIELD DESCRIPTION FOR VM MODE

   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

   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


       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

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


SEE ALSO

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


BUGS

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


AUTHORS

       Written by Henry Ware <al172@yfn.ysu.edu>.
       Fabian Frederick  <ffrederick@users.sourceforge.net>  (diskstat,  slab,
       partitions...)


REPORTING BUGS

       Please send bug reports to <procps@freelists.org>


procps-ng September 2011 VMSTAT(8)



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