vmstat - Report virtual memory statistics


   vmstat [options] [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


   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

   -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

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

   -h, --help
          Display help and exit.


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

   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)

   si: Amount of memory swapped in from disk (/s).
   so: Amount of memory swapped to disk (/s).

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

   in: The number of interrupts per second, including the clock.
   cs: The number of context switches per second.

   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.


   total: Total reads completed successfully
   merged: grouped reads (resulting in one I/O)
   sectors: Sectors read successfully
   ms: milliseconds spent reading

   total: Total writes completed successfully
   merged: grouped writes (resulting in one I/O)
   sectors: Sectors written successfully
   ms: milliseconds spent writing

   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


   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 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




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


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


   Written by Henry Ware al172@yfn.ysu.edu.
   Fabian Frdrick  ffrederick@users.sourceforge.net  (diskstat,  slab,


   Please send bug reports to procps@freelists.org


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