VMSTAT(8)                 (2020-06-04)                  VMSTAT(8)

     NAME
          vmstat - Report virtual memory statistics

     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.  Additional 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 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).

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          -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 block (bi/bo) fields, which are always measured in
               blocks.

          -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

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

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          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
          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
          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
          vmstat does not require special permissions.

          These reports are intended to help identify system bottle-
          necks.  Linux vmstat does not count itself as a running pro-
          cess.

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          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 num-
          ber of system calls.

     AUTHORS
          Written by Henry Ware
          Fabian Fr'ed'erick (diskstat, slab, partitions...)

     REPORTING BUGS
          Please send bug reports to

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