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VMSTAT(8)                Linux Administrator's Manual                VMSTAT(8)



NAME
       vmstat - Report virtual memory statistics

SYNOPSIS
       vmstat [-a] [-n] [-t] [-S unit] [delay [ count]]
       vmstat [-s] [-n] [-S unit]
       vmstat [-m] [-n] [delay [ count]]
       vmstat [-d] [-n] [delay [ count]]
       vmstat [-p disk partition] [-n] [delay [ count]]
       vmstat [-f]
       vmstat [-V]

DESCRIPTION
       vmstat  reports  information  about processes, memory, paging, block IO, traps, 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
       The -a switch displays active/inactive memory, given a 2.5.41 kernel or better.

       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 cre-
       ated. Each process is represented by one or more tasks, depending on thread  usage.
       This display does not repeat.

       The -t switch adds timestamp to the output.

       The -m switch displays slabinfo.

       The -n switch causes the header to be displayed only once rather than periodically.

       The -s switch displays a table of various event  counters  and  memory  statistics.
       This display does not repeat.

       delay  is the delay between updates in seconds.  If no delay is specified, only one
       report is printed with the average values since boot.

       count is the number of updates.  If no count is specified  and  delay  is  defined,
       count defaults to infinity.

       The -d reports disk statistics (2.5.70 or above required)

       The -w enlarges field width for big memory sizes

       The  -p  followed  by  some partition name for detailed statistics (2.5.70 or above
       required)

       The -S followed by k or K or m or M switches outputs between 1000,  1024,  1000000,
       or 1048576 bytes

       The -V switch results in displaying version information.


FIELD DESCRIPTION FOR VM MODE
   Procs
       r: The number of processes 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
       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
       totpages: Total number of allocated pages
       pslab: Number of pages per slab


NOTES
       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    FIXME

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


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


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

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



Throatwobbler Ginkgo Labs        27 July 1994                        VMSTAT(8)

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