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    Reference - VMSTAT
    Brett Lee
    =======================================
    
    
    Overview:
    ------------
    
    vmstat reports information about processes, memory, paging, block IO,
    traps, and cpu activity.  This information comes from:
    
           /proc/meminfo
           /proc/stat
           /proc/*/stat
    
    vmstat displays information in three modes:
    
           VM mode
           DISK mode
           DISK PARTITION mode
           SLAB mode
    
           ** Fields for each mode are listed below.  Or see the man page.
    
    
    Usage:
    -------
    
    man page:
    
           vmstat [-a] [-n] [delay [ count]]
           vmstat [-f] [-s] [-m]
           vmstat [-S unit]
           vmstat [-d]
           vmstat [-p disk partition]
           vmstat [-V]
    
    
    ~> vmstat help
    usage: vmstat [-V] [-n] [delay [count]]
                  -V prints version.
                  -n causes the headers not to be reprinted regularly.
                  -a print inactive/active page stats.
                  -d prints disk statistics
                  -D prints disk table
                  -p prints disk partition statistics
                  -s prints vm table
                  -m prints slabinfo
                  -S unit size
                  delay is the delay between updates in seconds.
                  unit size k:1000 K:1024 m:1000000 M:1048576 (default is K)
                  count is the number of updates.
    
    
    
    Details:
    ---------
    
    -a     ** Display active and inactive memory.
    
    -n     ** Display the header only once.
    
    -f     ** Display the number of tasks created since boot.
              (fork, vfork, and clone system calls)
    
    -s     ** Display a table of very useful information.
    
    -m     ** Display slab information.
    
    -d     ** Display disk statistics.  Ick.  See "-S".
    
    -S     ** Display results by k or K or m or M.  Ick.  See "-p".
              `vmstat -d -S M`
    
    -p     ** Display results for a partition.  Ick.  See "iostat".
              `vmstat -p sda1`
    
    
    
    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
    
    
    

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  • This site contains many of my notes from research into different aspects of the Linux kernel as well as some of the software provided by GNU and others. Thouugh these notes are not fully comprehensive or even completetly accurate, they are part of my on-going attempt to better understand this complex field. And, they are your to use.

    Should you wish to report any errors or suggestions, please let me know.

    Should you wish to make a donation for anything you may have learned here, please direct that donation to the ASPCA, with my sincere thanks.

    Brett Lee
    Everything Penguin

    The code for this site, which is just a few CGI scripts, may be found on GitHub (https://github.com/userbrett/cgindex).

    For both data encryption and password protection, try Personal Data Security (https://www.trustpds.com).


    "We left all that stuff out. If there's an error, we have this routine called 'panic', and when its called, the machine crashes, and you holler down the hall, 'Hey, reboot it.'"

        - Dennis Ritchie on Unix (vs Multics)


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