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Full Discussion: vmstat
Top Forums Shell Programming and Scripting vmstat Post 302338535 by methyl on Tuesday 28th of July 2009 07:53:11 AM
Old 07-28-2009
Beware that the first line of statistics from vmstat are garbage.
Therefor anchal_khare post will not produce valid results.

Also beware that "vmstat 5" will not stop until it is interrupted or killed.
To get meaningful statistics from vmstat it must be run with at least two iterations:
Code:
vmstat 5 2

Then take the statistics from the last line output.
A 5-second snapshot of a unix system would be biased by vmstat itself.

In practice you get a more meaningful statistics from say:
Code:
vmstat 30 2

run every 20 mins.
 

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FREE(1) 							   User Commands							   FREE(1)

NAME
free - Display amount of free and used memory in the system SYNOPSIS
free [options] DESCRIPTION
free displays the total amount of free and used physical and swap memory in the system, as well as the buffers and caches used by the ker- nel. The information is gathered by parsing /proc/meminfo. The displayed columns are: total Total installed memory (MemTotal and SwapTotal in /proc/meminfo) used Used memory (calculated as total - free) free Unused memory (MemFree and SwapFree in /proc/meminfo) shared Memory used (mostly) by tmpfs (Shmem in /proc/meminfo, available on kernels 2.6.32, displayed as zero if not available) buffers Memory used by kernel buffers (Buffers in /proc/meminfo) cached Memory used by the page cache (calculated as Cached - Shmem in /proc/meminfo - the Cached value is actually the sum of page cache and tmpfs memory) OPTIONS
-b, --bytes Display the amount of memory in bytes. -k, --kilo Display the amount of memory in kilobytes. This is the default. -m, --mega Display the amount of memory in megabytes. -g, --giga Display the amount of memory in gigabytes. --tera Display the amount of memory in terabytes. -h, --human Show all output fields automatically scaled to shortest three digit unit and display the units of print out. Following units are used. B = bytes K = kilos M = megas G = gigas T = teras If unit is missing, and you have petabyte of RAM or swap, the number is in terabytes and columns might not be aligned with header. -c, --count count Display the result count times. Requires the -s option. -l, --lohi Show detailed low and high memory statistics. -o, --old Display the output in old format, the only difference being this option will disable the display of the "buffer adjusted" line. -s, --seconds seconds Continuously display the result delay seconds apart. You may actually specify any floating point number for delay, usleep(3) is used for microsecond resolution delay times. --si Use power of 1000 not 1024. -t, --total Display a line showing the column totals. --help Print help. -V, --version Display version information. FILES
/proc/meminfo memory information SEE ALSO
ps(1), slabtop(1), top(1), vmstat(8). AUTHORS
Written by Brian Edmonds. REPORTING BUGS
Please send bug reports to <procps@freelists.org> procps-ng September 2011 FREE(1)
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