[CentOS] Memory Usage in Top and System Monitor

Robert Nichols rnicholsNOSPAM at comcast.net
Wed Jul 20 20:28:22 UTC 2011

On 07/20/2011 02:56 PM, Michael McNulty wrote:
> Can someone help clear up some confusion in reading memory usage in Top and
> System monitor. Here is a picture of both.
> http://s1176.photobucket.com/albums/x327/ionosphere2011/ <mailto:centos at centos.org>
> Why does "System Monitor" show 1.7gb free out of 8gb. While Top shows all 8gb
> being used?
> If 1.7gb is free then it should not be using swap space so I assume "System
> Monitor" is reporting it incorrectly?

Take a look at the output from the 'free' command.  In the first line of
memory usage numbers, buffer memory and cache memory is included in the
"used" category.  For the numbers in the "+/- buffers/cache" line, buffer
and cache memory is considered "free" since it can easily be used to
satisfy memory requests.  The 'top' command shows just that first set
of numbers.  System Monitor shows the more meaningful number from the
second line.

Bob Nichols     "NOSPAM" is really part of my email address.
                 Do NOT delete it.

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