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/ 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? Thanks -- Mike -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.centos.org/pipermail/centos/attachments/20110720/56b56815/attachment-0001.html>
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.
Thanks for the replies. I checked free and that makes sense to me now. The
only thing I cannot figure out is, if there is all this memory available why
would swap space start building?
I started checking all this out because the system slowed to a crawl after I
noticed swap space being used which does not make sense to me if there is
available memory.
total used free shared buffers cached
Mem: 8301448 7917100 384348 0 59984 6009248
-/+ buffers/cache: 1847868 6453580
Swap: 4128760 1225896 2902864
btw - this is Centos 5.6 box using the PAE kernel. 2.6.18-238.12.1.el5PAE
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On 07/20/2011 05:27 PM, Michael McNulty wrote:> Thanks for the replies. I checked free and that makes sense to me now. The only > thing I cannot figure out is, if there is all this memory available why would > swap space start building? > I started checking all this out because the system slowed to a crawl after I > noticed swap space being used which does not make sense to me if there is > available memory. > > total used free shared buffers cached > Mem: 8301448 7917100 384348 0 59984 6009248 > -/+ buffers/cache: 1847868 6453580 > Swap: 4128760 1225896 2902864 > > btw - this is Centos 5.6 box using the PAE kernel. 2.6.18-238.12.1.el5PAEThat indicates that at one time there were processes using a lot of memory, and 1.2GB got swapped out to satisfy that. Until something tries to access those pages they will just sit there in swap. Whatever process needs those pages will be a bit slow the next time it wakes up, but since you've got plento of available memory now those pages should then remain in physical memory. The system should not continue to run slow. If you like, you can force everything to be paged back in by running (as root) "swapoff -av", followed by "swapon -av" to re-activate your swap space. -- Bob Nichols "NOSPAM" is really part of my email address. Do NOT delete it.