WHM - Discrepancy in memory used

rjhoward
rjhoward used Ask the Experts™
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This should be a real easy question for someone, but it has me stumped

I'm using a Linux-based VPS server with WHM and cPanel.

In WHM, under Service Status, I'm showing 65-70% memory use.  This is cutting things a bit close, and I was considering buying more memory.

However, I noticed that if I go to Show Current CPU Usage, and total up all the Mem% numbers, I consistently come up with a number that's FAR short of what Service Status is reporting (i.e., 35-40%).

This is a big discrepancy.  Which one should I believe and what accounts for the difference?

TIA for your help.
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Commented:
Both numbers are correct, they are simply telling you different things. The difference is due to the fact that there are consumers of memory other than processes, some of which can be quite substantial. In any modern operating system adding up the totals of process memory usage will rarely produce usefull results.

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Commented:
OK, that's helpful.  

Aside from processes and their associated data, what are some of the other consumers of memory?  VPS overhead maybe?  Interrupt handlers?  Device drivers?  What else?

Commented:
By far the largest will be the system cache. In some cases this could be over half of system memory.

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