[Xymon] What do i see when i look at the memory check

[Jeremy Laidman]

2014-07-02 23:38 GMT+10:00 Eenkhoorn, (Klaas) <klaas.eenkhoorn at vtspn.nl>:

> What do i see when i look at the memory statistics page ?
>
> I see Physical (real), Actual and Swap, swap i know but what are the other
> two ?
>

It depends on the OS, but in many cases it's the same as Linux: "real"
means how much RAM is in use, and "actual" means how much RAM is in use by
processes and cannot be allocated to other processes.  To understand the
difference, you should know that Linux (and some other OSes) some spare RAM
is used by the kernel for disk buffers and other performance-enhancing
purposes.  If a process needs some more RAM, the kernel will give up some
of this buffer space, and so the RAM is available even though it's
technically in use.  So "real" means RAM used by processes and kernel, but
"actual" means how much is used by processes.j

You almost never have to care about "real" and it's generally going to be
close to how much physical RAM you have.  There's no point having RAM
sitting idle if the kernel can use it to make the system run faster.

J
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