Check manual page of mem.linux
Detailed usage of RAM, Swap, VMalloc and other memory areas on Linux
This check measures all of the available memory readings of the complex
Linux memory management, which are found in /proc/meminfo. You can
define levels on every useful value, not only on RAM and Swap. Please
note that the Linux memory management is very complex. This check takes
all this into account and also correctly handles the concept of
caching and the fact that Linux swaps out inactive parts of processes
even if there is enough RAM left.
This is not a bug, it's a feature. In fact it is the only way to do it right
(at least for Linux): What parts of a process currently reside in physical
RAM and what parts are swapped out is not related in a direct way with the
current memory usage.
Linux tends to swap out parts of processes even if RAM is available. It
does this in situations where disk buffers (are assumed to) speed up the
overall performance more than keeping rarely used parts of processes in RAM.
For example after a complete backup of your system you might experiance
that your swap usage has increased while you have more RAM free then
before. That is because Linux has taken RAM from processes in order to
increase disk buffers.
Per default there are various crit/warn levels set. Please use WATO
for viewing and adapting these levels.
One item per Linux host is being created.