[CentOS] OOM and Swappiness

Wed Sep 16 16:11:27 UTC 2015
Callum Scott <scott.callum at gmail.com>

Hi All,

I have a server that has its swappiness set to 0.  It is running a little
tight on memory and so there have been a couple of events where the
OOM_killer has been invoked and killed off MySQL, which you would expect.

Now if you have your swappiness at 0 then "A value of 0 instructs the
kernel not to initiate swap until the amount of free and file-backed pages
is less than the high water mark in a zone."[1]

So even in this event should I expect to start swapping instead of invoking
the oom_killer?

 Is the logic  Memory request -> OOM - > Can I swap? Y-> swap N-> OOM-Killer

Or as the OOM-Killer there to prevent an OOM Condition, that as the OOM
Condition is prevented by killing mysql and therefore we will never swap?

Any clarification on how this all works in this situation would be most


Kind Regads