[CentOS] OOM and Swappiness

Wed Sep 16 17:36:49 UTC 2015
m.roth at 5-cent.us <m.roth at 5-cent.us>

Gordon Messmer wrote:
> On 09/16/2015 09:11 AM, Callum Scott wrote:
>> 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.
> One thing that should be noted is that regardless of swappiness,
> overcommit might be an issue.  If a single process is using most of the
> memory in a system, and attempts to fork(), as it will if it calls
> system(), then the system may require that there is enough memory for a
> second instance of that huge process.
> This is one of the reasons why swap should be as large or larger than
> system RAM.
Excerpt on heavy-duty servers. We're certainly not going to allocate
hundreds of gigs, or a terabyte or so, for swap. (Yes, we do have servers
with that kind of RAM, and that's not counting the small SGI