[RndTbl] mysql crash and non-restart due to RAM?

[Hartmut W Sager]

It sounds like it was doing just a partial RAM defrag.  Otherwise, there
should be a single large contig (hopefully > 4GB) right after the defrag.

Hartmut W Sager - Tel +1-204-339-8331, +1-204-515-1701, +1-204-515-1700,
+1-810-471-4600, +1-909-361-6005


On 4 January 2016 at 12:54, Trevor Cordes <trevor at tecnopolis.ca> wrote:

> On 2016-01-04 Hartmut W Sager wrote:
> > I am surprised.  Doesn't a current high-grade OS like Linux (maybe not
> > Windows) routinely close the gaps in RAM by relocating running code
> > and data?  This is quite efficiently do-able in CPU architectures
>
> I just read an article about this.  Supposedly modern linux (not sure
> about RHEL6) does mem "defrag" only on oom condition (going from vague
> memory).  Discussions always crop up about having a kthread that can do
> periodic defrag outside of oom condition but I don't think this is
> being done at present.
>
> Defrag on oom does sound like what I just saw today, because when the
> oom happened there was almost no contig ram left, but when I checked
> the server a while later there were lots of bigger contigs, but still
> not enough for a 4G alloc.
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