Re: Cpu usage 100% on slave. s_lock problem.

On 2013-09-17 08:40:23 -0500, Merlin Moncure wrote:
> > If you ever get into the situation I mistakenly referred to again, I'd
> > strongly suggest recompling postgres with -fno-omit-frame-pointer. That
> > makes hierarchical profiles actually useful which can help tremendously
> > with diagnosing issues like this...
>
> We may get an opportunity to do that. I'm curious enough about the
> THP compaction issues that Kevin mentioned to to maybe consider
> cranking buffers again. If I do that, it will be with strict
> instructions to the site operators to catch a profile before taking
> further action.

The THP issues should be very clearly diagnosable because a good part of
the time will be spent in the kernel. Lots of spinlocking there, but the
function names are easily discernible from pg's code.

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services