Re: Adding more memory = hugh cpu load

From: Shaun Thomas <sthomas(at)peak6(dot)com>
To: alexandre - aldeia digital <adaldeia(at)gmail(dot)com>
Cc: undisclosed-recipients:;, <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Adding more memory = hugh cpu load
Date: 2011-10-10 20:25:54
Message-ID: 4E9354D2.8010608@peak6.com
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On 10/10/2011 12:31 PM, alexandre - aldeia digital wrote:

> <2011-10-10 14:18:48 BRT >LOG: checkpoint complete: wrote 6885 buffers
> (1.1%); 0 transaction log file(s) added, 0 removed, 1 recycled;
> write=29.862 s, sync=28.466 s, total=58.651 s

28.466s sync time?! That's horrifying. At this point, I want to say the
increase in effective_cache_size or shared_buffers triggered the planner
to change one of your plans significantly enough it's doing a ton more
disk IO and starving out your writes. Except you said you changed it
back and it's still misbehaving.

This also reminds me somewhat of an issue Greg mentioned a while back
with xlog storms in 9.0 databases. I can't recall how he usually "fixed"
these, though.

--
Shaun Thomas
OptionsHouse | 141 W. Jackson Blvd. | Suite 800 | Chicago IL, 60604
312-676-8870
sthomas(at)peak6(dot)com

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