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Re: heavy swapping, not sure why

From: Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>
To: Florian Weimer <fweimer(at)bfk(dot)de>
Cc: Alan Hodgson <ahodgson(at)simkin(dot)ca>, pgsql-general(at)postgresql(dot)org
Subject: Re: heavy swapping, not sure why
Date: 2011-08-30 07:39:28
Message-ID: CAOR=d=0MVf991m8+tA-skVCwJUYsQ6F+oifQETbis6joJ2YEug@mail.gmail.com (view raw or flat)
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Lists: pgsql-general
On Tue, Aug 30, 2011 at 12:54 AM, Florian Weimer <fweimer(at)bfk(dot)de> wrote:
> * Scott Marlowe:
>
>> On a machine with lots of memory, I've run into pathological behaviour
>> with both the RHEL 5 and Ubuntu 10.04 kernels where the kswapd starts
>> eating up CPU and swap io like mad, while doing essentially nothing.
>> Setting swappiness to 0 delayed this behaviour but did not stop it.
>> Given that I'm on a machine with 128G ram, I just put "/sbin/swapoff
>> -a" in /etc/rc.local and viola, problem solved.
>
> Was this NUMA machine?  Some older kernels can only migrate pages
> between nodes through swap.

48 core AMD Magny Cours.  I also had to turn off  zone reclaim mode on
it or it would slow to a crawl as the OS started to cache more and
more data.

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Subject: Re: heavy swapping, not sure why
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