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Re: Linux memory zone reclaim

From: Dave Crooke <dcrooke(at)gmail(dot)com>
To: Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org, Greg Smith <greg(at)2ndquadrant(dot)com>
Subject: Re: Linux memory zone reclaim
Date: 2012-07-18 03:51:35
Message-ID: CALi4UpjNs6d5w1XFkprmQuvmK+H9ucs9ua9A+TW_RWfJvnw0RA@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
On the larger, cellular Itanium systems with multiple motherboards (rx6600
to Superdome) Oracle has done a lot of tuning with the HP-UX kernel calls
to optimize for NUMA issues. Will be interesting to see what they bring to
Linux.
On Jul 17, 2012 9:01 PM, "Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com> wrote:

> On Tue, Jul 17, 2012 at 7:52 PM, Greg Smith <greg(at)2ndquadrant(dot)com> wrote:
> > Newer Linux systems with lots of cores have a problem I've been running
> into
> > a lot more lately I wanted to share initial notes on.  My "newer" means
> > running the 2.6.32 kernel or later, since I mostly track "enterprise"
> Linux
> > distributions like RHEL6 and Debian Squeeze.  The issue is around Linux's
> > zone_reclaim feature.  When it pops up, turning that feature off help a
> lot.
> > Details on what I understand of the problem are below, and as always
> things
> > may have changed already in even newer kernels.
>
> SNIP
>
> > Scott Marlowe has been griping about this on the mailing lists here for a
> > while now, and it's increasingly trouble for systems I've been seeing
> lately
> > too.  This is a well known problem with MySQL:
> >
> http://blog.jcole.us/2010/09/28/mysql-swap-insanity-and-the-numa-architecture/
>
> Thanks for the link, I'll read up on it.  I do have access to large
> (24 to 40 core) NUMA machines so I might try some benchmarking on them
> to see how they work.
>
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