From: Jim C. Nasby <jnasby@pervasive.com>
To: Mischa Sandberg <mischa@ca.sophos.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Solaris shared_buffers anomaly?
Date: Tue, 13 Jun 2006 18:17:30 -0500
Message-ID: <20060613231730.GS34196@pervasive.com> (raw)
In-Reply-To: <448F4842.4010305@ca.sophos.com>
References: <1150151282.14661.42.camel@tigger>
<20060613000441.GI8588@kenobi.snowman.net>
<20060613200810.GZ34196@pervasive.com>
<448F3A6E.6080908@ca.sophos.com>
<20060613224759.GM34196@pervasive.com>
<448F4842.4010305@ca.sophos.com>
On Tue, Jun 13, 2006 at 04:20:34PM -0700, Mischa Sandberg wrote:
> Jim C. Nasby wrote:
> >On Tue, Jun 13, 2006 at 03:21:34PM -0700, Mischa Sandberg wrote:
> >>Raised shared_buffers to 16000 (128MB).
> >>DB server dropped to a CRAWL.
> >>
> >>vmstat showed that it was swapping like crazy.
> >>Dropped shared_buffers back down again.
> >>Swapping stopped.
> >
> >What's sort_mem set to? I suspect you simply ran the machine out of
> >memory.
>
> 8192 (8MB). No issue when shared_buffers was 2000; same apps always.
So if all 50 backends were running a sort, you'd use 400MB. The box has
4G, right?
> >Also, Solaris by default will only use a portion of memory for
> >filesystem caching, which will kill PostgreSQL performance.
>
> Yep, tested /etc/system segmap_percent at 20,40,60.
> No significant difference between 20 and 60.
That's pretty disturbing... how large is your database?
--
Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
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To: pgsql-performance@postgresql.org
Cc: jnasby@pervasive.com, mischa@ca.sophos.com
Subject: Re: Solaris shared_buffers anomaly?
In-Reply-To: <20060613231730.GS34196@pervasive.com>
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