From: Gavin Hamill <gdh@laterooms.com>
To: pgsql-performance@postgresql.org
Subject: Re: pg 8.1.3, AIX, huge box, painfully slow.
Date: Fri, 7 Apr 2006 23:27:59 +0100
Message-ID: <20060407232759.45581362.gdh@laterooms.com> (raw)
In-Reply-To: <17055.1144447009@sss.pgh.pa.us>
References: <20060407185823.abe93017.gdh@laterooms.com>
<1144436060.32269.13.camel@state.g2switchworks.com>
<20060407205919.a091da26.gdh@laterooms.com>
<15772.1144440362@sss.pgh.pa.us>
<20060407223635.9c4a0b38.gdh@laterooms.com>
<17055.1144447009@sss.pgh.pa.us>
On Fri, 07 Apr 2006 17:56:49 -0400
Tom Lane <tgl@sss.pgh.pa.us> wrote:
> This is not good. Did the semop storms coincide with visible
> slowdown? (I'd assume so, but you didn't actually say...)
If I'd been able to tell, then I'd tell you =) I'll have another go...
Yes, there's a definate correlation here.. I attached truss to the
main postmaster..
$ truss -Ff -p 340344 2>&1 | grep semop
here's a snippet
278774: __semop(15728650, 0x0FFFFFFFFFFF7E80, 1) = 0
155712: __semop(15728650, 0x0FFFFFFFFFFF5920, 1) = 0
278774: __semop(15728649, 0x0FFFFFFFFFFF6F10, 1)
114914: __semop(15728649, 0x0FFFFFFFFFFF6A40, 1) = 0 = 0
114914: __semop(15728650, 0x0FFFFFFFFFFF61E0, 1)
155712: __semop(15728650, 0x0FFFFFFFFFFF6850, 1) = 0 = 0
155712: __semop(15728650, 0x0FFFFFFFFFFF6890, 1) = 0 1
55712: __semop(15728650, 0x0FFFFFFFFFFF5920, 1)
278774: __semop(15728650, 0x0FFFFFFFFFFF6F10, 1)
155712: __semop(15728650, 0x0FFFFFFFFFFF6850, 1) = 0 = 0
278774: __semop(15728649, 0x0FFFFFFFFFFF7E40, 1)
114914: __semop(15728649, 0x0FFFFFFFFFFF6A80, 1) = 0 = 0
278774: __semop(15728650, 0x0FFFFFFFFFFF7E80, 1)
And when I saw a flood of semop's for any particular PID, a second later
in the 'topas' process list would show that PID at a 100% CPU ...
Most intriguing :)
Cheers,
Gavin.
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To: pgsql-performance@postgresql.org
Cc: gdh@laterooms.com
Subject: Re: pg 8.1.3, AIX, huge box, painfully slow.
In-Reply-To: <20060407232759.45581362.gdh@laterooms.com>
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