To: Gavin Hamill <gdh@laterooms.com>
cc: pgsql-performance@postgresql.org
Subject: Re: pg 8.1.3, AIX, huge box, painfully slow. 
In-reply-to: <20060407223635.9c4a0b38.gdh@laterooms.com> 
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>
Comments: In-reply-to Gavin Hamill <gdh@laterooms.com>
	message dated "Fri, 07 Apr 2006 22:36:35 +0100"
Date: Fri, 07 Apr 2006 17:56:49 -0400
Message-ID: <17055.1144447009@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

Gavin Hamill <gdh@laterooms.com> writes:
> There's truss installed which seems to do the same as strace on
> Linux... and here's a wildly non-scientific  glance..  I watched the
> 'topas' output (top for AIX) , identified a PID that was doing a lot of
> work, then attached truss to that pid. In addition to lots of send
> (), recv() and lseek()s...

Those are good, they represent real work getting done.

> about once a minute I saw hundreds of calls
> to __semop() interspersed with _select(),

This is not good.  Did the semop storms coincide with visible slowdown?
(I'd assume so, but you didn't actually say...)

			regards, tom lane