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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Brad Nicholson <bnichols@ca.afilias.info>
Cc: Greg Smith <greg@2ndquadrant.com>
Cc: André Volpato <andre.volpato@ecomtecnologia.com.br>
Cc: pgsql-performance@postgresql.org
Subject: Re: AIX slow buffer reads
Date: Wed, 27 Oct 2010 18:44:59 -0400
Message-ID: <29868.1288219499@sss.pgh.pa.us> (raw)
In-Reply-To: <4CC8A9A3.7060901@ca.afilias.info>
References: <1141414014.10692.1288199109474.JavaMail.root@zimbra01a>
	<4CC87C69.5070301@2ndquadrant.com>
	<26542.1288210215@sss.pgh.pa.us>
	<4CC8A9A3.7060901@ca.afilias.info>

Brad Nicholson <bnichols@ca.afilias.info> writes:
> On 10/27/2010 4:10 PM, Tom Lane wrote:
>> AFAICT from googling, AIX does have posix_fadvise, though maybe it
>> doesn't do anything useful ...

> If there is an easy way to check if it does do anything useful?  If so, 
> I can check it out.

If you don't see any performance change in bitmap scans between
effective_io_concurrency = 0 and effective_io_concurrency = maybe 4 or
so, then you could probably conclude it's a no-op.

			regards, tom lane



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