Subject: Re: Proposal of tunable fix for scalability of 8.4
From: Simon Riggs <simon@2ndQuadrant.com>
To: "Jignesh K. Shah" <J.K.Shah@Sun.COM>
Cc: Tom Lane <tgl@sss.pgh.pa.us>,
 Kevin Grittner <Kevin.Grittner@wicourts.gov>,
	pgsql-performance@postgresql.org
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	<1237330778.3953.139.camel@ebony.2ndQuadrant>
	<49C0384E.2020707@sun.com>
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Date: Wed, 18 Mar 2009 00:43:23 +0000
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On Tue, 2009-03-17 at 19:54 -0400, Jignesh K. Shah wrote:
> 
> Simon Riggs wrote:
> > On Tue, 2009-03-17 at 17:41 -0400, Jignesh K. Shah wrote:
> >
> >   
> >> I did a quick test with patch. Unfortunately it improves my number
> >> even with default setting 0 (not sure whether I should be pleased or
> >> sad - Definitely no overhead infact seems to help performance a bit.
> >> NOTE: Logic is same, implementation is slightly different for default
> >> set)
> >>     
> >
> > OK, I bite. 25% gain from doing nothing??? You're stretching my... err,
> > credulity.
> >
> > I like the train of thought for setting 1 and it is worth investigating,
> > but something feels wrong somewhere.
> >
> >   
> Actually I think I am hurting my credibility here  since I cannot 
> explain the improvement with the patch but still using default logic 
> (thought different way I compare sequential using fields from the 
> previous proc structure  instead of comparing with constant boolean)  
> But the change was necessary to allow it to handle multiple algorithms 
> and yet be sleek and not bloated.
> 
>  In next couple of weeks I plan to test the patch on a different x64 
> based system to do a sanity testing on lower number of cores and also 
> try out other workloads ...

Good plan. I'm behind your ideas and will be happy to wait.

-- 
 Simon Riggs           www.2ndQuadrant.com
 PostgreSQL Training, Services and Support