Re: Proposal of tunable fix for scalability of 8.4

From: Simon Riggs <simon(at)2ndQuadrant(dot)com>
To: Matthew Wakeling <matthew(at)flymine(dot)org>
Cc: "Jignesh K(dot) Shah" <J(dot)K(dot)Shah(at)Sun(dot)COM>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Proposal of tunable fix for scalability of 8.4
Date: 2009-03-18 23:07:34
Message-ID: 1237417654.3953.320.camel@ebony.2ndQuadrant
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On Wed, 2009-03-18 at 13:49 +0000, Matthew Wakeling wrote:
> On Wed, 18 Mar 2009, Jignesh K. Shah wrote:
> > I thought about that.. Except without putting a restriction a huge queue will cause lot of time spent in manipulating the lock
> > list every time. One more thing will be to maintain two list shared and exclusive and round robin through them for every time you
> > access the list so manipulation is low.. But the best thing is to allow flexibility to change the algorithm since some workloads
> > may work fine with one and others will NOT. The flexibility then allows to tinker for those already reaching the limits.
>
> Yeah, having two separate queues is the obvious way of doing this. It
> would make most operations really trivial. Just wake everything in the
> shared queue at once, and you can throw it away wholesale and allocate a
> new queue. It avoids a whole lot of queue manipulation.

Yes, that sounds good.

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

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