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Re: First set of OSDL Shared Mem scalability results, some

From: Curt Sampson <cjs(at)cynic(dot)net>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Kevin Brown <kevin(at)sysexperts(dot)com>,pgsql-performance(at)postgresql(dot)org
Subject: Re: First set of OSDL Shared Mem scalability results, some
Date: 2004-10-24 05:46:16
Message-ID: Pine.NEB.4.58.0410241442150.1004@angelic-vtfw.cvpn.cynic.net (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-performance
On Sat, 23 Oct 2004, Tom Lane wrote:

> Seems to me the overhead of any such scheme would swamp the savings from
> avoiding kernel/userspace copies ...

Well, one really can't know without testing, but memory copies are
extremely expensive if they go outside of the cache.

> the locking issues alone would be painful.

I don't see why they would be any more painful than the current locking
issues. In fact, I don't see any reason to add more locking than we
already use when updating pages.

cjs
-- 
Curt Sampson  <cjs(at)cynic(dot)net>   +81 90 7737 2974   http://www.NetBSD.org
     Make up enjoying your city life...produced by BIC CAMERA

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