Re: 8.4 Performance improvements: was Re: Proposal of tunable fix for scalability of 8.4

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Gregory Stark <stark(at)enterprisedb(dot)com>, Alan Stange <stange(at)rentec(dot)com>, "Jignesh K(dot) Shah" <J(dot)K(dot)Shah(at)Sun(dot)COM>, Greg Smith <gsmith(at)gregsmith(dot)com>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: 8.4 Performance improvements: was Re: Proposal of tunable fix for scalability of 8.4
Date: 2009-04-02 23:08:50
Message-ID: 200904022308.n32N8oF06653@momjian.us
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Tom Lane wrote:
> Gregory Stark <stark(at)enterprisedb(dot)com> writes:
> > Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
> >> Ugh. So apparently, we actually need to special-case Solaris to not
> >> believe that posix_fadvise works, or we'll waste cycles uselessly
> >> calling a do-nothing function. Thanks, Sun.
>
> > Do we? Or do we just document that setting effective_cache_size on Solaris
> > won't help?
>
> I assume you meant effective_io_concurrency. We'd still need a special
> case because the default is currently hard-wired at 1, not 0, if
> configure thinks the function exists. Also there's a posix_fadvise call
> in xlog.c that that parameter doesn't control anyhow.

The attached patch prevents the posix_fadvise() probe in configure on
Solaris, and adds a comment why. I have already documented why Solaris
can't do effective_io_concurrency.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +

Attachment Content-Type Size
/pgpatches/solaris text/x-diff 1.7 KB

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