From: Robert Haas <robertmhaas@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Gregory Stark <stark@enterprisedb.com>
Cc: Alan Stange <stange@rentec.com>
Cc: Jignesh K. Shah <J.K.Shah@sun.com>
Cc: Greg Smith <gsmith@gregsmith.com>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: 8.4 Performance improvements: was Re: Proposal of tunable fix for scalability of 8.4
Date: Fri, 13 Mar 2009 22:37:37 -0400
Message-ID: <603c8f070903131937t1c33fa97k29e7d8d07fa2e83@mail.gmail.com> (raw)
In-Reply-To: <26666.1236996376@sss.pgh.pa.us>
References: <C5DDBB25.3333%scott@richrelevance.com>
<49B922C0.6050700@sun.com>
<alpine.GSO.2.01.0903121613270.1925@westnet.com>
<49BA5537.8060002@sun.com>
<87prgl4jbh.fsf@oxford.xeocode.com>
<49BA79A4.9030208@rentec.com>
<12431.1236965004@sss.pgh.pa.us>
<87d4ck50h1.fsf@oxford.xeocode.com>
<26666.1236996376@sss.pgh.pa.us>
On Fri, Mar 13, 2009 at 10:06 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Gregory Stark <stark@enterprisedb.com> writes:
>> Tom Lane <tgl@sss.pgh.pa.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.
I think 1 should mean no prefetching, rather than 0. If the number of
concurrent I/O requests was 0, that would mean you couldn't perform
any I/O at all.
...Robert
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To: pgsql-performance@postgresql.org
Cc: robertmhaas@gmail.com, tgl@sss.pgh.pa.us, stark@enterprisedb.com, stange@rentec.com, J.K.Shah@sun.com, gsmith@gregsmith.com
Subject: Re: 8.4 Performance improvements: was Re: Proposal of tunable fix for scalability of 8.4
In-Reply-To: <603c8f070903131937t1c33fa97k29e7d8d07fa2e83@mail.gmail.com>
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