| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| 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: | 2009-03-14 02:37:37 |
| Message-ID: | 603c8f070903131937t1c33fa97k29e7d8d07fa2e83@mail.gmail.com |
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| Lists: | pgsql-performance |
On Fri, Mar 13, 2009 at 10:06 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> 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.
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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