Re: effective_io_concurrency details - Mailing list pgsql-general

Hello.

 >Is effective_io_concurrency working on WinXP sp2 ?
No.
"effective_io_concurrency"  works when an OS can use posix_fadvise().
But I think WinXP  doesn't have posix_fadvise().

 >and what is the difference between effective_io_concurrency = 0
 >and effective_io_concurrency = 1
If effective_io_concurrency = 0,PostgreSQL never uses PREFETCH.
On my environment, my PostgreSQL doesn't start up when
effective_io_concurrency=1.
#My environment WinXP sp2 and PostgreSQL is 8.4.4, too.

What I referenced)
http://archives.postgresql.org/pgsql-hackers/2009-03/msg00911.php

http://doxygen.postgresql.org/bufmgr_8c-source.html#l00075
pgsql/src/backend/storage/buffer/bufmgr.c
00070 /*
00071  * How many buffers PrefetchBuffer callers should try to stay
ahead of their
00072  * ReadBuffer calls by.  This is maintained by the assign hook for
00073  * effective_io_concurrency.  Zero means "never prefetch".
00074  */

> Hello.
>
> I have 2 questions:
> Is effective_io_concurrency working on WinXP sp2 ?
> and what is the difference between effective_io_concurrency = 0
> and effective_io_concurrency = 1
>
>
> Postgres 8.4.4
> ------------
> pasman
>
>


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Kenichiro Tanaka
K.K.Ashisuto
http://www.ashisuto.co.jp/english/index.html
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