[GENERAL] effective_io_concurrency details

2010-05-26 Thread pasman pasmański
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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Re: [GENERAL] effective_io_concurrency details

2010-05-26 Thread Cédric Villemain
2010/5/26 pasman pasmański pasma...@gmail.com:
 Hello.

 I have 2 questions:
 Is effective_io_concurrency working on WinXP sp2 ?

no

 and what is the difference between effective_io_concurrency = 0
 and effective_io_concurrency = 1

0 disable prefetching.
1 allow a short prefetch window



 Postgres 8.4.4
 
 pasman

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Re: [GENERAL] effective_io_concurrency details

2010-05-26 Thread Kenichiro Tanaka

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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