Thread: effective_io_concurrency details
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
2010/5/26 pasman pasmański <pasman.p@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 > > -- > Sent via pgsql-general mailing list (pgsql-general@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-general > -- Cédric Villemain 2ndQuadrant http://2ndQuadrant.fr/ PostgreSQL : Expertise, Formation et Support
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 > > -- ================================================ Kenichiro Tanaka K.K.Ashisuto http://www.ashisuto.co.jp/english/index.html ================================================