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Re: Defaulting wal_sync_method to fdatasync on Linux for 9.1?

From: Andres Freund <andres(at)anarazel(dot)de>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-performance(at)postgresql(dot)org, Josh Berkus <josh(at)agliodbs(dot)com>, Greg Smith <greg(at)2ndquadrant(dot)com>
Subject: Re: Defaulting wal_sync_method to fdatasync on Linux for 9.1?
Date: 2010-11-17 01:01:24
Message-ID: 201011170201.24782.andres@anarazel.de (view raw or flat)
Thread:
Lists: pgsql-performance
On Wednesday 17 November 2010 01:51:28 Tom Lane wrote:
> Andres Freund <andres(at)anarazel(dot)de> writes:
> > On Wednesday 17 November 2010 00:31:34 Tom Lane wrote:
> >> Well, we're not going to increase the default to gigabytes
> > 
> > Especially not as I don't think it will have any effect after
> > wal_segment_size as that will force a write-out anyway. Or am I
> > misremembering the implementation?
> 
> Well, there's a forced fsync after writing the last page of an xlog
> file, but I don't believe that proves that more than 16MB of xlog
> buffers is useless.  Other processes could still be busy filling the
> buffers.
Maybe I am missing something, but I think the relevant AdvanceXLInsertBuffer() 
is currently called with WALInsertLock held?

Andres


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Subject: Re: Defaulting wal_sync_method to fdatasync on Linux for 9.1?
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