Why O_SYNC is faster than fsync on ext3

I sent this to Bruce but forgot to cc pgsql-hackers, The patches are
likely to go into 2.6.6. People interested in extremely safe fsync
writes should also follow the IDE barrier thread and the true fsync() in
Linux on IDE thread

----- Forwarded message from Yusuf Goolamabbas <yusufg(at)outblaze(dot)com> -----

Date: Sat, 20 Mar 2004 20:52:34 +0800
From: Yusuf Goolamabbas <yusufg(at)outblaze(dot)com>
To: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
Subject: Your fsync thread on hackers
Message-ID: <20040320125234(dot)GA11221(at)outblaze(dot)com>

Bruce, haven't followed the thread completely. Accessing the web archive
is slow from Hong Kong but I just wanted to point you to this lkml post
which shows why O_SYNC is much faster than fsync (at least on ext3)

http://marc.theaimsgroup.com/?l=linux-kernel&m=107959907410443&w=2

There are some pending fsync speedups on XFS also. You might want to
consider pointing Tom to do this so he can get the Redhat/Fedora guys to
look at the patches

Hope this helps, Regards, Yusuf

----- End forwarded message -----

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