From: Chris Torek <chris.torek@windriver.com>
To: Dave Chinner <david@fromorbit.com>
Cc: xfs@oss.sgi.com
Subject: Re: question about xfs_fsync on linux
Date: Wed, 16 Jul 2008 15:58:55 -0600 [thread overview]
Message-ID: <200807162158.m6GLwtE00281@elf.torek.net> (raw)
In-Reply-To: Your message of "Tue, 15 Jul 2008 12:48:30 +1000." <20080715024830.GZ29319@disturbed>
>Well, you are pretty much on your own, then. Really, we cannot help
>diagnose problems on old kernels with a random set of backported
>patches in them.
Definitely understood. I just wanted to ask that original
question, really. I had assumed that the file system itself
had to start any dirty-page writes, having missed the top level
filemap_fdatawrite() call.
We finally got a test case and did a bunch of analysis, and it
turns out that the DB software is missing an fsync() call. Of
course XFS won't fsync the file if you don't *ask* it to!
As long as I am sending mail, there is something else I am curious
about though. While this is not XFS specific, I wonder if there
is any desire to have different background write frequencies on
different file systems. By default, mm/page-writeback.c will start
writebacks after a 30-second delay. One can tune this to any other
number (via /proc/sys/vm/dirty_{expire,writeback}_centisecs), but
this affects the entire system. It might be useful to be able
to tune this per-FS instead.
(On the other hand, perhaps if one really wants one's data journaled,
one should just use a data-journaling file system....)
Chris
next prev parent reply other threads:[~2008-07-16 21:57 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-14 22:13 question about xfs_fsync on linux Chris Torek
2008-07-14 23:03 ` Dave Chinner
2008-07-15 1:29 ` Chris Torek
2008-07-15 2:48 ` Dave Chinner
2008-07-16 21:58 ` Chris Torek [this message]
2008-07-17 0:22 ` Dave Chinner
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