From: Florian Weimer <fweimer@bfk.de>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-fsdevel@vger.kernel.org
Subject: Re: Does fsync() block read and write ops on the same file?
Date: Fri, 11 Dec 2009 12:53:11 +0000 [thread overview]
Message-ID: <824onxekp4.fsf@mid.bfk.de> (raw)
In-Reply-To: <20091211124224.GK30608@discord.disaster> (Dave Chinner's message of "Fri\, 11 Dec 2009 23\:42\:24 +1100")
* Dave Chinner:
>> I'm not concerned with fsync latency per se. It's going to take a
>> while to write a few GBs scattered across the file. However, it's
>> annoying that read operations on the same file (which can't even see
>> the effect of the fsync operation) are blocked, some times for more
>> than two minutes.
>
> If they are blocking for that long then sysrq-w during that period
> will tell us exactly where in what filesystem they are blocking on....
Interesting. Is it possible to trigger this from the hang timer?
From that, I've got two traces:
[307370.450502] Call Trace:
[307370.450555] [<ffffffff802aa9c8>] dput+0x1c/0xdd
[307370.450590] [<ffffffff8042a2e9>] __down_read+0x87/0xa1
[307370.450641] [<ffffffffa0276cd8>] :xfs:xfs_ilock+0x31/0x60
[307370.450684] [<ffffffffa029a208>] :xfs:xfs_read+0x147/0x21a
[307370.450718] [<ffffffff8029ae23>] do_sync_read+0xc9/0x10c
[307370.450750] [<ffffffff80246201>] autoremove_wake_function+0x0/0x2e
[307370.450787] [<ffffffff8029b614>] vfs_read+0xaa/0x152
[307370.450815] [<ffffffff8029b9f5>] sys_read+0x45/0x6e
[307370.450844] [<ffffffff8020beca>] system_call_after_swapgs+0x8a/0x8f
[307396.186071] Call Trace:
[307396.186128] [<ffffffff8042963d>] __mutex_lock_slowpath+0x64/0x9b
[307396.186160] [<ffffffff804294a2>] mutex_lock+0xa/0xb
[307396.186190] [<ffffffff8029b749>] generic_file_llseek+0x2a/0x8b
[307396.186219] [<ffffffff8029b8f8>] sys_lseek+0x40/0x60
[307396.186248] [<ffffffff8020beca>] system_call_after_swapgs+0x8a/0x8f
--
Florian Weimer <fweimer@bfk.de>
BFK edv-consulting GmbH http://www.bfk.de/
Kriegsstraße 100 tel: +49-721-96201-1
D-76133 Karlsruhe fax: +49-721-96201-99
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next prev parent reply other threads:[~2009-12-11 12:53 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-10 9:22 Does fsync() block read and write ops on the same file? Florian Weimer
2009-12-11 3:55 ` Dave Chinner
2009-12-11 8:53 ` Florian Weimer
2009-12-11 12:42 ` Dave Chinner
2009-12-11 12:53 ` Florian Weimer [this message]
2009-12-12 23:05 ` Dave Chinner
2009-12-11 13:21 ` Christoph Hellwig
2009-12-11 13:35 ` Florian Weimer
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