From: David Chinner <dgc@sgi.com>
To: Robin Holt <holt@sgi.com>
Cc: Andrew Morton <akpm@osdl.org>,
john@johnmccutchan.com, linux-kernel@vger.kernel.org,
rml@novell.com, arnd@arndb.de, hch@lst.de
Subject: Re: udevd is killing file write performance.
Date: Fri, 24 Feb 2006 00:42:13 +1100 [thread overview]
Message-ID: <20060223134213.GG1332401@melbourne.sgi.com> (raw)
In-Reply-To: <20060223125639.GB25007@lnx-holt.americas.sgi.com>
On Thu, Feb 23, 2006 at 06:56:39AM -0600, Robin Holt wrote:
> On Wed, Feb 22, 2006 at 12:05:47PM -0800, Andrew Morton wrote:
> > Robin Holt <holt@sgi.com> wrote:
> > >
> > > Let me reiterate, I know _VERY_ little about filesystems. Can the
> > > dentry->d_lock be changed to a read/write lock?
> >
> > Well, it could, but I suspect that won't help - the hold times in there
> > will be very short so the problem is more likely acquisition frequency.
> >
> > However it's a bit strange that this function is the bottleneck. If their
> > workload is doing large numbers of reads or writes from large numbers of
> > processes against the same file then they should be hitting heavy
> > contention on other locks, such as i_sem and/or tree_lock and/or lru_lock
> > and others.
> >
> > Can you tell us more about the kernel-visible behaviour of this app?
>
> I looked at a little more of the output. All I have to go on is a few
> back traces generated by kdb of the entire system a few seconds apart.
>
> In all of the traces, the first chunk of cpus are the only ones doing
> writes. I have not counted exactly, but I think it is around 32. There
> may be more or less, but that is the feeling (sometimes they are doing
> reads as well).
Robin, is the app doing direct or buffered I/O?
Cheers,
Dave.
--
Dave Chinner
R&D Software Enginner
SGI Australian Software Group
next prev parent reply other threads:[~2006-02-23 13:42 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-02-22 13:42 udevd is killing file write performance Robin Holt
2006-02-22 13:55 ` Andrew Morton
2006-02-22 16:48 ` John McCutchan
2006-02-22 17:50 ` Robin Holt
2006-02-22 20:05 ` Andrew Morton
2006-02-22 21:50 ` Jeff V. Merkey
2006-02-23 12:56 ` Robin Holt
2006-02-23 13:42 ` David Chinner [this message]
2006-02-22 22:52 ` John McCutchan
2006-02-22 23:12 ` Andrew Morton
2006-02-22 23:41 ` John McCutchan
2006-02-24 0:14 ` Andrew Morton
2006-02-24 0:14 ` Andrew Morton
2006-02-24 5:47 ` John McCutchan
2006-02-24 6:00 ` Andrew Morton
2006-02-24 7:07 ` Nick Piggin
2006-02-24 7:16 ` Andrew Morton
2006-02-24 7:19 ` Nick Piggin
2006-02-26 16:58 ` John McCutchan
2006-02-24 18:56 ` Robin Holt
2006-02-25 2:44 ` Nick Piggin
2006-02-25 15:53 ` [patch] inotify: lock avoidance with parent watch status in dentry Nick Piggin
2006-02-28 0:48 ` Andrew Morton
2006-02-26 16:55 ` udevd is killing file write performance John McCutchan
2006-02-27 10:11 ` Nick Piggin
2006-02-27 20:17 ` John McCutchan
2006-02-23 20:38 ` Benjamin LaHaise
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