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From: Andrew Morton <akpm@zip.com.au>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Alexander Moibenko <moibenko@fnal.gov>, linux-kernel@vger.kernel.org
Subject: Re: fsync delays for a long time.
Date: Thu, 14 Feb 2002 13:20:57 -0800	[thread overview]
Message-ID: <3C6C2A39.38ED19B1@zip.com.au> (raw)
In-Reply-To: <3C6C2342.5044B738@zip.com.au> from "Andrew Morton" at Feb 14, 2002 12:51:14 PM <E16bT7y-00017B-00@the-village.bc.nu>

Alan Cox wrote:
> 
> > > fsync on a very large file is very slow on the 2.2 kernels
> >
> > This could very well be due to request allocation starvation.
> > fsync is sleeping in __get_request_wait() while bonnie keeps
> > on stealing all the requests.
> 
> That may amplify it but in the 2.2 case fsync on any sensible sized file
> is already horribly performing. It hits databases like solid quite badly

I'm surprised.  ext2's fsync in 2.2 is in fact quite optimal: a single
pass across the block tree, in probable-LBA-order.  No livelock potential
there.  Optimal.  Note that it implements "only sync the stuff which was
dirty on entry" semantics.

But msync() is a different kettle of fish.  It calls file_fsync(), which
syncs the entire device, livelockably.  Are you sure `solid' is not
using msync?

-

  parent reply	other threads:[~2002-02-14 21:22 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-02-14 16:03 fsync delays for a long time Alexander Moibenko
2002-02-14 17:39 ` Alan Cox
2002-02-14 20:51   ` Andrew Morton
2002-02-14 21:09     ` Alan Cox
2002-02-14 21:12       ` Alexander Moibenko
2002-02-14 21:37         ` Alan Cox
2002-02-14 21:26           ` Alexander Moibenko
2002-02-14 21:41             ` Andrew Morton
2002-02-14 22:18               ` Alexander Moibenko
2002-02-14 21:20       ` Andrew Morton [this message]
2002-02-14 21:38         ` Alan Cox
2002-02-15 16:48         ` Stephen C. Tweedie
2002-02-15 17:24     ` Simon Kirby
2002-02-15 19:07       ` Andrew Morton
2002-02-15 19:21         ` Simon Kirby
2002-02-17 12:47       ` Bill Davidsen
2002-02-17 16:45         ` Simon Kirby

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