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From: Andrew Morton <akpm@zip.com.au>
To: Oliver Paukstadt <pstadt@stud.fh-heilbronn.de>
Cc: Matti Aarnio <matti.aarnio@zmailer.org>,
	Linux-Kernel <linux-kernel@vger.kernel.org>,
	linux-raid@vger.kernel.org
Subject: Re: 2.4.17 RAID-1 EXT3  reliable to hang....
Date: Mon, 07 Jan 2002 00:49:30 -0800	[thread overview]
Message-ID: <3C39611A.F5C9BD3@zip.com.au> (raw)
In-Reply-To: <3C395A2C.B7A24844@zip.com.au> <Pine.LNX.4.33.0201070933590.4076-100000@lola.stud.fh-heilbronn.de>

Oliver Paukstadt wrote:
> 
> Heavy traffic on ext3 seems to cause short system freezes.

This could be due to disk request elevator latency and VM imbalance.
Your application has a page dropped due to the competing write activity,
and it takes ages to be restored, due to the write activity.
 
> Seems only to happen on 2 or more processor boxes.

In which case the above theory is wrong.
 
> I'm not deep into kernel nor ext3, but how is the journal flushed if
> full?

Nothing special, really - we just pump a stream of data out to disk.
While this is happening, other processes can still attach data to the
journal without getting blocked.  Up to a point.  Our handling of this
is a bit sudden at present.  Some people have reported benefit from
radically decreasing the buffer flushtimes. See Daniel Robbins' article
at http://www-106.ibm.com/developerworks/linux/library/l-fs8/ for this.
Yes, improvements are needed in this area.  Not only in ext3.

You haven't really defined "freeze", but it's certainly different
from Matti's freeze.

-

  reply	other threads:[~2002-01-07  8:55 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-01-04 14:36 2.4.17 RAID-1 EXT3 reliable to hang Matti Aarnio
2002-01-07  8:00 ` Matti Aarnio
2002-01-07  8:19   ` Andrew Morton
2002-01-07  8:38     ` Matti Aarnio
2002-01-07  8:39     ` Oliver Paukstadt
2002-01-07  8:49       ` Andrew Morton [this message]
2002-01-07  9:51       ` Richard Guenther
2002-01-07 10:09         ` Andrew Morton
2002-01-07 10:33           ` Richard Guenther
2002-01-20 17:31           ` Matti Aarnio
2002-01-20 19:24             ` John Jasen
2002-01-20 19:57               ` Matti Aarnio
2002-01-21  0:22                 ` Oliver Xymoron
2002-01-07 13:45         ` Alan Cox

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