From: Xavier Roche <roche+kml2@exalead.com>
To: Erik Mouw <erik@harddisk-recovery.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Huge performance issue with cciss driver on HP DL385 servers (2.6.13 -> 2.6.17)
Date: Tue, 11 Jul 2006 16:38:30 +0200 [thread overview]
Message-ID: <44B3B7E6.7020902@exalead.com> (raw)
In-Reply-To: <20060711132231.GG9790@harddisk-recovery.com>
Erik Mouw a écrit :
> AFAIK buffers for direct IO need to be *page* aligned. Use something
> like:
> I guess you got away with it cause your 512 byte alignment happened to
> align on a page, but you shouldn't count on that. However...
This example was actually just a minimal example - the running test is
correctly aligned.
> You should check the return value of pwrite().
Also checked in the "real" stress program.
Note that this problem is hard to reproduce, and might be related to
very strange I/O (and/or DMA access) operation ordering. The fact that
the program must be run just after a reboot (or the problem is not
easily reproductible) is something really fishy.
prev parent reply other threads:[~2006-07-11 14:38 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-11 13:02 Huge performance issue with cciss driver on HP DL385 servers (2.6.13 -> 2.6.17) Xavier Roche
2006-07-11 13:22 ` Erik Mouw
2006-07-11 14:38 ` Xavier Roche [this message]
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