From: Nick Piggin <nickpiggin@yahoo.com.au>
To: jmerkey <jmerkey@utah-nac.org>
Cc: Andreas Hirstius <Andreas.Hirstius@cern.ch>,
lkml <linux-kernel@vger.kernel.org>
Subject: Re: Serious performance degradation on a RAID with kernel 2.6.10-bk7 and later
Date: Thu, 21 Apr 2005 11:11:51 +1000 [thread overview]
Message-ID: <1114045911.5182.2.camel@npiggin-nld.site> (raw)
In-Reply-To: <42668977.5060708@utah-nac.org>
On Wed, 2005-04-20 at 10:55 -0600, jmerkey wrote:
>
> For 3Ware, you need to chage the queue depths, and you will see
> dramatically improved performance. 3Ware can take requests
> a lot faster than Linux pushes them out. Try changing this instead, you
> won't be going to sleep all the time waiting on the read/write
> request queues to get "unstarved".
>
>
> /linux/include/linux/blkdev.h
>
> //#define BLKDEV_MIN_RQ 4
> //#define BLKDEV_MAX_RQ 128 /* Default maximum */
> #define BLKDEV_MIN_RQ 4096
> #define BLKDEV_MAX_RQ 8192 /* Default maximum */
>
BTW, don't do this. BLKDEV_MIN_RQ sets the size of the mempool
reserved requests and will only get slightly used in low memory
conditions, so most memory will probably be wasted.
Just change /sys/block/xxx/queue/nr_requests
Nick
next prev parent reply other threads:[~2005-04-21 1:16 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-04-20 17:37 Andreas Hirstius
2005-04-20 16:55 ` jmerkey
2005-04-20 18:04 ` Andreas Hirstius
2005-04-20 18:24 ` Andreas Hirstius
2005-04-20 19:17 ` jmerkey
2005-04-21 1:11 ` Nick Piggin [this message]
2005-04-21 8:32 ` Andreas Hirstius
[not found] ` <58cb370e05042102272ce70f2@mail.gmail.com>
2005-04-21 9:42 ` Bartlomiej ZOLNIERKIEWICZ
2005-04-21 11:30 ` Andreas Hirstius
2005-04-21 15:05 ` [Gelato-technical] " David Mosberger
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