From: jmerkey <jmerkey@utah-nac.org>
To: Jens Axboe <axboe@suse.de>
Cc: Holger Kiehl <Holger.Kiehl@dwd.de>,
Vojtech Pavlik <vojtech@suse.cz>,
linux-raid <linux-raid@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: Where is the performance bottleneck?
Date: Wed, 31 Aug 2005 09:59:39 -0600 [thread overview]
Message-ID: <4315D3EB.4000601@utah-nac.org> (raw)
In-Reply-To: <20050831171124.GH4018@suse.de>
512 is not enough. It has to be larger. I just tried 512 and it still
limits the data rates.
Jeff
Jens Axboe wrote:
>On Wed, Aug 31 2005, jmerkey wrote:
>
>
>>I have seen an 80GB/sec limitation in the kernel unless this value is
>>changed in the SCSI I/O layer
>>for 3Ware and other controllers during testing of 2.6.X series kernels.
>>
>>Change these values in include/linux/blkdev.h and performance goes from
>>80MB/S to over 670MB/S on the 3Ware controller.
>>
>>
>>//#define BLKDEV_MIN_RQ 4
>>//#define BLKDEV_MAX_RQ 128 /* Default maximum */
>>#define BLKDEV_MIN_RQ 4096
>>#define BLKDEV_MAX_RQ 8192 /* Default maximum */
>>
>>
>
>That's insane, you just wasted 1MiB of preallocated requests on each
>queue in the system!
>
>Please just do
>
># echo 512 > /sys/block/dev/queue/nr_requests
>
>after boot for each device you want to increase the queue size too. 512
>should be enough with the 3ware.
>
>
>
next prev parent reply other threads:[~2005-08-31 15:59 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-08-29 18:20 Where is the performance bottleneck? Holger Kiehl
2005-08-29 19:54 ` Mark Hahn
2005-08-30 19:08 ` Holger Kiehl
2005-08-30 23:05 ` Guy
2005-09-28 20:04 ` Bill Davidsen
2005-09-30 4:52 ` Guy
2005-09-30 5:19 ` dean gaudet
2005-10-06 21:15 ` Bill Davidsen
2005-08-29 20:10 ` Al Boldi
2005-08-30 19:18 ` Holger Kiehl
2005-08-31 10:30 ` Al Boldi
2005-08-29 23:09 ` Peter Chubb
[not found] ` <20050829202529.GA32214@midnight.suse.cz>
2005-08-30 20:06 ` Holger Kiehl
2005-08-31 7:11 ` Vojtech Pavlik
2005-08-31 7:26 ` Jens Axboe
2005-08-31 11:54 ` Holger Kiehl
2005-08-31 12:07 ` Jens Axboe
2005-08-31 13:55 ` Holger Kiehl
2005-08-31 14:24 ` Dr. David Alan Gilbert
2005-08-31 20:56 ` Holger Kiehl
2005-08-31 21:16 ` Dr. David Alan Gilbert
2005-08-31 16:20 ` Jens Axboe
2005-08-31 15:16 ` jmerkey
2005-08-31 16:58 ` Tom Callahan
2005-08-31 15:47 ` jmerkey
2005-08-31 17:11 ` Jens Axboe
2005-08-31 15:59 ` jmerkey [this message]
2005-08-31 17:32 ` Jens Axboe
2005-08-31 16:51 ` Holger Kiehl
2005-08-31 17:35 ` Jens Axboe
2005-08-31 19:00 ` Holger Kiehl
2005-08-31 18:06 ` Michael Tokarev
2005-08-31 18:52 ` Ming Zhang
2005-08-31 18:57 ` Ming Zhang
2005-08-31 12:24 ` Nick Piggin
2005-08-31 16:25 ` Holger Kiehl
2005-08-31 17:25 ` Nick Piggin
2005-08-31 21:57 ` Holger Kiehl
2005-09-01 9:12 ` Holger Kiehl
2005-09-02 14:28 ` Al Boldi
2005-08-31 13:38 ` Holger Kiehl
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