From: "Jeff V. Merkey" <jmerkey@wolfmountaingroup.com>
To: Max Waterman <davidmaxwaterman+kernel@fastmail.co.uk>
Cc: linux-kernel@vger.kernel.org
Subject: Re: io performance...
Date: Mon, 16 Jan 2006 00:32:19 -0700 [thread overview]
Message-ID: <43CB4C03.7070304@wolfmountaingroup.com> (raw)
In-Reply-To: <43CB4CC3.4030904@fastmail.co.uk>
[-- Attachment #1: Type: text/plain, Size: 643 bytes --]
Max Waterman wrote:
> Hi,
>
> I've been referred to this list from the linux-raid list.
>
> I've been playing with a RAID system, trying to obtain best bandwidth
> from it.
>
> I've noticed that I consistently get better (read) numbers from kernel
> 2.6.8
> than from later kernels.
To open the bottlenecks, the following works well. Jens will shoot me
for recommending this,
but it works well. 2.6.9 so far has the highest numbers with this fix.
You can manually putz
around with these numbers, but they are an artificial constraint if you
are using RAID technology
that caches ad elevators requests and consolidates them.
Jeff
[-- Attachment #2: blkdev.patch --]
[-- Type: text/x-patch, Size: 540 bytes --]
diff -Naur ./include/linux/blkdev.h ../linux-2.6.9/./include/linux/blkdev.h
--- ./include/linux/blkdev.h 2004-10-18 15:53:43.000000000 -0600
+++ ../linux-2.6.9/./include/linux/blkdev.h 2005-12-06 09:54:46.000000000 -0700
@@ -23,8 +23,10 @@
typedef struct elevator_s elevator_t;
struct request_pm_state;
-#define BLKDEV_MIN_RQ 4
-#define BLKDEV_MAX_RQ 128 /* Default maximum */
+//#define BLKDEV_MIN_RQ 4
+//#define BLKDEV_MAX_RQ 128 /* Default maximum */
+#define BLKDEV_MIN_RQ 4096
+#define BLKDEV_MAX_RQ 8192 /* Default maximum */
next prev parent reply other threads:[~2006-01-16 8:08 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-01-16 7:35 io performance Max Waterman
2006-01-16 7:32 ` Jeff V. Merkey [this message]
2006-01-17 13:57 ` Jens Axboe
2006-01-17 19:17 ` Jeff V. Merkey
2006-01-16 8:35 ` Pekka Enberg
2006-01-17 17:06 ` Phillip Susi
2006-01-18 7:24 ` Max Waterman
2006-01-18 15:19 ` Phillip Susi
2006-01-20 5:58 ` Max Waterman
2006-01-20 13:42 ` Ian Soboroff
2006-01-25 6:36 ` Max Waterman
2006-01-25 14:19 ` Ian Soboroff
2006-01-25 13:09 ` Bernd Eckenfels
2006-01-18 3:02 ` Max Waterman
2006-01-18 4:30 ` Jeff V. Merkey
2006-01-18 5:09 ` Max Waterman
2006-01-18 4:37 ` Jeff V. Merkey
2006-01-18 7:06 ` Max Waterman
2006-01-18 9:21 ` Alan Cox
2006-01-18 15:48 ` Phillip Susi
2006-01-18 16:25 ` Bartlomiej Zolnierkiewicz
2006-01-19 0:48 ` Adrian Bunk
2006-01-19 13:18 ` Max Waterman
[not found] <5vx8f-1Al-21@gated-at.bofh.it>
[not found] ` <5wbRY-3cF-3@gated-at.bofh.it>
[not found] ` <5wdKh-5wF-15@gated-at.bofh.it>
2006-01-19 1:58 ` Robert Hancock
2006-01-19 13:14 ` Max Waterman
2006-01-19 14:08 ` Alan Cox
2006-01-20 4:09 ` Max Waterman
2006-01-20 4:27 ` Alexander Samad
2006-01-20 12:52 ` Alan Cox
2006-01-19 11:39 Al Boldi
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