Subject: fio rand read/write regression with 2.6.32-rc3
From: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
To: Jens Axboe <jens.axboe@oracle.com>
Cc: LKML <linux-kernel@vger.kernel.org>
Content-Type: text/plain
Date: Sat, 10 Oct 2009 13:48:44 +0800
Message-Id: <1255153724.25078.68.camel@ymzhang>
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1274
Lines: 37

Comparing with 2.6.23-rc1's result, fio rand read write has regression
on my 2*4 core stoakley machine (8GB memory) with a JBOD of 12 disks.

Every disk has 8 1-GB files. Start 8 sub-processes per disk and every
process random chooses a file on the disk to do 36 times of file read or
write on the file and then choose another file.


fio_mmap_rand_read_4k regresion is about 35%.
Bisect down to patch:
1d2235152dc745c6d94bedb550fea84cffdbf768 is first bad commit
commit 1d2235152dc745c6d94bedb550fea84cffdbf768
Author: Jens Axboe <jens.axboe@oracle.com>
Date:   Fri Oct 2 19:27:04 2009 +0200

    cfq-iosched: add a knob for desktop interactiveness


After I revert the patch against 2.6.23-rc3, fio_mmap_rand_read_4k regression
disappears.

fio_mmap_randrw_4k has less than 20% regression and reverting the patch
could restore performance.

On another stoakley machine with another JBOD, we see the similiar regression.

ffsb rand read/write has a bigger regression and reverting the patch
could restore performance.

Yanmin


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/