From: Jens Axboe <axboe@suse.de>
To: "Paul A. Sumner" <paul@zanfx.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: High write latency, iowait, slow writes 2.6.9
Date: Thu, 13 Jan 2005 09:56:33 +0100 [thread overview]
Message-ID: <20050113085633.GE2815@suse.de> (raw)
In-Reply-To: <41E61C68.10801@zanfx.com>
On Wed, Jan 12 2005, Paul A. Sumner wrote:
> Thanks... I've tried the as, deadline and cfq schedulers. Deadline is
> giving me the best results. I've also tried tweaking the stuff in
> /sys/block/sda/queue/iosched/.
>
> For lack of a better way of describing it, it seems like something is
> thrashing.
I you have time, I would like you to try current BK with this patch:
http://www.kernel.org/pub/linux/kernel/people/axboe/patches/v2.6/2.6.11-rc1/cfq-time-slices-20.gz
You should enable CONFIG_IOPRIO_WRITE, it is in the io scheduler config
section, if you do a make oldconfig it should pop up for you. Boot with
elevator=cfq to select cfq.
A simple profile of the bad period would also be nice, along with
vmstat 1 info from that period. If you boot with profile=2, do:
# readprofile -r
# run bad workload
# readprofile | sort -nr +2 > result_file
And send that along with the logged vmstat 1 from that same period.
Oh, and lastly, remember to CC people on lkml when you respond, thanks.
--
Jens Axboe
next prev parent reply other threads:[~2005-01-13 8:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-01-12 5:54 High write latency, iowait, slow writes 2.6.9 Paul A. Sumner
2005-01-12 21:20 ` Miquel van Smoorenburg
2005-01-13 6:59 ` Paul A. Sumner
2005-01-13 8:56 ` Jens Axboe [this message]
2005-01-13 19:01 ` Paul A. Sumner
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