To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Ingo Molnar <mingo@elte.hu>, David Rees <drees76@gmail.com>,
       Jesper Krogh <jesper@krogh.cc>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Linux 2.6.29
From: Andi Kleen <andi@firstfloor.org>
References: <alpine.LFD.2.00.0903231617550.3032@localhost.localdomain>
	<49C87B87.4020108@krogh.cc>
	<72dbd3150903232346g5af126d7sb5ad4949a7b5041f@mail.gmail.com>
	<20090324091545.758d00f5@lxorguk.ukuu.org.uk>
	<20090324093245.GA22483@elte.hu>
	<20090324101011.6555a0b9@lxorguk.ukuu.org.uk>
In-Reply-To: <20090324101011.6555a0b9@lxorguk.ukuu.org.uk> (Alan Cox's message of "Tue, 24 Mar 2009 10:10:11 +0000")
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Date: Tue, 24 Mar 2009 13:27:44 +0100
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Alan Cox <alan@lxorguk.ukuu.org.uk> writes:

>> > I have not had this problem since I applied Arjan's (for some reason
>> > repeatedly rejected) patch to change the ioprio of the various writeback
>> > daemons. Under some loads changing to the noop I/O scheduler also seems
>> > to help (as do most of the non default ones)
>> 
>> (link would be useful)
>
>
> "Give kjournald a IOPRIO_CLASS_RT io priority"
>
> October 2007 (yes its that old)

One issue discussed back then (also for a similar XFS patch) was
that having the kernel use the RT priorities by default makes
them useless as user override.

The proposal was to have a new priority level between normal and RT
for this, but noone implemented this.

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only.
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