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Date: Fri, 13 Feb 2004 13:05:43 +1100
From: Nick Piggin <piggin@cyberone.com.au>
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To: Jamie Lokier <jamie@shareable.org>
CC: Helge Hafting <helgehaf@aitel.hist.no>, Valdis.Kletnieks@vt.edu,
       Michael Frank <mhf@linuxmail.org>, Giuliano Pochini <pochini@shiny.it>,
       Andrea Arcangeli <andrea@suse.de>, linux-kernel@vger.kernel.org
Subject: Re: ext2/3 performance regression in 2.6 vs 2.4 for small interl
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Jamie Lokier wrote:

>Helge Hafting wrote:
>
>>Something similiar could be done for io niceness.  If we run out of
>>normal priority io, how about not issuing the low priority io
>>right away.  Anticipate there will be more high-priority io
>>and wait for some idle time before letting low-priority
>>requests through.  And of course some maximum wait to prevent
>>total starvation.
>>
>
>The problem is quite similar to scheduling for quality on a network
>device.  Once a packet has started going it, usually you cannot abort
>the packet for a higher priority one.
>
>I thought there was a CBQ I/O scheduling patch or such to offer some
>kind of I/O niceness these days?
>
>

Yeah its Jens' CFQ io scheduler. It is in -mm, and I think it
has adjustable priorities now.

I have plans to do IO priorities in the anticipatory scheduler
(significantly differently to CFQ). One day...