linux-kernel - Re: [PATCH/RESEND v6 3/3] block: Adding ROW scheduling algorithm

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Date:	Mon, 13 May 2013 14:25:57 -0400
From:	Jeff Moyer <jmoyer@...hat.com>
To:	Tanya Brokhman <tlinder@...eaurora.org>
Cc:	axboe@...nel.dk, linux-arm-msm@...r.kernel.org,
	linux-mmc@...r.kernel.org,
	linux-doc@...r.kernel.org (open list:DOCUMENTATION),
	linux-kernel@...r.kernel.org (open list)
Subject: Re: [PATCH/RESEND v6 3/3] block: Adding ROW scheduling algorithm

Tanya Brokhman <tlinder@...eaurora.org> writes:

> This patch adds the implementation of a new scheduling algorithm - ROW.
> The policy of this algorithm is to prioritize READ requests over WRITE
> as much as possible without starving the WRITE requests.
> The requests are kept in queues according to their priority. The dispatch
> is done in a Round Robin manner with a different slice for each queue.
> READ request queues get bigger dispatch quantum than the write requests.

You have just described CFQ.

Last time I asked for performance numbers[1], you mentioned that you had
published some, but provided no pointers to a paper or mailing list
posting, and I wasn't able to find anything via google, either.

It sounds as though you haven't even tried to adapt CFQ to your needs
(you mentioned trying to tune it, but not what tunings you tried or what
the results were).  Continuing to position your new scheduler as the
only way forward without providing the data that led you to that
conclusion isn't very helpful.  Note that I'm not suggesting that your
conclusion is wrong.  Perhaps if you can provide a link to a research
paper, we can start there.  For now, I can't see why we should take on
the maintenance of another I/O scheduler.

Cheers,
Jeff

[1] https://lkml.org/lkml/2012/8/7/164
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