From: Jens Axboe <axboe@kernel.dk>
To: "Georg Schönberger" <gschoenberger@thomas-krenn.com>
Cc: fio@vger.kernel.org
Subject: Re: IO Scheduler Diagrams
Date: Fri, 05 Oct 2012 13:40:25 +0200 [thread overview]
Message-ID: <506EC729.8040201@kernel.dk> (raw)
In-Reply-To: <1336570145.255301.1349430116859.JavaMail.root@thomas-krenn.com>
On 2012-10-05 11:41, Georg Schönberger wrote:
> Hello,
>
> this topic is not directly connected to Fio but nevertheless reasonable for all Fio Users.
> I am currently working on IO Scheduler Diagrams explaining how they process IO requests.
>
> Attached you find my first draft, I've already had some input from Christoph Hellwig. I would be happy
> if I get more feedback as I am not sure if everything is correct, especially with CFQ I had some problems drawing it.
Two comments:
- For deadline, the FIFO queues are just for tracking the ordering of
the requests. They serve no other purpose than to restart the position
inside the sorted tree (which is a tree, btw, it's not a linked list or
FIFO as the diagram would lead you to believe).
- For CFQ, the async queues are per-disk and split in prio classes and
priorities. The sync queues are per-process per-disk. Your graphic
doesn't really show that, it's a fairly complex relationsship.
--
Jens Axboe
prev parent reply other threads:[~2012-10-05 11:41 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1756305799.255171.1349429682456.JavaMail.root@thomas-krenn.com>
2012-10-05 9:41 ` IO Scheduler Diagrams Georg Schönberger
2012-10-05 11:40 ` Jens Axboe [this message]
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