From: Aaron Carroll <aaronc@gelato.unsw.edu.au>
To: Martin Steigerwald <ms@teamix.de>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Jens Axboe <jens.axboe@oracle.com>
Subject: Re: Documentation on CFQ iosched parameters
Date: Tue, 23 Sep 2008 13:15:21 +1000 [thread overview]
Message-ID: <48D85F49.4080001@gelato.unsw.edu.au> (raw)
In-Reply-To: <200809221715.33143.ms@teamix.de>
Martin Steigerwald wrote:
> Hi!
>
> I am searching documentation about CFQ io scheduler. I can't find it in linux
> 2.6.26 Documentation directory.
>
> I found about these in german[1]:
>
> back_seek_max:16384
> back_seek_penalty:2
> fifo_expire_async:250
> fifo_expire_sync:123
> quantum:4
>
> But I am completely missing about these:
>
> slice_async:40
Base length of an asynchronous queue timeslice (that is, how long the
queue has to dispatch requests each round). The actual timeslice
length is scaled by the I/O priority.
> slice_async_rq:2
The base number of requests per round for asynchronous queues. Like
slice_async, the actual maximum is a function of slice_async_rq and I/O
priority.
> slice_idle:6
How long to wait for processes to produce more I/O before switching
queues. This is for anticipation of sequential I/O, and more even disk
time distribution for processes doing back to back synchronous I/Os.
> slice_sync:100
Same as slice_async, but for synchronous requests.
next prev parent reply other threads:[~2008-09-23 3:15 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-22 15:15 Martin Steigerwald
2008-09-23 3:15 ` Aaron Carroll [this message]
2008-09-23 9:00 ` Jens Axboe
2008-09-23 9:26 ` Martin Steigerwald
2008-09-23 9:32 ` Jens Axboe
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