From: Jens Axboe <jens.axboe@oracle.com>
To: ???? <xiegang112@gmail.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: The difference of request dir between AS and Deadline I/O scheduler?
Date: Mon, 2 Mar 2009 13:25:48 +0100 [thread overview]
Message-ID: <20090302122547.GT11787@kernel.dk> (raw)
In-Reply-To: <d364733c0903012106g2625d433o4cdbbbcc5a9ff19a@mail.gmail.com>
On Mon, Mar 02 2009, ???? wrote:
> Hi,
>
> I'm little confused about the defination of request dir in AS and
> Deadline I/O scheduler.
> In AS, the request dir is defined by wheher it's sync:
>
> data_dir = rq_is_sync(rq);
>
> But in Deadline, the requests are grouped by read and write.
>
> Why is there the difference since AS is an extension of Deadline?
> what's the consideration?
Because AS uses the sync vs async distinction to decide whether to
anticipate a new request from that process. 'sync' is then reads or sync
writes, whereas deadline does not distinguish between sync and async
writes.
--
Jens Axboe
next prev parent reply other threads:[~2009-03-02 12:25 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-02 5:06 The difference of request dir between AS and Deadline I/O scheduler? 谢纲
2009-03-02 12:25 ` Jens Axboe [this message]
2009-03-02 13:03 ` 谢纲
2009-03-02 13:13 ` Jens Axboe
2009-03-03 4:21 ` Aaron Carroll
2009-03-03 4:52 ` 谢纲
2009-03-03 4:58 ` Aaron Carroll
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