From: Jens Axboe <jens.axboe@oracle.com>
To: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Nick <gentuu@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] cfq: fix IOPRIO_CLASS_IDLE delays
Date: Tue, 6 Nov 2007 20:26:11 +0100 [thread overview]
Message-ID: <20071106192611.GS1767@kernel.dk> (raw)
In-Reply-To: <20071106200510.GA11435@tv-sign.ru>
On Tue, Nov 06 2007, Oleg Nesterov wrote:
> After the fresh boot:
>
> ionice -c3 -p $$
> echo cfq >> /sys/block/XXX/queue/scheduler
> dd if=/dev/XXX of=/dev/null bs=512 count=1
>
> Now dd hangs in D state and the queue is completely stalled for approximately
> INITIAL_JIFFIES + CFQ_IDLE_GRACE jiffies. This is because cfq_init_queue()
> forgets to initialize cfq_data->last_end_request.
Another good catch, thanks Oleg!
> (I guess this patch is not complete, overflow is still possible)
Hmm, where would it overflow?
--
Jens Axboe
next prev parent reply other threads:[~2007-11-06 19:26 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-06 20:05 [PATCH] cfq: fix IOPRIO_CLASS_IDLE delays Oleg Nesterov
2007-11-06 19:26 ` Jens Axboe [this message]
2007-11-07 13:48 ` Oleg Nesterov
2007-11-07 12:50 ` Jens Axboe
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