From: Jens Axboe <jens.axboe@oracle.com>
To: Christoph Hellwig <hch@infradead.org>,
Kiyoshi Ueda <k-ueda@ct.jp.nec.com>,
agk@redhat.com, mchristi@redhat.com,
linux-kernel@vger.kernel.org, dm-devel@redhat.com,
j-nomura@ce.jp.nec.com
Subject: Re: [RFC PATCH 1/8] rqbased-dm: allow blk_get_request() to be called from interrupt context
Date: Fri, 22 Dec 2006 18:32:22 +0100 [thread overview]
Message-ID: <20061222173220.GU17199@kernel.dk> (raw)
In-Reply-To: <20061222140139.GA26033@infradead.org>
On Fri, Dec 22 2006, Christoph Hellwig wrote:
> On Wed, Dec 20, 2006 at 12:50:02PM -0500, Kiyoshi Ueda wrote:
> > Because I'd like to use blk_get_request() in q->request_fn()
> > which can be called from interrupt context like below:
> > scsi_io_completion -> scsi_end_request -> scsi_next_command
> > -> scsi_run_queue -> blk_run_queue -> q->request_fn
>
> > Or request should not be allocated in q->request_fn() anyway?
> > Do you have any other ideas?
>
> The right long-term fix is to make sure request_fn is only ever called
> from process context. This means moving retry handling to a thread instead
> of a softirq, but this will need careful performance testing and tweaking.
It's a lot more than just retry handling. Most driver reinvoke queueing
from the completion handling, so basically most of the time request_fn
is run from either softirq (like SCSI) or interrupt context (like IDE).
--
Jens Axboe
prev parent reply other threads:[~2006-12-22 17:30 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-12-19 22:11 [RFC PATCH 1/8] rqbased-dm: allow blk_get_request() to be called from interrupt context Kiyoshi Ueda
2006-12-20 13:48 ` Jens Axboe
2006-12-20 17:50 ` Kiyoshi Ueda
2006-12-20 18:49 ` Jens Axboe
2006-12-20 21:55 ` Kiyoshi Ueda
2006-12-21 7:53 ` Jens Axboe
2006-12-21 17:59 ` [dm-devel] " Mike Christie
2006-12-21 18:13 ` Mike Christie
2006-12-21 18:24 ` Jens Axboe
2006-12-21 18:30 ` Mike Christie
2006-12-21 18:36 ` Mike Christie
2006-12-21 18:42 ` Jens Axboe
2006-12-21 18:57 ` Mike Christie
2006-12-21 19:19 ` Jens Axboe
2006-12-21 22:22 ` Mike Christie
2006-12-21 18:40 ` Jens Axboe
2006-12-21 18:11 ` Kiyoshi Ueda
2006-12-21 18:21 ` Jens Axboe
2006-12-20 19:11 ` Chen, Kenneth W
2006-12-20 19:17 ` Jens Axboe
2006-12-22 14:01 ` Christoph Hellwig
2006-12-22 17:32 ` Jens Axboe [this message]
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