From: Christoph Hellwig <hch@infradead.org>
To: Hannes Reinecke <hare@suse.de>
Cc: Christoph Hellwig <hch@infradead.org>,
Mike Snitzer <snitzer@redhat.com>, Jeff Moyer <jmoyer@redhat.com>,
Jens Axboe <axboe@kernel.dk>, Shaohua Li <shli@fusionio.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/1] block: rework flush sequencing for blk-mq
Date: Fri, 14 Mar 2014 05:44:57 -0700 [thread overview]
Message-ID: <20140314124457.GA4859@infradead.org> (raw)
In-Reply-To: <5322CC4D.8040509@suse.de>
On Fri, Mar 14, 2014 at 10:30:53AM +0100, Hannes Reinecke wrote:
> That was actually one of my plans, move dm-multipath over to use
> blk-mq. But then I'd need to discuss with Jens et al how to best
> achieve this; the current static hctx allocation doesn't play well
> with multipaths dynamic path management.
I'd say it the other way around: the clone + insert hacks in
dm-multipath don't work well with blk-mq. Not allowing non-owned
requests is fundamentally part of the blk-mq model to allow things
like the integrated tag allocator and queue depth limiting or the
preallocated driver specific data.
Instead dm-multipath should alway resubmit the request like it already
does for the slow path for the first step. Longer term we might be able
to operate using a cheaper temporary structure, but I'm not sure that's
going to be worth it.
next prev parent reply other threads:[~2014-03-14 12:45 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-30 13:26 [PATCH 0/1] " Christoph Hellwig
2014-01-30 13:26 ` [PATCH 1/1] " Christoph Hellwig
2014-02-07 1:18 ` Shaohua Li
2014-02-07 14:19 ` Christoph Hellwig
2014-02-08 0:55 ` Shaohua Li
2014-02-10 10:33 ` Christoph Hellwig
2014-03-07 20:45 ` Jeff Moyer
2014-03-08 15:52 ` Christoph Hellwig
2014-03-08 17:33 ` Mike Snitzer
2014-03-08 19:51 ` Hannes Reinecke
2014-03-08 18:13 ` Mike Snitzer
2014-03-08 21:33 ` Hannes Reinecke
2014-03-08 22:09 ` [PATCH] block: fix q->flush_rq NULL pointer crash on dm-mpath flush Mike Snitzer
2014-03-09 0:24 ` Jens Axboe
2014-03-09 0:57 ` Mike Snitzer
2014-03-09 3:18 ` Jens Axboe
2014-03-09 3:29 ` Mike Snitzer
2014-03-12 10:28 ` [PATCH 1/1] block: rework flush sequencing for blk-mq Christoph Hellwig
2014-03-12 10:50 ` Hannes Reinecke
2014-03-12 10:55 ` Christoph Hellwig
2014-03-12 11:07 ` Hannes Reinecke
2014-03-12 11:00 ` SuSE O_DIRECT|O_NONBLOCK overload Christoph Hellwig
2014-03-13 0:15 ` NeilBrown
2014-03-14 17:46 ` Mike Christie
2014-03-13 16:13 ` [PATCH 1/1] block: rework flush sequencing for blk-mq Mike Snitzer
2014-03-14 9:25 ` Christoph Hellwig
2014-03-14 9:30 ` Hannes Reinecke
2014-03-14 12:44 ` Christoph Hellwig [this message]
2014-03-14 9:34 ` Christoph Hellwig
2014-03-14 9:52 ` Hannes Reinecke
2014-03-14 10:58 ` Christoph Hellwig
2014-03-14 11:10 ` Hannes Reinecke
2014-03-14 13:00 ` Mike Snitzer
2014-03-14 13:23 ` Christoph Hellwig
2014-03-14 14:13 ` Mike Snitzer
2014-03-15 13:28 ` scsi_debug and mutipath, was " Christoph Hellwig
2014-03-17 11:55 ` [dm-devel] " Bryn M. Reeves
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