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From: Ming Lei <ming.lei@redhat.com>
To: Keith Busch <kbusch@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>,
	Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org, Sagi Grimberg <sagi@grimberg.me>,
	Baolin Wang <baolin.wang7@gmail.com>
Subject: Re: [PATCH 3/9] blk-mq: don't predicate last flag in blk_mq_dispatch_rq_list
Date: Thu, 14 May 2020 16:28:10 +0800	[thread overview]
Message-ID: <20200514082810.GL2073570@T590> (raw)
In-Reply-To: <20200514032143.GA1833@redsun51.ssa.fujisawa.hgst.com>

On Thu, May 14, 2020 at 12:21:43PM +0900, Keith Busch wrote:
> On Thu, May 14, 2020 at 10:09:55AM +0800, Ming Lei wrote:
> > However, why is .commit_rqs() required? Why doesn't .queue_rq() handle the batching
> > submission before non-STS_OK is returned?
> 
> Wouldn't the driver need to know that the request is !first in that case
> so that it doesn't commit nothing if the first request fails?

Yeah, I have replied on this question, :-)

In short, I plan to make the interface explicit and more efficient:

1) .commit_rqs() is used for notifying driver that one batching requests
are done, which is usually caused by lacking of resource for queuing more
requests to driver

2) one request with .last flag marks end of one batching submission, so
.commit_rq() will not be called if no new request with !.last is queued

3) it is driver's responsibility for handling batching submission if non
STS_OK is returned from .queue_rq() to block layer.

Then we can minimize .commit_rqs() uses.

Thanks,
Ming


  reply	other threads:[~2020-05-14  8:28 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-13  9:54 [PATCH 0/9] blk-mq: support batching dispatch from scheduler Ming Lei
2020-05-13  9:54 ` [PATCH 1/9] blk-mq: pass request queue into get/put budget callback Ming Lei
2020-05-13 10:06   ` Johannes Thumshirn
2020-05-13 12:24   ` Christoph Hellwig
2020-05-13 14:36   ` Doug Anderson
2020-05-13 22:48   ` Sagi Grimberg
2020-05-13  9:54 ` [PATCH 2/9] blk-mq: pass hctx to blk_mq_dispatch_rq_list Ming Lei
2020-05-13 12:26   ` Christoph Hellwig
2020-05-13 22:49   ` Sagi Grimberg
2020-05-13  9:54 ` [PATCH 3/9] blk-mq: don't predicate last flag in blk_mq_dispatch_rq_list Ming Lei
2020-05-13 12:27   ` Christoph Hellwig
2020-05-14  0:50     ` Ming Lei
2020-05-14  5:50       ` Christoph Hellwig
2020-05-14  2:09     ` Ming Lei
2020-05-14  2:19       ` Ming Lei
2020-05-14  3:21       ` Keith Busch
2020-05-14  8:28         ` Ming Lei [this message]
2020-05-13  9:54 ` [PATCH 4/9] blk-mq: move getting driver tag and bugget into one helper Ming Lei
2020-05-13 12:37   ` Christoph Hellwig
2020-05-13 22:54   ` Sagi Grimberg
2020-05-13  9:54 ` [PATCH 5/9] blk-mq: move .queue_rq code " Ming Lei
2020-05-13 12:38   ` Christoph Hellwig
2020-05-13  9:54 ` [PATCH 6/9] blk-mq: move code for handling partial dispatch " Ming Lei
2020-05-13 12:56   ` Christoph Hellwig
2020-05-13 13:01     ` Christoph Hellwig
2020-05-14  1:25       ` Ming Lei
2020-05-13  9:54 ` [PATCH 7/9] blk-mq: remove dead check from blk_mq_dispatch_rq_list Ming Lei
2020-05-13 12:57   ` Christoph Hellwig
2020-05-13 23:24   ` Sagi Grimberg
2020-05-13  9:54 ` [PATCH 8/9] blk-mq: pass obtained budget count to blk_mq_dispatch_rq_list Ming Lei
2020-05-13 13:26   ` Christoph Hellwig
2020-05-13  9:54 ` [PATCH 9/9] blk-mq: support batching dispatch in case of io scheduler Ming Lei
2020-05-23  7:45 ` [PATCH 0/9] blk-mq: support batching dispatch from scheduler Baolin Wang
2020-05-25  2:17   ` Ming Lei

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