From: Christoph Hellwig <hch@infradead.org>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org,
Jeffle Xu <jefflexu@linux.alibaba.com>,
Mike Snitzer <snitzer@redhat.com>,
dm-devel@redhat.com, Hannes Reinecke <hare@suse.de>
Subject: Re: [PATCH V5 11/12] block: add poll_capable method to support bio-based IO polling
Date: Mon, 12 Apr 2021 10:38:56 +0100 [thread overview]
Message-ID: <20210412093856.GA978201@infradead.org> (raw)
In-Reply-To: <20210401021927.343727-12-ming.lei@redhat.com>
On Thu, Apr 01, 2021 at 10:19:26AM +0800, Ming Lei wrote:
> From: Jeffle Xu <jefflexu@linux.alibaba.com>
>
> This method can be used to check if bio-based device supports IO polling
> or not. For mq devices, checking for hw queue in polling mode is
> adequate, while the sanity check shall be implementation specific for
> bio-based devices. For example, dm device needs to check if all
> underlying devices are capable of IO polling.
>
> Though bio-based device may have done the sanity check during the
> device initialization phase, cacheing the result of this sanity check
> (such as by cacheing in the queue_flags) may not work. Because for dm
> devices, users could change the state of the underlying devices through
> '/sys/block/<dev>/io_poll', bypassing the dm device above. In this case,
> the cached result of the very beginning sanity check could be
> out-of-date. Thus the sanity check needs to be done every time 'io_poll'
> is to be modified.
I really don't think thi should be a method, and I really do dislike
how we have all this "if (is_mq)" junk. Why can't we have a flag on
the gendisk that signals if the device can support polling that
is autoamtically set for blk-mq and as-needed by bio based drivers?
And please move everything that significantly hanges things for the
mq based path to separate prep patches early in th series.
next prev parent reply other threads:[~2021-04-12 9:46 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-01 2:19 [PATCH V5 00/12] block: support bio based io polling Ming Lei
2021-04-01 2:19 ` [PATCH V5 01/12] block: add helper of blk_queue_poll Ming Lei
2021-04-01 2:19 ` [PATCH V5 02/12] block: add one helper to free io_context Ming Lei
2021-04-01 2:19 ` [PATCH V5 03/12] block: create io poll context for submission and poll task Ming Lei
2021-04-12 10:19 ` Christoph Hellwig
2021-04-01 2:19 ` [PATCH V5 04/12] block: add req flag of REQ_POLL_CTX Ming Lei
2021-04-01 2:19 ` [PATCH V5 05/12] block: add new field into 'struct bvec_iter' Ming Lei
2021-04-12 9:26 ` Christoph Hellwig
2021-04-13 9:36 ` Ming Lei
2021-04-01 2:19 ` [PATCH V5 06/12] block/mq: extract one helper function polling hw queue Ming Lei
2021-04-12 9:29 ` Christoph Hellwig
2021-04-01 2:19 ` [PATCH V5 07/12] block: prepare for supporting bio_list via other link Ming Lei
2021-04-12 10:18 ` Christoph Hellwig
2021-04-12 11:37 ` Ming Lei
2021-04-01 2:19 ` [PATCH V5 08/12] block: use per-task poll context to implement bio based io polling Ming Lei
2021-04-12 9:54 ` Christoph Hellwig
2021-04-12 10:20 ` Ming Lei
2021-04-12 10:29 ` Christoph Hellwig
2021-04-12 11:42 ` Ming Lei
2021-04-12 10:16 ` Christoph Hellwig
2021-04-12 10:37 ` Ming Lei
2021-04-01 2:19 ` [PATCH V5 09/12] blk-mq: limit hw queues to be polled in each blk_poll() Ming Lei
2021-04-01 2:19 ` [PATCH V5 10/12] block: add queue_to_disk() to get gendisk from request_queue Ming Lei
2021-04-12 12:52 ` Jens Axboe
2021-04-01 2:19 ` [PATCH V5 11/12] block: add poll_capable method to support bio-based IO polling Ming Lei
2021-04-12 9:38 ` Christoph Hellwig [this message]
2021-04-14 8:38 ` JeffleXu
2021-04-14 11:24 ` Ming Lei
2021-04-15 1:34 ` JeffleXu
2021-04-15 7:43 ` Ming Lei
2021-04-15 9:21 ` JeffleXu
2021-04-15 10:06 ` Ming Lei
2021-04-15 11:21 ` JeffleXu
2021-04-15 13:08 ` Ming Lei
2021-04-16 8:00 ` [PATCH] block: introduce QUEUE_FLAG_POLL_CAP flag Jeffle Xu
2021-04-16 8:42 ` JeffleXu
2021-04-16 9:07 ` Ming Lei
2021-04-16 10:20 ` JeffleXu
2021-04-17 14:06 ` JeffleXu
2021-04-19 2:21 ` Ming Lei
2021-04-19 5:40 ` JeffleXu
2021-04-19 13:36 ` Ming Lei
2021-04-20 7:25 ` JeffleXu
2021-04-01 2:19 ` [PATCH V5 12/12] dm: support IO polling for bio-based dm device Ming Lei
2021-04-09 15:39 ` [PATCH V5 00/12] block: support bio based io polling Ming Lei
2021-04-12 9:46 ` Christoph Hellwig
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