From: Jens Axboe <axboe@kernel.dk>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-block@vger.kernel.org, Josef Bacik <josef@toxicpanda.com>
Subject: Re: [PATCH 03/11] blk-rq-qos: inline check for q->rq_qos functions
Date: Fri, 16 Nov 2018 08:18:17 -0700 [thread overview]
Message-ID: <eef6cddf-c38e-f741-7f64-43d9c55bfd0e@kernel.dk> (raw)
In-Reply-To: <20181116083839.GE9023@infradead.org>
On 11/16/18 1:38 AM, Christoph Hellwig wrote:
> On Thu, Nov 15, 2018 at 12:51:27PM -0700, Jens Axboe wrote:
>> Put the short code in the fast path, where we don't have any
>> functions attached to the queue. This minimizes the impact on
>> the hot path in the core code.
>
> This looks mechanically fine:
>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
>
> But since I seem to have missed the introduction of it - why do we need
> multiple struct rq_qos per request to start with? This sort of stacking
> seems rather odd and counter-productive, and the commit introducing
> this code doesn't explain the rationale at all.
Per request-queue, not per request. One would be iolatency, one would
be wbt, etc.
--
Jens Axboe
next prev parent reply other threads:[~2018-11-16 15:18 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-15 19:51 [PATCHSET v2 0/11] Various block optimizations Jens Axboe
2018-11-15 19:51 ` [PATCH 01/11] nvme: provide optimized poll function for separate poll queues Jens Axboe
2018-11-16 8:35 ` Christoph Hellwig
2018-11-16 15:22 ` Jens Axboe
2018-11-15 19:51 ` [PATCH 02/11] block: add queue_is_mq() helper Jens Axboe
2018-11-16 8:35 ` Christoph Hellwig
2018-11-15 19:51 ` [PATCH 03/11] blk-rq-qos: inline check for q->rq_qos functions Jens Axboe
2018-11-16 8:38 ` Christoph Hellwig
2018-11-16 15:18 ` Jens Axboe [this message]
2018-11-15 19:51 ` [PATCH 04/11] block: avoid ordered task state change for polled IO Jens Axboe
2018-11-16 8:41 ` Christoph Hellwig
2018-11-16 15:32 ` Jens Axboe
2018-11-15 19:51 ` [PATCH 05/11] block: add polled wakeup task helper Jens Axboe
2018-11-16 8:41 ` Christoph Hellwig
2018-11-15 19:51 ` [PATCH 06/11] block: have ->poll_fn() return number of entries polled Jens Axboe
2018-11-15 19:51 ` [PATCH 07/11] blk-mq: when polling for IO, look for any completion Jens Axboe
2018-11-16 8:43 ` Christoph Hellwig
2018-11-16 15:19 ` Jens Axboe
2018-11-16 16:57 ` Jens Axboe
2018-11-15 19:51 ` [PATCH 08/11] block: make blk_poll() take a parameter on whether to spin or not Jens Axboe
2018-11-15 19:51 ` [PATCH 09/11] blk-mq: ensure mq_ops ->poll() is entered at least once Jens Axboe
2018-11-15 19:51 ` [PATCH 10/11] block: for async O_DIRECT, mark us as polling if asked to Jens Axboe
2018-11-16 8:47 ` Christoph Hellwig
2018-11-16 8:48 ` Christoph Hellwig
2018-11-16 15:19 ` Jens Axboe
2018-11-15 19:51 ` [PATCH 11/11] block: don't plug for aio/O_DIRECT HIPRI IO Jens Axboe
2018-11-16 8:49 ` Christoph Hellwig
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