linux-kernel - Re: [PATCH v2 0/3] blk-mq: Optimise blk_mq_queue_tag_busy

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Message-ID: <67feacc8-3da7-90de-cc0c-f8b529f84297@kernel.dk>
Date:   Mon, 6 Dec 2021 12:07:00 -0700
From:   Jens Axboe <axboe@...nel.dk>
To:     John Garry <john.garry@...wei.com>
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        ming.lei@...hat.com, kashyap.desai@...adcom.com, hare@...e.de
Subject: Re: [PATCH v2 0/3] blk-mq: Optimise blk_mq_queue_tag_busy_iter() for
 shared tags

On 12/6/21 5:49 AM, John Garry wrote:
> In [0] Kashyap reports high CPU usage for blk_mq_queue_tag_busy_iter()
> and callees for shared tags.
> 
> Indeed blk_mq_queue_tag_busy_iter() would be less optimum for moving to
> shared tags, but it was not optimum previously.
> 
> This series optimises by having only a single iter (per regular and resv
> tags) for the shared tags, instead of an iter per HW queue.
> 
> [0] https://lore.kernel.org/linux-block/e4e92abbe9d52bcba6b8cc6c91c442cc@mail.gmail.com/

The patch(es) are missing Fixes tags.

-- 
Jens Axboe