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From: Jens Axboe <axboe@kernel.dk>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-block@vger.kernel.org
Subject: Re: [PATCH 01/14] block: inline fast path of driver tag allocation
Date: Mon, 18 Oct 2021 08:38:22 -0600	[thread overview]
Message-ID: <994eb1b3-90d0-0980-5c2a-46937d4d5a62@kernel.dk> (raw)
In-Reply-To: <YW0zXEOcn/lkozM5@infradead.org>

On 10/18/21 2:42 AM, Christoph Hellwig wrote:
> On Sat, Oct 16, 2021 at 07:37:35PM -0600, Jens Axboe wrote:
>> If we don't use an IO scheduler or have shared tags, then we don't need
>> to call into this external function at all. This saves ~2% for such
>> a setup.
> 
> This looks correct, although the call chain gets a little confusing
> now.  How much difference is this over basically inlining the
> whole old blk_mq_get_driver_tag?

It just condenses the fast path into the checks upfront. I can run the
numbers, but it'll be extra work.

-- 
Jens Axboe


  reply	other threads:[~2021-10-18 14:38 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-17  1:37 [PATCHSET 0/14] Various block layer optimizations Jens Axboe
2021-10-17  1:37 ` [PATCH 01/14] block: inline fast path of driver tag allocation Jens Axboe
2021-10-18  8:42   ` Christoph Hellwig
2021-10-18 14:38     ` Jens Axboe [this message]
2021-10-17  1:37 ` [PATCH 02/14] block: don't bother iter advancing a fully done bio Jens Axboe
2021-10-18  8:42   ` Christoph Hellwig
2021-10-17  1:37 ` [PATCH 03/14] block: remove useless caller argument to print_req_error() Jens Axboe
2021-10-18  8:42   ` Christoph Hellwig
2021-10-17  1:37 ` [PATCH 04/14] block: move update request helpers into blk-mq.c Jens Axboe
2021-10-18  8:43   ` Christoph Hellwig
2021-10-17  1:37 ` [PATCH 05/14] block: don't call blk_status_to_errno() for success status Jens Axboe
2021-10-18  8:53   ` Christoph Hellwig
2021-10-18 10:49   ` Pavel Begunkov
2021-10-17  1:37 ` [PATCH 06/14] block: store elevator state in request Jens Axboe
2021-10-18  8:58   ` Christoph Hellwig
2021-10-18 14:34     ` Jens Axboe
2021-10-19 22:21   ` Guillaume Tucker
2021-10-19 22:26     ` Jens Axboe
2021-10-17  1:37 ` [PATCH 07/14] block: change plugging to use a singly linked list Jens Axboe
2021-10-17  4:45   ` kernel test robot
2021-10-17  4:45     ` kernel test robot
2021-10-18  9:19   ` Christoph Hellwig
2021-10-18 16:10     ` Jens Axboe
2021-10-18 12:56   ` Pavel Begunkov
2021-10-18 13:34     ` Jens Axboe
2021-10-24 14:09   ` kernel test robot
2021-10-17  1:37 ` [PATCH 08/14] block: improve layout of struct request Jens Axboe
2021-10-18  9:19   ` Christoph Hellwig
2021-10-17  1:37 ` [PATCH 09/14] block: only mark bio as tracked if it really is tracked Jens Axboe
2021-10-18  9:19   ` Christoph Hellwig
2021-10-17  1:37 ` [PATCH 10/14] block: move blk_mq_tag_to_rq() inline Jens Axboe
2021-10-17  1:37 ` [PATCH 11/14] block: optimize blk_mq_rq_ctx_init() Jens Axboe
2021-10-18  9:20   ` Christoph Hellwig
2021-10-17  1:37 ` [PATCH 12/14] block: align blkdev_dio inlined bio to a cacheline Jens Axboe
2021-10-18  9:21   ` Christoph Hellwig
2021-10-18 14:36     ` Jens Axboe
2021-10-17  1:37 ` [PATCH 13/14] block: remove debugfs blk_mq_ctx dispatched/merged/completed attributes Jens Axboe
2021-10-18  9:21   ` Christoph Hellwig
2021-10-17  1:37 ` [PATCH 14/14] block: remove some blk_mq_hw_ctx debugfs entries Jens Axboe
2021-10-18  9:22   ` Christoph Hellwig

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