From: Damien Le Moal <dlemoal@kernel.org>
To: Bart Van Assche <bvanassche@acm.org>, Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, linux-scsi@vger.kernel.org,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v18 02/12] block: Rework request allocation in blk_mq_submit_bio()
Date: Thu, 26 Jun 2025 09:00:49 +0900 [thread overview]
Message-ID: <aeeb5b64-e539-4f0b-b80e-5aaecde55550@kernel.org> (raw)
In-Reply-To: <20250616223312.1607638-3-bvanassche@acm.org>
On 6/17/25 07:33, Bart Van Assche wrote:
> Prepare for allocating a request from a specific hctx by making
> blk_mq_submit_bio() allocate a request later.
>
> The performance impact of this patch on the hot path is small: if a
> request is cached, one percpu_ref_get(&q->q_usage_counter) call and one
> percpu_ref_put(&q->q_usage_counter) call are added to the hot path.
Numbers ?
The change is forcing a queue enter for all BIOs because you remove the cached
request optimization. So I am not sure it is the impact is that small if you
have a very fast storage device.
--
Damien Le Moal
Western Digital Research
next prev parent reply other threads:[~2025-06-26 0:00 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-16 22:33 [PATCH v18 00/12] Improve write performance for zoned UFS devices Bart Van Assche
2025-06-16 22:33 ` [PATCH v18 01/12] block: Support block drivers that preserve the order of write requests Bart Van Assche
2025-06-16 22:33 ` [PATCH v18 02/12] block: Rework request allocation in blk_mq_submit_bio() Bart Van Assche
2025-06-26 0:00 ` Damien Le Moal [this message]
2025-06-26 17:25 ` Bart Van Assche
2025-06-16 22:33 ` [PATCH v18 03/12] block: Support allocating from a specific software queue Bart Van Assche
2025-06-26 0:04 ` Damien Le Moal
2025-06-26 17:17 ` Bart Van Assche
2025-06-16 22:33 ` [PATCH v18 04/12] blk-mq: Restore the zoned write order when requeuing Bart Van Assche
2025-06-26 0:11 ` Damien Le Moal
2025-06-26 19:42 ` Bart Van Assche
2025-06-16 22:33 ` [PATCH v18 05/12] blk-zoned: Add an argument to blk_zone_plug_bio() Bart Van Assche
2025-06-17 12:49 ` kernel test robot
2025-06-26 0:15 ` Damien Le Moal
2025-06-26 17:16 ` Bart Van Assche
2025-06-16 22:33 ` [PATCH v18 06/12] blk-zoned: Support pipelining of zoned writes Bart Van Assche
2025-06-16 22:33 ` [PATCH v18 07/12] null_blk: Add the preserves_write_order attribute Bart Van Assche
2025-06-16 22:33 ` [PATCH v18 08/12] scsi: core: Retry unaligned zoned writes Bart Van Assche
2025-06-16 22:33 ` [PATCH v18 09/12] scsi: sd: Increase retry count for " Bart Van Assche
2025-06-16 22:33 ` [PATCH v18 10/12] scsi: scsi_debug: Add the preserves_write_order module parameter Bart Van Assche
2025-06-16 22:33 ` [PATCH v18 11/12] scsi: scsi_debug: Support injecting unaligned write errors Bart Van Assche
2025-06-16 22:33 ` [PATCH v18 12/12] scsi: ufs: Inform the block layer about write ordering Bart Van Assche
2025-06-17 6:58 ` Avri Altman
2025-06-19 12:49 ` Peter Wang (王信友)
2025-06-19 16:38 ` Bart Van Assche
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