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From: Bart Van Assche <bvanassche@acm.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, linux-scsi@vger.kernel.org,
	linux-fsdevel@vger.kernel.org,
	"Martin K . Petersen" <martin.petersen@oracle.com>,
	Christoph Hellwig <hch@lst.de>,
	Niklas Cassel <Niklas.Cassel@wdc.com>,
	Avri Altman <Avri.Altman@wdc.com>, Bean Huo <huobean@gmail.com>,
	Daejun Park <daejun7.park@samsung.com>
Subject: Re: [PATCH v3 00/14] Pass data temperature information to SCSI disk devices
Date: Fri, 20 Oct 2023 13:45:40 -0700	[thread overview]
Message-ID: <42639844-8758-4396-bb2c-ffcc8593d205@acm.org> (raw)
In-Reply-To: <3f3c2289-3185-4895-92cb-0692e3ca9ebc@kernel.dk>

On 10/18/23 12:09, Jens Axboe wrote:
> I'm also really against growing struct bio just for this. Why is patch 2
> not just using the ioprio field at least?

Hi Jens,

Can you please clarify whether your concern is about the size of struct 
bio only or also about the runtime impact of the comparisons that have 
been added in attempt_merge() and blk_rq_merge_ok()? It may be possible 
to eliminate the overhead of the new comparisons as follows:
* Introduce a union of struct { I/O priority; data lifetime; } and u32.
* Use that union in struct bio instead of bi_ioprio and bi_lifetime.
* Use that union in struct request instead of the ioprio and lifetime
   members.
* In attempt_merge() and blk_rq_merge_ok(), compare the u32 union member
   instead of comparing the I/O priority and data lifetime separately.

Thanks,

Bart.

      parent reply	other threads:[~2023-10-20 20:46 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-10-17 20:47 [PATCH v3 00/14] Pass data temperature information to SCSI disk devices Bart Van Assche
2023-10-17 20:47 ` [PATCH v3 01/14] fs: Move enum rw_hint into a new header file Bart Van Assche
2023-10-30 11:11   ` Kanchan Joshi
2023-10-30 16:10     ` Bart Van Assche
2023-11-01  6:39       ` Daejun Park
2023-11-01 16:45         ` (2) " Bart Van Assche
2023-11-02  7:31           ` Daejun Park
2023-10-17 20:47 ` [PATCH v3 02/14] block: Restore data lifetime support in struct bio and struct request Bart Van Assche
2023-10-17 20:47 ` [PATCH v3 03/14] fs: Restore write hint support Bart Van Assche
2023-10-17 20:47 ` [PATCH v3 04/14] fs/f2fs: Restore data lifetime support Bart Van Assche
2023-10-17 20:47 ` [PATCH v3 05/14] scsi: core: Query the Block Limits Extension VPD page Bart Van Assche
2023-10-17 20:47 ` [PATCH v3 06/14] scsi_proto: Add structures and constants related to I/O groups and streams Bart Van Assche
2023-10-17 20:47 ` [PATCH v3 07/14] sd: Translate data lifetime information Bart Van Assche
2023-10-17 20:47 ` [PATCH v3 08/14] scsi_debug: Reduce code duplication Bart Van Assche
2023-10-17 20:47 ` [PATCH v3 09/14] scsi_debug: Support the block limits extension VPD page Bart Van Assche
2023-10-17 20:47 ` [PATCH v3 10/14] scsi_debug: Rework page code error handling Bart Van Assche
2023-10-17 20:47 ` [PATCH v3 11/14] scsi_debug: Rework subpage " Bart Van Assche
2023-10-17 20:47 ` [PATCH v3 12/14] scsi_debug: Implement the IO Advice Hints Grouping mode page Bart Van Assche
2023-10-17 20:47 ` [PATCH v3 13/14] scsi_debug: Implement GET STREAM STATUS Bart Van Assche
2023-10-17 20:47 ` [PATCH v3 14/14] scsi_debug: Maintain write statistics per group number Bart Van Assche
2023-10-18 19:09 ` [PATCH v3 00/14] Pass data temperature information to SCSI disk devices Jens Axboe
2023-10-18 19:34   ` Bart Van Assche
2023-10-19  0:33     ` Damien Le Moal
2023-10-19 16:48       ` Bart Van Assche
2023-10-19 22:40         ` Damien Le Moal
2023-10-19 23:00           ` Damien Le Moal
2023-10-20 20:45   ` Bart Van Assche [this message]

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