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From: Jens Axboe <axboe@kernel.dk>
To: John Garry <john.garry@huawei.com>
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	ming.lei@redhat.com, hare@suse.de, linux-scsi@vger.kernel.org,
	kashyap.desai@broadcom.com
Subject: Re: [PATCH v5 00/14] blk-mq: Reduce static requests memory footprint for shared sbitmap
Date: Tue, 5 Oct 2021 06:35:52 -0600	[thread overview]
Message-ID: <ae33dde8-96e8-2978-5f32-c7e0a6136e8e@kernel.dk> (raw)
In-Reply-To: <1633429419-228500-1-git-send-email-john.garry@huawei.com>

On 10/5/21 4:23 AM, John Garry wrote:
> Currently a full set of static requests are allocated per hw queue per
> tagset when shared sbitmap is used.
> 
> However, only tagset->queue_depth number of requests may be active at
> any given time. As such, only tagset->queue_depth number of static
> requests are required.
> 
> The same goes for using an IO scheduler, which allocates a full set of
> static requests per hw queue per request queue.
> 
> This series changes shared sbitmap support by using a shared tags per
> tagset and request queue. Ming suggested something along those lines in
> v1 review. In using a shared tags, the static rqs also become shared,
> reducing the number of sets of static rqs, reducing memory usage.
> 
> Patch "blk-mq: Use shared tags for shared sbitmap support" is a bit big,
> and could potentially be broken down. But then maintaining ability to
> bisect becomes harder and each sub-patch would get more convoluted.
> 
> For megaraid sas driver on my 128-CPU arm64 system with 1x SATA disk, we
> save approx. 300MB(!) [370MB -> 60MB]
> 
> Baseline is 1b2d1439fc25 (block/for-next) Merge branch 'for-5.16/io_uring'
> into for-next

Let's get this queued up for testing, thanks John.

-- 
Jens Axboe


  parent reply	other threads:[~2021-10-05 12:37 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-05 10:23 [PATCH v5 00/14] blk-mq: Reduce static requests memory footprint for shared sbitmap John Garry
2021-10-05 10:23 ` [PATCH v5 01/14] blk-mq: Change rqs check in blk_mq_free_rqs() John Garry
2021-10-05 10:23 ` [PATCH v5 02/14] block: Rename BLKDEV_MAX_RQ -> BLKDEV_DEFAULT_RQ John Garry
2021-10-05 10:23 ` [PATCH v5 03/14] blk-mq: Relocate shared sbitmap resize in blk_mq_update_nr_requests() John Garry
2021-10-05 10:23 ` [PATCH v5 04/14] blk-mq: Invert check " John Garry
2021-10-05 10:23 ` [PATCH v5 05/14] blk-mq-sched: Rename blk_mq_sched_alloc_{tags -> map_and_rqs}() John Garry
2021-10-05 10:23 ` [PATCH v5 06/14] blk-mq-sched: Rename blk_mq_sched_free_{requests -> rqs}() John Garry
2021-10-05 10:23 ` [PATCH v5 07/14] blk-mq: Pass driver tags to blk_mq_clear_rq_mapping() John Garry
2021-10-05 10:23 ` [PATCH v5 08/14] blk-mq: Don't clear driver tags own mapping John Garry
2021-10-05 10:23 ` [PATCH v5 09/14] blk-mq: Add blk_mq_tag_update_sched_shared_sbitmap() John Garry
2021-10-05 10:23 ` [PATCH v5 10/14] blk-mq: Add blk_mq_alloc_map_and_rqs() John Garry
2021-10-05 10:23 ` [PATCH v5 11/14] blk-mq: Refactor and rename blk_mq_free_map_and_{requests->rqs}() John Garry
2021-10-05 10:23 ` [PATCH v5 12/14] blk-mq: Use shared tags for shared sbitmap support John Garry
2021-10-05 10:23 ` [PATCH v5 13/14] blk-mq: Stop using pointers for blk_mq_tags bitmap tags John Garry
2021-10-05 10:23 ` [PATCH v5 14/14] blk-mq: Change shared sbitmap naming to shared tags John Garry
2021-10-05 12:35 ` Jens Axboe [this message]
2021-10-05 13:34   ` [PATCH v5 00/14] blk-mq: Reduce static requests memory footprint for shared sbitmap John Garry
2021-10-05 13:53     ` Kashyap Desai
2021-10-05 16:23     ` Jens Axboe
2021-10-07 20:31     ` Kashyap Desai
2021-10-08  3:11       ` Bart Van Assche
2021-10-08  8:07         ` John Garry
2021-10-08 10:17       ` John Garry

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