Linux-Block Archive on
 help / color / Atom feed
From: Jens Axboe <>
To: Ming Lei <>
Cc:, Sagi Grimberg <>,
	Baolin Wang <>,
	Christoph Hellwig <>
Subject: Re: [PATCH V7 0/6] blk-mq: support batching dispatch from scheduler
Date: Tue, 30 Jun 2020 08:03:01 -0600
Message-ID: <> (raw)
In-Reply-To: <>

On 6/30/20 4:24 AM, Ming Lei wrote:
> Hi Jens,
> More and more drivers want to get batching requests queued from
> block layer, such as mmc[1], and tcp based storage drivers[2]. Also
> current in-tree users have virtio-scsi, virtio-blk and nvme.
> For none, we already support batching dispatch.
> But for io scheduler, every time we just take one request from scheduler
> and pass the single request to blk_mq_dispatch_rq_list(). This way makes
> batching dispatch not possible when io scheduler is applied. One reason
> is that we don't want to hurt sequential IO performance, becasue IO
> merge chance is reduced if more requests are dequeued from scheduler
> queue.
> Tries to start the support by dequeuing more requests from scheduler
> if budget is enough and device isn't busy.
> Simple fio test over virtio-scsi shows IO can get improved by 5~10%.
> Baolin has tested previous versions and found performance on MMC can be improved.
> Patch 1 ~ 4 are improvement and cleanup, which can't applied without
> supporting batching dispatch.
> Patch 5 ~ 6 starts to support batching dispatch from scheduler.

Thanks Ming, applied for 5.9.

Jens Axboe

      parent reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-30 10:24 Ming Lei
2020-06-30 10:24 ` [PATCH V7 1/6] blk-mq: pass request queue into get/put budget callback Ming Lei
2020-06-30 10:24 ` [PATCH V7 2/6] blk-mq: pass hctx to blk_mq_dispatch_rq_list Ming Lei
2020-06-30 10:24 ` [PATCH V7 3/6] blk-mq: move getting driver tag and budget into one helper Ming Lei
2020-06-30 10:24 ` [PATCH V7 4/6] blk-mq: remove dead check from blk_mq_dispatch_rq_list Ming Lei
2020-06-30 10:25 ` [PATCH V7 5/6] blk-mq: pass obtained budget count to blk_mq_dispatch_rq_list Ming Lei
2020-06-30 10:25 ` [PATCH V7 6/6] blk-mq: support batching dispatch in case of io Ming Lei
2020-06-30 13:40   ` Christoph Hellwig
2020-06-30 14:03 ` Jens Axboe [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Block Archive on

Archives are clonable:
	git clone --mirror linux-block/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-block linux-block/ \
	public-inbox-index linux-block

Example config snippet for mirrors

Newsgroup available over NNTP:

AGPL code for this site: git clone