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From: Jens Axboe <axboe@kernel.dk>
To: Ming Lei <ming.lei@redhat.com>
Cc: linux-block@vger.kernel.org, Sagi Grimberg <sagi@grimberg.me>,
	Baolin Wang <baolin.wang7@gmail.com>,
	Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH V7 0/6] blk-mq: support batching dispatch from scheduler
Date: Tue, 30 Jun 2020 08:03:01 -0600
Message-ID: <6dc23dec-aad3-b2a3-3e11-71c186ddbc0b@kernel.dk> (raw)
In-Reply-To: <20200630102501.2238972-1-ming.lei@redhat.com>

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]

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