From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keith Busch <keith.busch@intel.com>
Subject: Re: [PATCH] nvme: Acknowledge completion queue on each iteration
Date: Mon, 17 Jul 2017 18:45:51 -0400
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To: Sinan Kaya <okaya@codeaurora.org>
Cc: linux-nvme@lists.infradead.org, timur@codeaurora.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Jens Axboe <axboe@fb.com>, Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>, linux-kernel@vger.kernel.org

On Mon, Jul 17, 2017 at 06:36:23PM -0400, Sinan Kaya wrote:
> Code is moving the completion queue doorbell after processing all completed
> events and sending callbacks to the block layer on each iteration.
> 
> This is causing a performance drop when a lot of jobs are queued towards
> the HW. Move the completion queue doorbell on each loop instead and allow new
> jobs to be queued by the HW.

That doesn't make sense. Aggregating doorbell writes should be much more
efficient for high depth workloads.