linux-kernel - Re: [PATCH v2 1/2] nvme: Add Arbitration Burst support

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Message-ID: <20200624065258.GA18130@lst.de>
Date:   Wed, 24 Jun 2020 08:52:58 +0200
From:   Christoph Hellwig <hch@....de>
To:     Baolin Wang <baolin.wang@...ux.alibaba.com>
Cc:     kbusch@...nel.org, axboe@...com, hch@....de, sagi@...mberg.me,
        baolin.wang7@...il.com, linux-nvme@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] nvme: Add Arbitration Burst support

On Wed, Jun 24, 2020 at 02:49:57PM +0800, Baolin Wang wrote:
> >From the NVMe spec, "In order to make efficient use of the non-volatile
> memory, it is often advantageous to execute multiple commands from a
> Submission Queue in parallel. For Submission Queues that are using
> weighted round robin with urgent priority class or round robin
> arbitration, host software may configure an Arbitration Burst setting".
> Thus add Arbitration Burst setting support.

What is the value add of doing this in the kernel?  Wouldn't a nvme-cli
subcommand to just set the arbitration burst to the recommended value,
either as a saved or current value be both more useful and also cause
less kernel bloat?