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Date: Wed, 27 May 2026 21:03:02 -0600
From: Keith Busch <kbusch@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: guzebing <guzebing1612@gmail.com>, axboe@kernel.dk, sagi@grimberg.me,
	linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
	Guzebing <guzebing@bytedance.com>
Subject: Re: [RFC PATCH 0/1] nvme-pci: detect I/O queue depth changes after
 reset
Message-ID: <ahewZiV3n6qG1Jhm@kbusch-mbp>
References: <20260527075320.3178600-1-guzebing1612@gmail.com>
 <20260527131951.GA11071@lst.de>
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In-Reply-To: <20260527131951.GA11071@lst.de>

On Wed, May 27, 2026 at 03:19:51PM +0200, Christoph Hellwig wrote:
> On Wed, May 27, 2026 at 03:53:19PM +0800, guzebing wrote:
> > This RFC instead takes the smaller approach of detecting the reset-time
> > CAP.MQES change and making it visible.  If the live I/O queue depth
> > shrinks, reset recovery is failed before recreating I/O queues.  If it
> > grows, the driver warns and continues with the existing queue resources.
> 
> Unlike the other version this at least sounds doable without creating
> a complete mess.  So if we can live with this version that'd make me
> much happier.

Abandoning the device here sounds pretty harsh when blk-mq already
supports user space decreasing the q-depth on a live queue. Why can't
the driver do the same thing?