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Date: Tue, 29 Oct 2024 16:32:39 +0100
From: Christoph Hellwig <hch@lst.de>
To: Michael Kelley <mhklinux@outlook.com>
Cc: stuart hayes <stuart.w.hayes@gmail.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Lukas Wunner <lukas@wunner.de>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	Martin Belanger <Martin.Belanger@dell.com>,
	Oliver O'Halloran <oohall@gmail.com>,
	Daniel Wagner <dwagner@suse.de>, Keith Busch <kbusch@kernel.org>,
	David Jeffery <djeffery@redhat.com>,
	Jeremy Allison <jallison@ciq.com>, Jens Axboe <axboe@fb.com>,
	Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
	"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
	Nathan Chancellor <nathan@kernel.org>,
	Jan Kiszka <jan.kiszka@seimens.com>,
	Bert Karwatzki <spasswolf@web.de>
Subject: Re: [PATCH v9 0/4] shut down devices asynchronously
Message-ID: <20241029153238.GA26979@lst.de>
References: <20241009175746.46758-1-stuart.w.hayes@gmail.com> <BN7PR02MB41480DE777B9C224F3C2DF43D4792@BN7PR02MB4148.namprd02.prod.outlook.com> <SN6PR02MB41571E2DD410D09CE7494B38D4402@SN6PR02MB4157.namprd02.prod.outlook.com> <2024101809-granola-coat-9a1d@gregkh> <ZxInC1U7WiB7FNkJ@wunner.de> <2024101808-subscribe-unwrapped-ee3d@gregkh> <7ec51cc8-b64f-4956-b4e6-4b67f1a8fa76@gmail.com> <SN6PR02MB4157B4916F2B8581B9C6E214D4422@SN6PR02MB4157.namprd02.prod.outlook.com>
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On Sun, Oct 20, 2024 at 12:24:32AM +0000, Michael Kelley wrote:
> Yes, I agree that a single core system should be able to get multiple
> NVMe drives shutting down in parallel. The parallelism would be
> governed by the number of worker processes that the workqueue
> decides are needed. I didn't look at how it makes that decision.

Or we could just go back to the old design where one methods kicks off
the shutdown, and then another one waits for it, which requires no
extra threads at all.