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Date:   Thu, 5 Oct 2023 11:36:21 +0200
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Stuart Hayes <stuart.w.hayes@gmail.com>
Cc:     linux-kernel@vger.kernel.org,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        Tanjore Suresh <tansuresh@google.com>,
        Martin Belanger <Martin.Belanger@dell.com>,
        Oliver O'Halloran <oohall@gmail.com>,
        Daniel Wagner <dwagner@suse.de>,
        Keith Busch <kbusch@kernel.org>, Lukas Wunner <lukas@wunner.de>
Subject: Re: [PATCH v4] driver core: shut down devices asynchronously
Message-ID: <2023100507-refocus-stooge-08dd@gregkh>
References: <20230921163443.9224-1-stuart.w.hayes@gmail.com>
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In-Reply-To: <20230921163443.9224-1-stuart.w.hayes@gmail.com>
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On Thu, Sep 21, 2023 at 11:34:43AM -0500, Stuart Hayes wrote:
> Shut down devices asynchronously, ensuring that each device is shut down
> before its parents.
> 
> This can dramatically reduce system shutdown/reboot time on systems that
> have devices that take many seconds to shut down, such as some NVMe drives.
> On one system tested, the shutdown time went from 11 minutes without this
> patch to 55 seconds with the patch.

That's a nice improvement, but I think we need a lot more testing on a
wide range of systems before we can take a patch like this.

Also, what about busses that don't want this type of shutdown?  We allow
busses to opt-in for async probing, shouldn't that be also done for
shutting them down to resolve issues for busses that can not handle
this?

thanks,

greg k-h