Re: [PATCH v1 0/3] Asynchronous shutdown interface and example implementation

From: Lukas Wunner <lukas@wunner.de>
To: Keith Busch <kbusch@kernel.org>
Cc: Tanjore Suresh <tansuresh@google.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
	Bjorn Helgaas <bhelgaas@google.com>,
	linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
	linux-pci@vger.kernel.org
Subject: Re: [PATCH v1 0/3] Asynchronous shutdown interface and example implementation
Date: Wed, 30 Mar 2022 08:25:16 +0200	[thread overview]
Message-ID: <20220330062516.GA24340@wunner.de> (raw)
In-Reply-To: <YkO7d7Eel4BVQOy4@kbusch-mbp.dhcp.thefacebook.com>

On Tue, Mar 29, 2022 at 08:07:51PM -0600, Keith Busch wrote:
> Thanks, I agree we should improve shutdown times. I tried a while ago, but
> lost track to follow up at the time. Here's the reference, fwiw, though it
> may be out of date :):
> 
>   http://lists.infradead.org/pipermail/linux-nvme/2014-May/000826.html
> 
> The above solution is similiar to how probe waits on an async domain.
> Maybe pci can schedule the async shutdown instead of relying on low-level
> drivers so that everyone implicitly benefits instead of just nvme? I'll
> double-check if that's reasonable, but I'll look through this series too.

Using the async API seems much more reasonable than adding new callbacks.

However I'd argue that it shouldn't be necessary to amend any drivers,
this should all be doable in the driver core:  Basically a device needs
to wait for its children and device links consumers to shutdown, apart
from that everything should be able to run asynchronously.

Thanks,

Lukas