linux-kernel - Re: [PATCH] nvme/pci: Use host managed power state for suspend

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Date:   Mon, 13 May 2019 09:04:58 -0600
From:   Keith Busch <kbusch@...nel.org>
To:     Mario.Limonciello@...l.com
Cc:     hch@....de, keith.busch@...el.com, sagi@...mberg.me,
        linux-nvme@...ts.infradead.org, rafael@...nel.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        kai.heng.feng@...onical.com
Subject: Re: [PATCH] nvme/pci: Use host managed power state for suspend

On Mon, May 13, 2019 at 03:05:42PM +0000, Mario.Limonciello@...l.com wrote:
> This system power state - suspend to idle is going to freeze threads.
> But we're talking a multi threaded kernel.  Can't there be a timing problem going
> on then too?  With a disk flush being active in one task and the other task trying
> to put the disk into the deepest power state.  If you don't freeze the queues how
> can you guarantee that didn't happen?

But if an active data flush task is running, then we're not idle and
shouldn't go to low power.