From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH] nvme/pci: Use host managed power state for suspend Date: Mon, 13 May 2019 16:54:15 +0200 Message-ID: <20190513145415.GA25774@lst.de> References: <20190510212937.11661-1-keith.busch@intel.com> <0080aaff18e5445dabca509d4113eca8@AUSX13MPC105.AMER.DELL.COM> <955722d8fc16425dbba0698c4806f8fd@AUSX13MPC105.AMER.DELL.COM> <20190513143741.GA25500@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Mario.Limonciello@dell.com Cc: hch@lst.de, keith.busch@intel.com, sagi@grimberg.me, linux-nvme@lists.infradead.org, rafael@kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, kai.heng.feng@canonical.com List-Id: linux-pm@vger.kernel.org On Mon, May 13, 2019 at 02:43:43PM +0000, Mario.Limonciello@dell.com wrote: > Well I've got a thought, quoting the NVME spec: > "After a successful completion of a Set Features command for this feature, the controller shall be in the > Power State specified. If enabled, autonomous power state transitions continue to occur from the new state." > > If APST is enabled on this disk, what is to stop an autonomous reverse > transition from queue activity on the way down? Nothing. But once the system is suspending we should not see I/O. If we see I/O the queue freezing in the original patch Kai Heng and the previous one from Keith is probably required, although I suspect it just papers over problems higher up in the queue. If we don't see I/O the device is just behaving oddly. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5CC09C04AA7 for ; Mon, 13 May 2019 14:54:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3769420645 for ; Mon, 13 May 2019 14:54:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730696AbfEMOyh (ORCPT ); Mon, 13 May 2019 10:54:37 -0400 Received: from verein.lst.de ([213.95.11.211]:39796 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729772AbfEMOyh (ORCPT ); Mon, 13 May 2019 10:54:37 -0400 Received: by newverein.lst.de (Postfix, from userid 2407) id 7B72E68AFE; Mon, 13 May 2019 16:54:15 +0200 (CEST) Date: Mon, 13 May 2019 16:54:15 +0200 From: Christoph Hellwig To: Mario.Limonciello@dell.com Cc: hch@lst.de, keith.busch@intel.com, sagi@grimberg.me, linux-nvme@lists.infradead.org, rafael@kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, kai.heng.feng@canonical.com Subject: Re: [PATCH] nvme/pci: Use host managed power state for suspend Message-ID: <20190513145415.GA25774@lst.de> References: <20190510212937.11661-1-keith.busch@intel.com> <0080aaff18e5445dabca509d4113eca8@AUSX13MPC105.AMER.DELL.COM> <955722d8fc16425dbba0698c4806f8fd@AUSX13MPC105.AMER.DELL.COM> <20190513143741.GA25500@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Message-ID: <20190513145415.LX4NrKRM1LC2inS5ysmg4xlpq9uyIYqvNUCo0dj7fJg@z> On Mon, May 13, 2019 at 02:43:43PM +0000, Mario.Limonciello@dell.com wrote: > Well I've got a thought, quoting the NVME spec: > "After a successful completion of a Set Features command for this feature, the controller shall be in the > Power State specified. If enabled, autonomous power state transitions continue to occur from the new state." > > If APST is enabled on this disk, what is to stop an autonomous reverse > transition from queue activity on the way down? Nothing. But once the system is suspending we should not see I/O. If we see I/O the queue freezing in the original patch Kai Heng and the previous one from Keith is probably required, although I suspect it just papers over problems higher up in the queue. If we don't see I/O the device is just behaving oddly.