Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754772Ab1BJLkT (ORCPT ); Thu, 10 Feb 2011 06:40:19 -0500 Received: from mtaout02-winn.ispmail.ntl.com ([81.103.221.48]:40628 "EHLO mtaout02-winn.ispmail.ntl.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751647Ab1BJLkR (ORCPT ); Thu, 10 Feb 2011 06:40:17 -0500 From: Ian Campbell To: Alan Stern Cc: Brendan Cully , "xen-devel@lists.xensource.com" , LKML , "Rafael J. Wysocki" , "linux-pm@lists.linux-foundation.org" , "SUZUKI, Kazuhiro" In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Date: Thu, 10 Feb 2011 11:40:05 +0000 Message-ID: <1297338005.20491.163.camel@zakaz.uk.xensource.com> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 62.200.22.2 X-SA-Exim-Mail-From: ijc@hellion.org.uk Subject: Re: [Xen-devel] Re: [linux-pm] [PATCH 0/2] Fix hangup after creating checkpoint on Xen. X-SA-Exim-Version: 4.2.1 (built Wed, 25 Jun 2008 17:14:11 +0000) X-SA-Exim-Scanned: Yes (on hopkins.hellion.org.uk) X-Cloudmark-Analysis: v=1.1 cv=JvdXmxIgLJv2/GthKqHpGJEEHukvLcvELVXUanXFreg= c=1 sm=0 a=wRiPVX2u-SEA:10 a=IkcTkHD0fZMA:10 a=svgH3AAeiMK6LjIMaxgA:9 a=hAIPPl5yHFH87OLcuY2wHPVeBecA:4 a=QEXdDO2ut3YA:10 a=HpAAvcLHHh0Zw7uRqdWCyQ==:117 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1998 Lines: 55 On Wed, 2011-02-09 at 23:42 +0000, Alan Stern wrote: > In fact there already is a "fast suspend & resume" path in the PM core. > It's the freeze/thaw procedure used when starting to hibernate. The > documentation specifically says that drivers' freeze methods are > supposed to quiesce their devices but not change power levels. In > addition, the thaw method is invoked as part of recovery from a failed > hibernation attempt, so it already has the "cancel" semantics that xen > seems to want. Sounds like that would work and I would much prefer to simply make correct use of the core functionality. So PMSG_FREEZE is balanced by either PMSG_RECOVER or PMSG_THAW depending on whether the suspend was cancelled or not? So the sequence of events is something like: dpm_suspend_start(PMSG_FREEZE); dpm_suspend_noirq(PMSG_FREEZE); sysdev_suspend(PMSG_QUIESCE); cancelled = suspend_hypercall() sysdev_resume(); dpm_resume_noirq(cancelled ? PMSG_RECOVER : PMSG_THAW); dpm_resume_end(cancelled ? PMSG_RECOVER : PMSG_THAW); ? (For comparison we currently have: > > > dpm_suspend_start(PMSG_SUSPEND); > > > > > > dpm_suspend_noirq(PMSG_SUSPEND); > > > > > > sysdev_suspend(PMSG_SUSPEND); > > > /* suspend hypercall */ > > > sysdev_resume(); > > > > > > dpm_resume_noirq(PMSG_RESUME); > > > > > > dpm_resume_end(PMSG_RESUME); ) Ian. -- Ian Campbell Current Noise: Neil Young - Angry World If only one could get that wonderful feeling of accomplishment without having to accomplish anything. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/