Messages in this thread | | | From | Ian Campbell <> | Date | Thu, 10 Feb 2011 11:40:05 +0000 | Subject | Re: [Xen-devel] Re: [linux-pm] [PATCH 0/2] Fix hangup after creating checkpoint on Xen. |
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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.
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