xen-devel
Re: [Xen-devel] Re: [linux-pm] [PATCH 0/2] Fix hangup after creating che
To: |
Ian Campbell <ijc@xxxxxxxxxxxxxx> |
Subject: |
Re: [Xen-devel] Re: [linux-pm] [PATCH 0/2] Fix hangup after creating checkpoint on Xen. |
From: |
Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> |
Date: |
Thu, 10 Feb 2011 11:00:51 -0500 (EST) |
Cc: |
"xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, LKML <linux-kernel@xxxxxxxxxxxxxxx>, "Rafael J. Wysocki" <rjw@xxxxxxx>, Brendan Cully <brendan@xxxxxxxxx>, "linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx" <linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx>, "SUZUKI, Kazuhiro" <kaz@xxxxxxxxxxxxxx> |
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On Thu, 10 Feb 2011, Ian Campbell wrote:
> 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.
It seems like a reasonable approach. Whether it will actually _work_
is a harder question... :-)
> So PMSG_FREEZE is balanced by either PMSG_RECOVER or PMSG_THAW depending
> on whether the suspend was cancelled or not?
Basically yes. It is also "balanced" by PMSG_RESTORE, which is used
after a memory image has been restored (although this isn't relevant to
your snapshotting). See the comments in include/linux/pm.h.
> So the sequence of events
> is something like:
> dpm_suspend_start(PMSG_FREEZE);
>
> dpm_suspend_noirq(PMSG_FREEZE);
>
> sysdev_suspend(PMSG_QUIESCE);
This should say sysdev_suspend(PMSG_FREEZE).
> cancelled = suspend_hypercall()
At this point swsusp_arch_suspend() is called. If that translates to
suspend_hypercall() in your setting, then yes.
> sysdev_resume();
>
> dpm_resume_noirq(cancelled ? PMSG_RECOVER : PMSG_THAW);
>
> dpm_resume_end(cancelled ? PMSG_RECOVER : PMSG_THAW);
> ?
Yes.
> (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);
> )
Right. The sequence of calls is the same, but the PMSG_ argument is
different so drivers are expected to act differently in response.
Alan Stern
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- [Xen-devel] [PATCH 0/2] Fix hangup after creating checkpoint on Xen., SUZUKI, Kazuhiro
- [Xen-devel] [PATCH 1/2] Fix hangup after creating checkpoint on Xen., SUZUKI, Kazuhiro
- [Xen-devel] [PATCH 2/2] Fix hangup after creating checkpoint on Xen., SUZUKI, Kazuhiro
- [Xen-devel] Re: [PATCH 0/2] Fix hangup after creating checkpoint on Xen., Rafael J. Wysocki
- [Xen-devel] Re: [PATCH 0/2] Fix hangup after creating checkpoint on Xen., Ian Campbell
- [Xen-devel] Re: [linux-pm] [PATCH 0/2] Fix hangup after creating checkpoint on Xen., Alan Stern
- [Xen-devel] Re: [linux-pm] [PATCH 0/2] Fix hangup after creating checkpoint on Xen., Ian Campbell
- [Xen-devel] Re: [linux-pm] [PATCH 0/2] Fix hangup after creating checkpoint on Xen., Brendan Cully
- [Xen-devel] Re: [linux-pm] [PATCH 0/2] Fix hangup after creating checkpoint on Xen., Alan Stern
- Re: [Xen-devel] Re: [linux-pm] [PATCH 0/2] Fix hangup after creating checkpoint on Xen., Ian Campbell
- Re: [Xen-devel] Re: [linux-pm] [PATCH 0/2] Fix hangup after creating checkpoint on Xen.,
Alan Stern <=
- Re: [Xen-devel] Re: [linux-pm] [PATCH 0/2] Fix hangup after creating checkpoint on Xen., Rafael J. Wysocki
- Re: [Xen-devel] Re: [linux-pm] [PATCH 0/2] Fix hangup after creating checkpoint on Xen., Ian Campbell
- Re: [Xen-devel] Re: [linux-pm] [PATCH 0/2] Fix hangup after creating checkpoint on Xen., Rafael J. Wysocki
- [Xen-devel] [PATCH] update comments in pm.h describing Xen Guest save/restore/checkpoint use case, Shriram Rajagopalan
- Re: [Xen-devel] [PATCH] update comments in pm.h describing Xen Guest save/restore/checkpoint use case, Ian Campbell
- Re: [Xen-devel] Re: [linux-pm] [PATCH 0/2] Fix hangup after creating checkpoint on Xen., Alan Stern
- Re: [Xen-devel] Re: [linux-pm] [PATCH 0/2] Fix hangup after creating checkpoint on Xen., Ian Campbell
- Re: [Xen-devel] Re: [linux-pm] [PATCH 0/2] Fix hangup after creating checkpoint on Xen., Ian Campbell
- Re: [Xen-devel] Re: [linux-pm] [PATCH 0/2] Fix hangup after creating checkpoint on Xen., Brendan Cully
- Re: [Xen-devel] Re: [linux-pm] [PATCH 0/2] Fix hangup after creating checkpoint on Xen., Ian Campbell
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