Re: [Xen-devel] [PATCH 18/19] libxl: suspend: Async evtchn wait

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2014-03-13 at 18:36 +0000, Ian Jackson wrote:
> Ian Campbell writes ("Re: [PATCH 18/19] libxl: suspend: Async evtchn wait"):
> > On Tue, 2014-03-04 at 14:56 +0000, Ian Jackson wrote:
> > > When negotiating guest suspend via the evtchn ("fast") protocol,
> > > abolish synchronous wait for domain suspend.
> >
> > [stuff]
> >
> > Neither of the above comments necessitate a change (although you could
> > clarify the commit message if you were so inclined):
> > Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> 
> Thanks.  Good idea.  Here's the new one.

Looks good, thanks.

Ian.

> 
> Ian.
> 
> libxl: suspend: Async evtchn wait
> 
> When negotiating guest suspend via the evtchn ("fast") protocol,
> abolish synchronous wait for domain suspend.
> 
> If the guest supports the event channel suspend protocol, we used to
> sit in a loop in xc_await_suspend waiting (perhaps indefinitely) for
> it to suspend.
> 
> Instead, use the new libxl event channel event facility.  When we see
> that the event is signaled, we look at the domain to see if it has
> suspended.  (In this patch we do not yet set a timeout; that will come
> next.)
> 
> So the suspend operation no longer blocks with the libxl ctx lock
> held, and instead returns to the event loop.  Additionally, domains
> which signal the event channel themselves, or undergo other state
> changes, will be handled more correctly.
> 
> We end up making a few more hypercalls.
> 
> Also, if we encounter errors setting up the suspend event channel
> (which should not happen), abort the operation rather than falling
> back to the xenstore protocol.
> 
> Signed-off-by: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
> CC: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> ---
> v4: Improve commit message.



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