Re: [Xen-devel] [PATCH] xen: release lock occasionally during ballooning

[Juergen Gross <jgross@xxxxxxxx>]

On 07/20/2015 12:15 PM, David Vrabel wrote:
> On 10/07/15 15:42, Juergen Gross wrote:
> > When dom0 is being ballooned balloon_process() will hold the balloon
> > mutex until it is finished. This will block e.g. creation of new
> > domains as the device backends for the new domain need some
> > autoballooned pages for the ring buffers.
> >
> > Avoid this by releasing the balloon mutex from time to time during
> > ballooning. Add a state variable to indicate one balloon_process()
> > is active to avoid multiple balloon processes fighting for the mutex.
> Is this state variable necessary? balloon_process() is a work item so
> there should only be one instance of it running anyway, yes?
Hmm, yes. I've been following the comment above balloon_process()
which suggested the possibility of multiple active instances.

I'll send another version of the patch with an updated comment and
removed state variable.


Juergen


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