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

[Juergen Gross <jgross@suse.com>]

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