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Re: [Xen-devel] Need help with fixing the Xen waitqueue feature


  • To: Olaf Hering <olaf@xxxxxxxxx>
  • From: Keir Fraser <keir@xxxxxxx>
  • Date: Wed, 23 Nov 2011 18:23:56 +0000
  • Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
  • Delivery-date: Wed, 23 Nov 2011 18:24:59 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AcyqDQ+aUPhC5IAn10agUiQsADt+og==
  • Thread-topic: [Xen-devel] Need help with fixing the Xen waitqueue feature

On 23/11/2011 18:06, "Olaf Hering" <olaf@xxxxxxxxx> wrote:

> On Wed, Nov 23, Keir Fraser wrote:
> 
>> On 23/11/2011 17:00, "Olaf Hering" <olaf@xxxxxxxxx> wrote:
>> 
>>> On Tue, Nov 22, Keir Fraser wrote:
>>> 
>>>> We obviously can't have dom0 going to sleep on paging work. This, at least,
>>>> isn't a wait-queue bug.
>>> 
>>> I had to rearrange some code in p2m_mem_paging_populate for my debug
>>> stuff. This led to an uninitialized req, and as a result req.flags
>>> sometimes had MEM_EVENT_FLAG_VCPU_PAUSED set. For some reason gcc did
>>> not catch that..
>>> Now waitqueues appear to work ok for me. Thanks!
>> 
>> Great. However, while eyeballing wait.c I spotted at least two bugs. I'm
>> pretty sure that the hypervisor will blow up pretty quickly when you resume
>> testing with multiple physical CPUs, for example. I need to create a couple
>> of fixup patches which I will then send to you for test.
> 
> Good, I will look forward for these fixes.
> 
>> By the way, did you test my patch to domain_crash when the stack-save area
>> isn't large enough?
> 
> I ran into the ->esp == 0 case right away, but I need to retest with a
> clean tree.

I think I have a test the wrong way round. This doesn't really matter now
anyway. As I say in my previous email, stack management will have to be
redone for waitqueues.

 -- Keir

> Olaf



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