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Re: [Xen-devel] Fwd: [v3 14/15] Update Posted-Interrupts Descriptor during vCPU scheduling

> -----Original Message-----
> From: Dario Faggioli [mailto:dario.faggioli@xxxxxxxxxx]
> Sent: Friday, July 17, 2015 6:14 PM
> To: Wu, Feng
> Cc: Jan Beulich; Tian, Kevin; keir@xxxxxxx; George Dunlap;
> andrew.cooper3@xxxxxxxxxx; xen-devel; Zhang, Yang Z
> Subject: Re: [Xen-devel] Fwd: [v3 14/15] Update Posted-Interrupts Descriptor
> during vCPU scheduling
> On Fri, 2015-07-17 at 07:46 +0000, Wu, Feng wrote:
> > Hi Dario,
> >
> Hi,
> > I finished the new patch with arch hooks, but seems something is wrong,
> > after assigning the NIC to guest, I ping some guy from the guest, the
> > latency is too big.
> >
> Ok. What numbers are we talking about, just to have an idea.

It can be hundreds of microseconds.

> > So far I've not found the reason after debugging the code
> > for some time.
> >
> Yeah, well, I can imagine it's a bit tricky.
> > I post the path here to see if you can find any obvious logic
> > errors in it. Or could you have a look at it to double check whether this 
> > patch
> > exactly does the same thing as
> > [v3 14/15] Update Posted-Interrupts Descriptor during vCPU scheduling,
> > which works well.
> >
> A will certainly have a look, and I'll try to compare it with the
> previous one.
> However, I guess you are testing the new version of the series, where
> more things than just this changed, or are you actually comparing
> branches, the only difference between which is the use of the new or the
> old patch?

Yes, I only changed this scheduler things compared to the old version.

> Also, I don't have any PI enabled hardware handy so, please, keep
> looking and debugging yourself, as you're in a better position than me,
> as I can only do code inspection.
> I'll let you know what I find.

Sure, I will continue to debug it. Since you are the scheduler expert, it
should be helpful if you can give some comments at the same time!:)


> Regards,
> Dario
> --
> <<This happens because I choose it to happen!>> (Raistlin Majere)
> -----------------------------------------------------------------
> Dario Faggioli, Ph.D, http://about.me/dario.faggioli
> Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)
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