Re: [Xen-devel] [PATCH] Intel/vpmu: Use Intel VPMU quirk on all family 6 processors

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 05/30/2013 12:38 PM, George Dunlap wrote:
> On 05/30/2013 05:33 PM, Boris Ostrovsky wrote:
> > On 05/16/2013 08:30 AM, Jan Beulich wrote:
> > > > > > On 10.05.13 at 11:46, George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
> > > > > > wrote:
> > > > On Thu, May 9, 2013 at 9:45 PM, Boris Ostrovsky
> > > > <boris.ostrovsky@xxxxxxxxxx> wrote:
> > > > > On 05/09/2013 04:34 PM, Boris Ostrovsky wrote:
> > > > > > Currently only a few Intel models have VPMU workaround turned on. It
> > > > > > appears, however, that this issue exists on more models than what is
> > > > > > covered by check_pmc_quirk(). Since we don't know exactly which cpus
> > > > > > are affected we should turn this workaround on for all family 6
> > > > > > processors.
> > > > > Haitao,
> > > > >
> > > > > A few weeks ago we had an email thread about this issue
> > > > > (http://lists.xen.org/archives/html/xen-devel/2013-03/msg02618.html)
> > > > > Did you have a chance to clarify with your HW folks what this is?
> > > > >
> > > > > We kept hitting this on various models which is why I am suggesting
> > > > > this
> > > > > patch (and I think it should be considered for 4.3).
> > > > In principle it's a bug fix, and fine for 4.3.  But it would be good
> > > > to get some feedback from someone at Intel.
> > > Intel, anyone???
> > >
> > > Thanks, Jan
> > I haven't seen any responses from Intel folks about this issue.
> >
> > Do we wait for post-4.3?
> Our goals at this point:
> - Bug-free release
> - Awesome release
> - On-time release
>
> I take it that the main risk here is that vcpu for some models which 
> would have otherwise worked will not work anymore?
(I assume you meant vpmu, not vcpu). Yes, that would be the main risk.


-boris

> But at his point you *know* many models which don't work without it; 
> so on the whole I'm inclined to say that it's an "accept" on the 
> cost/benefits analysis.
>  -George

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