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From: Peter Zijlstra on 7 Jun 2010 05:50
On Thu, 2010-06-03 at 01:23 +0400, Cyrill Gorcunov wrote:
> On Netburst PMU we need a second write to a performance counter
> due to cpu erratum.
>
> A simple flag test instead of alternative instructions was choosen
> because wrmsrl is already a macro and if virtualization is turned
> on will need an additional wrapper call which is more expencise.
>
> nb: we should propably switch to jump-labels as only this facility
> reach the mainline.

OK. Thanks Cyrill.


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From: Lin Ming on 8 Jun 2010 05:30
On Mon, 2010-06-07 at 17:48 +0800, Peter Zijlstra wrote:
> On Thu, 2010-06-03 at 01:23 +0400, Cyrill Gorcunov wrote:
> > On Netburst PMU we need a second write to a performance counter
> > due to cpu erratum.
> >
> > A simple flag test instead of alternative instructions was choosen
> > because wrmsrl is already a macro and if virtualization is turned
> > on will need an additional wrapper call which is more expencise.
> >
> > nb: we should propably switch to jump-labels as only this facility
> > reach the mainline.
>
> OK. Thanks Cyrill.


I tested this patch and it works well for pre-defined events.

Lin Ming

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