Re: [PATCH 9/9] perf/x86: add syfs entry to disable HT bug workaround

Borislav Petkov
2014-06-05T15:19:46Z

On Thu, Jun 05, 2014 at 05:45:24PM +0300, Maria Dimakopoulou wrote:
> The issue is that the outcoming leaked counts are not compensated
> by the incoming leaked counts of the sibling thread. With the workaround,
> corrupting events are always scheduled with an empty sibling counter.
> This means that their leaked counts are lost. So it is expected to see
> lower counts with the workaround. Note that this is not a side-effect of
> the workaround; leaked counts are expected to be lost with nothing
> measured on the sibling counter in general.
>
> In a second series we intend to re-integrate the counts for counting mode
> events. The workaround makes this easier because it guarantees
> that the sibling counter is unused, thus its counts are purely leaked
> counts and they can be safely re-integrated.

IIUC, sounds to me like reintegrating the leaked counts from the unused
counter should be part of the workaround too, not a second series...

--
Regards/Gruss,
Boris.

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