Subject: Re: [PATCH] powerpc: perf: Handle events that raise an exception without overflowing

From: Ingo Molnar <[email-masked]>
Date: Wed, 16 Mar 2011 13:50:53 +0100

* Anton Blanchard <[email-masked]> wrote:

> 
> Events on POWER7 can roll back if a speculative event doesn't
> eventually complete. Unfortunately in some rare cases they will
> raise a performance monitor exception. We need to catch this to
> ensure we reset the PMC. In all cases the PMC will be 256 or less
> cycles from overflow.
> 
> Signed-off-by: Anton Blanchard <[email-masked]>
> Cc: [email-masked]
> ---
> 
> I would prefer not to add the PVR check, but I think we want to limit
> this workaround to POWER7. Would a cpu feature be preferable?

There was no objection from the PowerPC folks so i'll send this fix Linuswards, ok?

Thanks,

	Ingo