On Mon, May 06, 2013 at 07:44:19PM +0200, Stephane Eranian wrote: > On Thu, May 2, 2013 at 9:37 AM, Peter Zijlstra <pet...@infradead.org> wrote: > > On Wed, Apr 24, 2013 at 04:04:54PM -0700, Andi Kleen wrote: > >> From: Andi Kleen <a...@linux.intel.com> > >> > >> The PEBS documentation in the Intel SDM 18.6.1.1 states: > >> > >> """ > >> PEBS events are only valid when the following fields of IA32_PERFEVTSELx > >> are all > >> zero: AnyThread, Edge, Invert, CMask. > >> """ > >> > >> Since we had problems with this earlier, don't allow cmask, any, edge, > >> invert > >> as raw events, except for the ones explicitly listed as pebs_aliases. > > > > If its a simple matter of crap in crap out without affecting anything else > > we > > shouldn't do anything. > > > The problem here is that you are sampling an instruction which did not cause > the event you are measuring. Remember that using cmask, changes the > nature of what's being measured (from event to cycles).
Yeah.. I don't see the problem though. If you're using cmask and the like you're supposed to know wth you're doing; which includes knowing your cpu and what it thinks of such an event. The only reason to disallow events is if they (badly) interact with other counters. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
