Messages in this thread | | | Date | Fri, 6 Jul 2012 03:04:29 +0200 | Subject | Re: [PATCH 2/5] perf, x86: Enable PDIR precise instruction profiling on IvyBridge | From | Stephane Eranian <> |
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On Thu, Jul 5, 2012 at 7:26 PM, Andi Kleen <ak@linux.intel.com> wrote: > On Thu, Jul 05, 2012 at 05:45:16PM +0200, Stephane Eranian wrote: >> On Tue, Jul 3, 2012 at 6:04 AM, Andi Kleen <andi@firstfloor.org> wrote: >> >> Well, the only way I can think of would be to request that the >> >> event be programmed with exclusive mode ALWAYS. That >> >> should not be to hard to add. >> > >> > I suspect it would need some special callbacks from the events core, >> > that's why I only tried on IvyBridge. >> >x >> You could simply add a check in the x86 init code like what is done >> with the pebs events and precise mode. > > Ah requiring the user to set exclusive? Maybe. Right now perf does not even > have an option to set it. Would seem user unfriendly to me though.
Yes, that's what I meant since the beginning. Require exclusive mode on the event is all we need to enforce the restriction. The scheduling would still only work on counter 1.
I know that perf record/stat do not support this but given the new event parser it should not too hard to add an excl term to the syntax. I have that in libpfm4 now as an option on events. That's clearly a perf_event option like period or freq and not a HW option like inv, edge.
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