In message <4e69afcf.3040...@linux.vnet.ibm.com> you wrote:
> On Friday 09 September 2011 07:08 AM, Michael Neuling wrote:
> >> perf events, powerpc: Add POWER7 stalled-cycles-frontend/backend events
> >>
> >> Extent the POWER7 PMU driver with definitions
> >> for generic front-end and back-end stall events.
> >
> > Anshuman,
> >
> > Can you explain what these P7 events actually are and how they relate to
> > Ingo's original comment on this in
> > 8f62242246351b5a4bc0c1f00c0c7003edea128a
> >
> > Both events limit performance: most front end stalls tend to be
> > caused by branch misprediction or instruction fetch cachemisses,
> > backend stalls can be caused by various resource shortages or
> > inefficient instruction scheduling.
> >
> As explained in Ingo's original comment, the exact definitions of the
> stall events are very much processor specific as different things mean
> different in their respective instruction pipeline. These two Power7
> raw events are the closest approximation to the concept detailed in
> Ingo's comment.
> >>
> >> Signed-off-by: Anshuman Khandual <khand...@linux.vnet.ibm.com>
> >>
> >> diff --git a/arch/powerpc/kernel/power7-pmu.c b/arch/powerpc/kernel/power7
-pmu.c
> >> index 593740f..e5d2844 100644
> >> --- a/arch/powerpc/kernel/power7-pmu.c
> >> +++ b/arch/powerpc/kernel/power7-pmu.c
> >> @@ -297,6 +297,8 @@ static void power7_disable_pmc(unsigned int pmc, unsig
ned long mmcr[])
> >>
> >> static int power7_generic_events[] = {
> >> [PERF_COUNT_HW_CPU_CYCLES] = 0x1e,
> >> + [PERF_COUNT_HW_STALLED_CYCLES_FRONTEND] = 0x100f8, /* GCT_NOSLOT_CYC */
> >
> > eg. Is this Global Completion Table (GCT) empty?
> Yes, it means cycles when the Global Completion Table has no slots from this
> thread
> >
> >> + [PERF_COUNT_HW_STALLED_CYCLES_BACKEND] = 0x4000a, /* CMPLU_STALL
*/
> >
> > eg. Is this instruction completion stall?
> Yes, it means no groups completed and GCT not empty
I agree, I think they match what Ingo is trying to achieve.
Can you add these descriptions to the patch and resubmit please?
If you can find similar events for power4/5/5+/6 that would be great too
submit too.
FWIW, the patch compiles and runs for me.
Mikey
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