Re: [PATCH] perf, x86: Add Silvermont (22nm Atom) support

From: Peter Zijlstra
Date: Thu Jul 18 2013 - 05:03:06 EST


On Thu, Jul 18, 2013 at 04:27:31PM +0800, Yan, Zheng wrote:
> On 07/18/2013 04:23 PM, Peter Zijlstra wrote:
> > On Thu, Jul 18, 2013 at 01:36:07PM +0800, Yan, Zheng wrote:
> >> +static struct event_constraint intel_slm_event_constraints[] __read_mostly =
> >> +{
> >> + FIXED_EVENT_CONSTRAINT(0x00c0, 0), /* INST_RETIRED.ANY */
> >> + FIXED_EVENT_CONSTRAINT(0x003c, 1), /* CPU_CLK_UNHALTED.CORE */
> >> + FIXED_EVENT_CONSTRAINT(0x013c, 2), /* CPU_CLK_UNHALTED.REF */
> >> + FIXED_EVENT_CONSTRAINT(0x0300, 2), /* pseudo CPU_CLK_UNHALTED.REF */
> >
> > So the normal event 0x13c and the fixed counter 2 are normally _not_ the
> > same. Are they for slm? Are you sure?
> >
>
> yes, I'm sure. see page 15-15 of http://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-optimization-manual.pdf

OK, then put in a comment how slm is 'special' and you might want to fix
intel_pmu_init():

if (x86_pmu.event_constraints) {
/*
* event on fixed counter2 (REF_CYCLES) only works on this
* counter, so do not extend mask to generic counters
*/
for_each_event_constraint(c, x86_pmu.event_constraints) {
if (c->cmask != FIXED_EVENT_FLAGS
|| c->idxmsk64 == INTEL_PMC_MSK_FIXED_REF_CYCLES) {
continue;
}

c->idxmsk64 |= (1ULL << x86_pmu.num_counters) - 1;
c->weight += x86_pmu.num_counters;
}
}

Since that explicitly skips the fixed counter 2 and doesn't extend its
constraint to include all other counters.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/