On Tue, May 26, 2015 at 04:46:07AM -0700, Stephane Eranian wrote:
> On Tue, May 26, 2015 at 3:12 AM, Peter Zijlstra <pet...@infradead.org> wrote:
> > On Tue, May 26, 2015 at 02:24:38AM -0700, Stephane Eranian wrote:
> >> On Fri, May 22, 2015 at 6:40 AM, Peter Zijlstra <pet...@infradead.org>
> >> wrote:
> >> > On Fri, May 22, 2015 at 03:29:06PM +0200, Peter Zijlstra wrote:
> >> >> @@ -788,9 +788,9 @@ int x86_schedule_events(struct cpu_hw_ev
> >> >> x86_pmu.start_scheduling(cpuc);
> >> >>
> >> >> for (i = 0, wmin = X86_PMC_IDX_MAX, wmax = 0; i < n; i++) {
> >> >> + cpuc->event_constraint[i] = NULL;
> >> >
> But where is the code that says: skip reinstalling the constraint
> in intel_get_event_constraints() because there is already a (stale)
> one? I don't see where that is.
IIRC the problem was that the copy from c2 into c1:
if (c1 && (c1->flags & PERF_X86_EVENT_DYNAMIC)) {
bitmap_copy(c1->idxmsk, c2->idxmsk, X86_PMC_IDX_MAX);
c1->weight = c2->weight;
c2 = c1;
}
is incomplete. For instance, flags is not copied, and some code down the
line might check that and get wrong flags.
I'm not entirely sure I saw misbehaviour, but I figured I'd better close
that hole and rule out this is contributing to fail.
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