On Wed, May 20, 2015 at 03:03:12PM +0200, Peter Zijlstra wrote:
> So new in this release is:
>
> static void intel_put_event_constraints(struct cpu_hw_events *cpuc,
> struct perf_event *event)
> {
> ...
>
> /* cleanup dynamic constraint */
> if (c && (c->flags & PERF_X86_EVENT_DYNAMIC))
> event->hw.constraint = NULL;
> }
>
> Which is the only place that value is ever cleared...
>
> Now, I've not quite figured out how that can intersect with scheduling,
> typically we only call put_event_constraints() when we're done with the
> event.
Related to that; intel_commit_scheduling() has:
c = event->hw.constraint;
if (!c)
return;
Stephane, how can that ever be?
x86_schedule_events() does:
hwc->constraint = get_event_constraints()
for all events, and intel_get_event_constraints() will _always_ return a
valid constraint -- &unconstrained if nothing else.
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