perf/x86: Optimize x86_schedule_events()

Now that cpuc->event_constraint[] is retained, we can avoid calling
get_event_constraints() over and over again.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 2795301..fa88acf 100644 (file)
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -858,8 +858,17 @@ int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign)
                x86_pmu.start_scheduling(cpuc);
 
        for (i = 0, wmin = X86_PMC_IDX_MAX, wmax = 0; i < n; i++) {
-               c = x86_pmu.get_event_constraints(cpuc, i, cpuc->event_list[i]);
-               cpuc->event_constraint[i] = c;
+               c = cpuc->event_constraint[i];
+
+               /*
+                * Request constraints for new events; or for those events that
+                * have a dynamic constraint -- for those the constraint can
+                * change due to external factors (sibling state, allow_tfa).
+                */
+               if (!c || (c->flags & PERF_X86_EVENT_DYNAMIC)) {
+                       c = x86_pmu.get_event_constraints(cpuc, i, cpuc->event_list[i]);
+                       cpuc->event_constraint[i] = c;
+               }
 
                wmin = min(wmin, c->weight);
                wmax = max(wmax, c->weight);

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index a80015f..62394e1 100644 (file)
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -2945,7 +2945,8 @@ intel_get_event_constraints(struct cpu_hw_events *cpuc, int idx,
         * - dynamic constraint: handled by intel_get_excl_constraints()
         */
        c2 = __intel_get_event_constraints(cpuc, idx, event);
-       if (c1 && (c1->flags & PERF_X86_EVENT_DYNAMIC)) {
+       if (c1) {
+               WARN_ON_ONCE(!(c1->flags & PERF_X86_EVENT_DYNAMIC));
                bitmap_copy(c1->idxmsk, c2->idxmsk, X86_PMC_IDX_MAX);
                c1->weight = c2->weight;
                c2 = c1;