perf_event: x86: Optimize the constraint searching bits
Peter Zijlstra [Fri, 22 Jan 2010 15:32:17 +0000 (16:32 +0100)]
Instead of copying bitmasks around, pass pointers to the constraint
structure.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
LKML-Reference: <20100122155535.887853503@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/cpu/perf_event.c

index 4d1ed10..092ad56 100644 (file)
@@ -134,12 +134,14 @@ struct x86_pmu {
        u64             intel_ctrl;
        void            (*enable_bts)(u64 config);
        void            (*disable_bts)(void);
-       void            (*get_event_constraints)(struct cpu_hw_events *cpuc,
-                                                struct perf_event *event,
-                                                unsigned long *idxmsk);
+
+       struct event_constraint *
+                       (*get_event_constraints)(struct cpu_hw_events *cpuc,
+                                                struct perf_event *event);
+
        void            (*put_event_constraints)(struct cpu_hw_events *cpuc,
                                                 struct perf_event *event);
-       const struct event_constraint *event_constraints;
+       struct event_constraint *event_constraints;
 };
 
 static struct x86_pmu x86_pmu __read_mostly;
@@ -1242,17 +1244,15 @@ static int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign)
 {
        int i, j , w, num;
        int weight, wmax;
-       unsigned long *c;
-       unsigned long constraints[X86_PMC_IDX_MAX][BITS_TO_LONGS(X86_PMC_IDX_MAX)];
+       struct event_constraint *c, *constraints[X86_PMC_IDX_MAX];
        unsigned long used_mask[BITS_TO_LONGS(X86_PMC_IDX_MAX)];
        struct hw_perf_event *hwc;
 
        bitmap_zero(used_mask, X86_PMC_IDX_MAX);
 
        for (i = 0; i < n; i++) {
-               x86_pmu.get_event_constraints(cpuc,
-                                             cpuc->event_list[i],
-                                             constraints[i]);
+               constraints[i] =
+                 x86_pmu.get_event_constraints(cpuc, cpuc->event_list[i]);
        }
 
        /*
@@ -1267,7 +1267,7 @@ static int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign)
                        break;
 
                /* constraint still honored */
-               if (!test_bit(hwc->idx, c))
+               if (!test_bit(hwc->idx, c->idxmsk))
                        break;
 
                /* not already used */
@@ -1320,11 +1320,11 @@ static int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign)
                        c = constraints[i];
                        hwc = &cpuc->event_list[i]->hw;
 
-                       weight = bitmap_weight(c, X86_PMC_IDX_MAX);
+                       weight = bitmap_weight(c->idxmsk, X86_PMC_IDX_MAX);
                        if (weight != w)
                                continue;
 
-                       for_each_bit(j, c, X86_PMC_IDX_MAX) {
+                       for_each_bit(j, c->idxmsk, X86_PMC_IDX_MAX) {
                                if (!test_bit(j, used_mask))
                                        break;
                        }
@@ -2155,11 +2155,13 @@ perf_event_nmi_handler(struct notifier_block *self,
        return NOTIFY_STOP;
 }
 
+static struct event_constraint unconstrained;
+
 static struct event_constraint bts_constraint =
        EVENT_CONSTRAINT(0, 1ULL << X86_PMC_IDX_FIXED_BTS, 0);
 
-static int intel_special_constraints(struct perf_event *event,
-                                    unsigned long *idxmsk)
+static struct event_constraint *
+intel_special_constraints(struct perf_event *event)
 {
        unsigned int hw_event;
 
@@ -2169,46 +2171,34 @@ static int intel_special_constraints(struct perf_event *event,
                      x86_pmu.event_map(PERF_COUNT_HW_BRANCH_INSTRUCTIONS)) &&
                     (event->hw.sample_period == 1))) {
 
-               bitmap_copy((unsigned long *)idxmsk,
-                           (unsigned long *)bts_constraint.idxmsk,
-                           X86_PMC_IDX_MAX);
-               return 1;
+               return &bts_constraint;
        }
-       return 0;
+       return NULL;
 }
 
-static void intel_get_event_constraints(struct cpu_hw_events *cpuc,
-                                       struct perf_event *event,
-                                       unsigned long *idxmsk)
+static struct event_constraint *
+intel_get_event_constraints(struct cpu_hw_events *cpuc, struct perf_event *event)
 {
-       const struct event_constraint *c;
+       struct event_constraint *c;
 
-       /*
-        * cleanup bitmask
-        */
-       bitmap_zero(idxmsk, X86_PMC_IDX_MAX);
-
-       if (intel_special_constraints(event, idxmsk))
-               return;
+       c = intel_special_constraints(event);
+       if (c)
+               return c;
 
        if (x86_pmu.event_constraints) {
                for_each_event_constraint(c, x86_pmu.event_constraints) {
-                       if ((event->hw.config & c->cmask) == c->code) {
-                               bitmap_copy(idxmsk, c->idxmsk, X86_PMC_IDX_MAX);
-                               return;
-                       }
+                       if ((event->hw.config & c->cmask) == c->code)
+                               return c;
                }
        }
-       /* no constraints, means supports all generic counters */
-       bitmap_fill((unsigned long *)idxmsk, x86_pmu.num_events);
+
+       return &unconstrained;
 }
 
-static void amd_get_event_constraints(struct cpu_hw_events *cpuc,
-                                     struct perf_event *event,
-                                     unsigned long *idxmsk)
+static struct event_constraint *
+amd_get_event_constraints(struct cpu_hw_events *cpuc, struct perf_event *event)
 {
-       /* no constraints, means supports all generic counters */
-       bitmap_fill(idxmsk, x86_pmu.num_events);
+       return &unconstrained;
 }
 
 static int x86_event_sched_in(struct perf_event *event,
@@ -2576,6 +2566,9 @@ void __init init_hw_perf_events(void)
        perf_events_lapic_init();
        register_die_notifier(&perf_event_nmi_notifier);
 
+       unconstrained = (struct event_constraint)
+               EVENT_CONSTRAINT(0, (1ULL << x86_pmu.num_events) - 1, 0);
+
        pr_info("... version:                %d\n",     x86_pmu.version);
        pr_info("... bit width:              %d\n",     x86_pmu.event_bits);
        pr_info("... generic registers:      %d\n",     x86_pmu.num_events);