diff options
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event.c | 34 | ||||
| -rw-r--r-- | include/linux/perf_event.h | 2 |
2 files changed, 30 insertions, 6 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 96cfc1a..a920f17 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -90,6 +90,7 @@ struct cpu_hw_events { int n_events; int n_added; int assign[X86_PMC_IDX_MAX]; /* event to counter assignment */ + u64 tags[X86_PMC_IDX_MAX]; struct perf_event *event_list[X86_PMC_IDX_MAX]; /* in enabled order */ }; @@ -1142,6 +1143,8 @@ static int __hw_perf_event_init(struct perf_event *event) hwc->config = ARCH_PERFMON_EVENTSEL_INT; hwc->idx = -1; + hwc->last_cpu = -1; + hwc->last_tag = ~0ULL; /* * Count user and OS events unless requested not to. @@ -1457,11 +1460,14 @@ static int collect_events(struct cpu_hw_events *cpuc, struct perf_event *leader, return n; } - static inline void x86_assign_hw_event(struct perf_event *event, - struct hw_perf_event *hwc, int idx) + struct cpu_hw_events *cpuc, int i) { - hwc->idx = idx; + struct hw_perf_event *hwc = &event->hw; + + hwc->idx = cpuc->assign[i]; + hwc->last_cpu = smp_processor_id(); + hwc->last_tag = ++cpuc->tags[i]; if (hwc->idx == X86_PMC_IDX_FIXED_BTS) { hwc->config_base = 0; @@ -1480,6 +1486,15 @@ static inline void x86_assign_hw_event(struct perf_event *event, } } +static inline int match_prev_assignment(struct hw_perf_event *hwc, + struct cpu_hw_events *cpuc, + int i) +{ + return hwc->idx == cpuc->assign[i] && + hwc->last_cpu == smp_processor_id() && + hwc->last_tag == cpuc->tags[i]; +} + static void __x86_pmu_disable(struct perf_event *event, struct cpu_hw_events *cpuc); void hw_perf_enable(void) @@ -1508,7 +1523,14 @@ void hw_perf_enable(void) event = cpuc->event_list[i]; hwc = &event->hw; - if (hwc->idx == -1 || hwc->idx == cpuc->assign[i]) + /* + * we can avoid reprogramming counter if: + * - assigned same counter as last time + * - running on same CPU as last time + * - no other event has used the counter since + */ + if (hwc->idx == -1 || + match_prev_assignment(hwc, cpuc, i)) continue; __x86_pmu_disable(event, cpuc); @@ -1522,12 +1544,12 @@ void hw_perf_enable(void) hwc = &event->hw; if (hwc->idx == -1) { - x86_assign_hw_event(event, hwc, cpuc->assign[i]); + x86_assign_hw_event(event, cpuc, i); x86_perf_event_set_period(event, hwc, hwc->idx); } /* * need to mark as active because x86_pmu_disable() - * clear active_mask and eventsp[] yet it preserves + * clear active_mask and events[] yet it preserves * idx */ set_bit(hwc->idx, cpuc->active_mask); diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 556b0f4..071a7db 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -478,9 +478,11 @@ struct hw_perf_event { union { struct { /* hardware */ u64 config; + u64 last_tag; unsigned long config_base; unsigned long event_base; int idx; + int last_cpu; }; struct { /* software */ s64 remaining; |
