From 8113070d6639d2245c6c79afb8df42cedab30540 Mon Sep 17 00:00:00 2001 From: Stephane Eranian Date: Thu, 21 Jan 2010 17:39:01 +0200 Subject: [PATCH] perf_events: Add fast-path to the rescheduling code Implement correct fastpath scheduling, i.e., reuse previous assignment. Signed-off-by: Stephane Eranian [ split from larger patch] Signed-off-by: Peter Zijlstra LKML-Reference: <4b588464.1818d00a.4456.383b@mx.google.com> Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_event.c | 91 +++++++++++++++++++++----------- 1 file changed, 61 insertions(+), 30 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 995ac4ae379c..0bd23d01af34 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -1244,6 +1244,46 @@ static int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign) constraints[i]); } + /* + * fastpath, try to reuse previous register + */ + for (i = 0, num = n; i < n; i++, num--) { + hwc = &cpuc->event_list[i]->hw; + c = (unsigned long *)constraints[i]; + + /* never assigned */ + if (hwc->idx == -1) + break; + + /* constraint still honored */ + if (!test_bit(hwc->idx, c)) + break; + + /* not already used */ + if (test_bit(hwc->idx, used_mask)) + break; + +#if 0 + pr_debug("CPU%d fast config=0x%llx idx=%d assign=%c\n", + smp_processor_id(), + hwc->config, + hwc->idx, + assign ? 'y' : 'n'); +#endif + + set_bit(hwc->idx, used_mask); + if (assign) + assign[i] = hwc->idx; + } + if (!num) + goto done; + + /* + * begin slow path + */ + + bitmap_zero(used_mask, X86_PMC_IDX_MAX); + /* * weight = number of possible counters * @@ -1263,10 +1303,9 @@ static int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign) if (x86_pmu.num_events_fixed) wmax++; - num = n; - for (w = 1; num && w <= wmax; w++) { + for (w = 1, num = n; num && w <= wmax; w++) { /* for each event */ - for (i = 0; i < n; i++) { + for (i = 0; num && i < n; i++) { c = (unsigned long *)constraints[i]; hwc = &cpuc->event_list[i]->hw; @@ -1274,28 +1313,6 @@ static int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign) if (weight != w) continue; - /* - * try to reuse previous assignment - * - * This is possible despite the fact that - * events or events order may have changed. - * - * What matters is the level of constraints - * of an event and this is constant for now. - * - * This is possible also because we always - * scan from most to least constrained. Thus, - * if a counter can be reused, it means no, - * more constrained events, needed it. And - * next events will either compete for it - * (which cannot be solved anyway) or they - * have fewer constraints, and they can use - * another counter. - */ - j = hwc->idx; - if (j != -1 && !test_bit(j, used_mask)) - goto skip; - for_each_bit(j, c, X86_PMC_IDX_MAX) { if (!test_bit(j, used_mask)) break; @@ -1303,22 +1320,23 @@ static int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign) if (j == X86_PMC_IDX_MAX) break; -skip: - set_bit(j, used_mask); #if 0 - pr_debug("CPU%d config=0x%llx idx=%d assign=%c\n", + pr_debug("CPU%d slow config=0x%llx idx=%d assign=%c\n", smp_processor_id(), hwc->config, j, assign ? 'y' : 'n'); #endif + set_bit(j, used_mask); + if (assign) assign[i] = j; num--; } } +done: /* * scheduling failed or is just a simulation, * free resources if necessary @@ -1357,7 +1375,7 @@ static int collect_events(struct cpu_hw_events *cpuc, struct perf_event *leader, list_for_each_entry(event, &leader->sibling_list, group_entry) { if (!is_x86_event(event) || - event->state == PERF_EVENT_STATE_OFF) + event->state <= PERF_EVENT_STATE_OFF) continue; if (n >= max_count) @@ -2184,6 +2202,8 @@ static void amd_get_event_constraints(struct cpu_hw_events *cpuc, struct perf_event *event, u64 *idxmsk) { + /* no constraints, means supports all generic counters */ + bitmap_fill((unsigned long *)idxmsk, x86_pmu.num_events); } static int x86_event_sched_in(struct perf_event *event, @@ -2258,7 +2278,7 @@ int hw_perf_group_sched_in(struct perf_event *leader, n1 = 1; list_for_each_entry(sub, &leader->sibling_list, group_entry) { - if (sub->state != PERF_EVENT_STATE_OFF) { + if (sub->state > PERF_EVENT_STATE_OFF) { ret = x86_event_sched_in(sub, cpuctx, cpu); if (ret) goto undo; @@ -2613,12 +2633,23 @@ static int validate_group(struct perf_event *event) const struct pmu *hw_perf_event_init(struct perf_event *event) { + const struct pmu *tmp; int err; err = __hw_perf_event_init(event); if (!err) { + /* + * we temporarily connect event to its pmu + * such that validate_group() can classify + * it as an x86 event using is_x86_event() + */ + tmp = event->pmu; + event->pmu = &pmu; + if (event->group_leader != event) err = validate_group(event); + + event->pmu = tmp; } if (err) { if (event->destroy) -- 2.20.1