From 60db5e09c13109b13830cc9dcae688003fd39e79 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 15 May 2009 15:19:28 +0200 Subject: [PATCH] perf_counter: frequency based adaptive irq_period Instead of specifying the irq_period for a counter, provide a target interrupt frequency and dynamically adapt the irq_period to match this frequency. [ Impact: new perf-counter attribute/feature ] Signed-off-by: Peter Zijlstra Cc: Paul Mackerras Cc: Corey Ashford Cc: Arnaldo Carvalho de Melo LKML-Reference: <20090515132018.646195868@chello.nl> Signed-off-by: Ingo Molnar --- arch/powerpc/kernel/perf_counter.c | 13 +++--- arch/x86/kernel/cpu/perf_counter.c | 9 ++--- include/linux/perf_counter.h | 10 ++++- kernel/perf_counter.c | 63 ++++++++++++++++++++++++------ 4 files changed, 68 insertions(+), 27 deletions(-) diff --git a/arch/powerpc/kernel/perf_counter.c b/arch/powerpc/kernel/perf_counter.c index bb1b463c136..db8d5cafc15 100644 --- a/arch/powerpc/kernel/perf_counter.c +++ b/arch/powerpc/kernel/perf_counter.c @@ -534,7 +534,7 @@ void hw_perf_enable(void) continue; } val = 0; - if (counter->hw_event.irq_period) { + if (counter->hw.irq_period) { left = atomic64_read(&counter->hw.period_left); if (left < 0x80000000L) val = 0x80000000L - left; @@ -829,8 +829,6 @@ const struct pmu *hw_perf_counter_init(struct perf_counter *counter) if (!ppmu) return ERR_PTR(-ENXIO); - if ((s64)counter->hw_event.irq_period < 0) - return ERR_PTR(-EINVAL); if (!perf_event_raw(&counter->hw_event)) { ev = perf_event_id(&counter->hw_event); if (ev >= ppmu->n_generic || ppmu->generic_events[ev] == 0) @@ -901,7 +899,7 @@ const struct pmu *hw_perf_counter_init(struct perf_counter *counter) counter->hw.config = events[n]; counter->hw.counter_base = cflags[n]; - atomic64_set(&counter->hw.period_left, counter->hw_event.irq_period); + atomic64_set(&counter->hw.period_left, counter->hw.irq_period); /* * See if we need to reserve the PMU. @@ -934,6 +932,7 @@ const struct pmu *hw_perf_counter_init(struct perf_counter *counter) static void record_and_restart(struct perf_counter *counter, long val, struct pt_regs *regs, int nmi) { + u64 period = counter->hw.irq_period; s64 prev, delta, left; int record = 0; @@ -948,11 +947,11 @@ static void record_and_restart(struct perf_counter *counter, long val, */ val = 0; left = atomic64_read(&counter->hw.period_left) - delta; - if (counter->hw_event.irq_period) { + if (period) { if (left <= 0) { - left += counter->hw_event.irq_period; + left += period; if (left <= 0) - left = counter->hw_event.irq_period; + left = period; record = 1; } if (left < 0x80000000L) diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c index 5a7f718eb1e..886dcf334bc 100644 --- a/arch/x86/kernel/cpu/perf_counter.c +++ b/arch/x86/kernel/cpu/perf_counter.c @@ -286,11 +286,8 @@ static int __hw_perf_counter_init(struct perf_counter *counter) hwc->nmi = 1; } - hwc->irq_period = hw_event->irq_period; - if ((s64)hwc->irq_period <= 0 || hwc->irq_period > x86_pmu.max_period) - hwc->irq_period = x86_pmu.max_period; - - atomic64_set(&hwc->period_left, hwc->irq_period); + atomic64_set(&hwc->period_left, + min(x86_pmu.max_period, hwc->irq_period)); /* * Raw event type provide the config in the event structure @@ -458,7 +455,7 @@ x86_perf_counter_set_period(struct perf_counter *counter, struct hw_perf_counter *hwc, int idx) { s64 left = atomic64_read(&hwc->period_left); - s64 period = hwc->irq_period; + s64 period = min(x86_pmu.max_period, hwc->irq_period); int err; /* diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h index e543ecc129f..004b6e162b9 100644 --- a/include/linux/perf_counter.h +++ b/include/linux/perf_counter.h @@ -130,7 +130,11 @@ struct perf_counter_hw_event { */ __u64 config; - __u64 irq_period; + union { + __u64 irq_period; + __u64 irq_freq; + }; + __u32 record_type; __u32 read_format; @@ -146,8 +150,9 @@ struct perf_counter_hw_event { mmap : 1, /* include mmap data */ munmap : 1, /* include munmap data */ comm : 1, /* include comm data */ + freq : 1, /* use freq, not period */ - __reserved_1 : 52; + __reserved_1 : 51; __u32 extra_config_len; __u32 wakeup_events; /* wakeup every n events */ @@ -337,6 +342,7 @@ struct hw_perf_counter { atomic64_t prev_count; u64 irq_period; atomic64_t period_left; + u64 interrupts; #endif }; diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index 93f4a0e4b87..0ad1db4f3d6 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -1046,6 +1046,38 @@ int perf_counter_task_enable(void) return 0; } +void perf_adjust_freq(struct perf_counter_context *ctx) +{ + struct perf_counter *counter; + u64 irq_period; + u64 events, period; + s64 delta; + + spin_lock(&ctx->lock); + list_for_each_entry(counter, &ctx->counter_list, list_entry) { + if (counter->state != PERF_COUNTER_STATE_ACTIVE) + continue; + + if (!counter->hw_event.freq || !counter->hw_event.irq_freq) + continue; + + events = HZ * counter->hw.interrupts * counter->hw.irq_period; + period = div64_u64(events, counter->hw_event.irq_freq); + + delta = (s64)(1 + period - counter->hw.irq_period); + delta >>= 1; + + irq_period = counter->hw.irq_period + delta; + + if (!irq_period) + irq_period = 1; + + counter->hw.irq_period = irq_period; + counter->hw.interrupts = 0; + } + spin_unlock(&ctx->lock); +} + /* * Round-robin a context's counters: */ @@ -1081,6 +1113,9 @@ void perf_counter_task_tick(struct task_struct *curr, int cpu) cpuctx = &per_cpu(perf_cpu_context, cpu); ctx = &curr->perf_counter_ctx; + perf_adjust_freq(&cpuctx->ctx); + perf_adjust_freq(ctx); + perf_counter_cpu_sched_out(cpuctx); __perf_counter_task_sched_out(ctx); @@ -2382,6 +2417,8 @@ int perf_counter_overflow(struct perf_counter *counter, int events = atomic_read(&counter->event_limit); int ret = 0; + counter->hw.interrupts++; + /* * XXX event_limit might not quite work as expected on inherited * counters @@ -2450,6 +2487,7 @@ static enum hrtimer_restart perf_swcounter_hrtimer(struct hrtimer *hrtimer) enum hrtimer_restart ret = HRTIMER_RESTART; struct perf_counter *counter; struct pt_regs *regs; + u64 period; counter = container_of(hrtimer, struct perf_counter, hw.hrtimer); counter->pmu->read(counter); @@ -2468,7 +2506,8 @@ static enum hrtimer_restart perf_swcounter_hrtimer(struct hrtimer *hrtimer) ret = HRTIMER_NORESTART; } - hrtimer_forward_now(hrtimer, ns_to_ktime(counter->hw.irq_period)); + period = max_t(u64, 10000, counter->hw.irq_period); + hrtimer_forward_now(hrtimer, ns_to_ktime(period)); return ret; } @@ -2629,8 +2668,9 @@ static int cpu_clock_perf_counter_enable(struct perf_counter *counter) hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); hwc->hrtimer.function = perf_swcounter_hrtimer; if (hwc->irq_period) { + u64 period = max_t(u64, 10000, hwc->irq_period); __hrtimer_start_range_ns(&hwc->hrtimer, - ns_to_ktime(hwc->irq_period), 0, + ns_to_ktime(period), 0, HRTIMER_MODE_REL, 0); } @@ -2679,8 +2719,9 @@ static int task_clock_perf_counter_enable(struct perf_counter *counter) hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); hwc->hrtimer.function = perf_swcounter_hrtimer; if (hwc->irq_period) { + u64 period = max_t(u64, 10000, hwc->irq_period); __hrtimer_start_range_ns(&hwc->hrtimer, - ns_to_ktime(hwc->irq_period), 0, + ns_to_ktime(period), 0, HRTIMER_MODE_REL, 0); } @@ -2811,9 +2852,7 @@ static const struct pmu *tp_perf_counter_init(struct perf_counter *counter) static const struct pmu *sw_perf_counter_init(struct perf_counter *counter) { - struct perf_counter_hw_event *hw_event = &counter->hw_event; const struct pmu *pmu = NULL; - struct hw_perf_counter *hwc = &counter->hw; /* * Software counters (currently) can't in general distinguish @@ -2826,8 +2865,6 @@ static const struct pmu *sw_perf_counter_init(struct perf_counter *counter) case PERF_COUNT_CPU_CLOCK: pmu = &perf_ops_cpu_clock; - if (hw_event->irq_period && hw_event->irq_period < 10000) - hw_event->irq_period = 10000; break; case PERF_COUNT_TASK_CLOCK: /* @@ -2839,8 +2876,6 @@ static const struct pmu *sw_perf_counter_init(struct perf_counter *counter) else pmu = &perf_ops_cpu_clock; - if (hw_event->irq_period && hw_event->irq_period < 10000) - hw_event->irq_period = 10000; break; case PERF_COUNT_PAGE_FAULTS: case PERF_COUNT_PAGE_FAULTS_MIN: @@ -2854,9 +2889,6 @@ static const struct pmu *sw_perf_counter_init(struct perf_counter *counter) break; } - if (pmu) - hwc->irq_period = hw_event->irq_period; - return pmu; } @@ -2872,6 +2904,7 @@ perf_counter_alloc(struct perf_counter_hw_event *hw_event, { const struct pmu *pmu; struct perf_counter *counter; + struct hw_perf_counter *hwc; long err; counter = kzalloc(sizeof(*counter), gfpflags); @@ -2907,6 +2940,12 @@ perf_counter_alloc(struct perf_counter_hw_event *hw_event, pmu = NULL; + hwc = &counter->hw; + if (hw_event->freq && hw_event->irq_freq) + hwc->irq_period = TICK_NSEC / hw_event->irq_freq; + else + hwc->irq_period = hw_event->irq_period; + /* * we currently do not support PERF_RECORD_GROUP on inherited counters */ -- 2.41.0