diff options
Diffstat (limited to 'kernel/events/core.c')
-rw-r--r-- | kernel/events/core.c | 157 |
1 files changed, 106 insertions, 51 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index 32b48c8..7c3b9de 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -2300,6 +2300,9 @@ do { \ return div64_u64(dividend, divisor); } +static DEFINE_PER_CPU(int, perf_throttled_count); +static DEFINE_PER_CPU(u64, perf_throttled_seq); + static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count) { struct hw_perf_event *hwc = &event->hw; @@ -2325,16 +2328,29 @@ static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count) } } -static void perf_ctx_adjust_freq(struct perf_event_context *ctx, u64 period) +/* + * combine freq adjustment with unthrottling to avoid two passes over the + * events. At the same time, make sure, having freq events does not change + * the rate of unthrottling as that would introduce bias. + */ +static void perf_adjust_freq_unthr_context(struct perf_event_context *ctx, + int needs_unthr) { struct perf_event *event; struct hw_perf_event *hwc; - u64 interrupts, now; + u64 now, period = TICK_NSEC; s64 delta; - if (!ctx->nr_freq) + /* + * only need to iterate over all events iff: + * - context have events in frequency mode (needs freq adjust) + * - there are events to unthrottle on this cpu + */ + if (!(ctx->nr_freq || needs_unthr)) return; + raw_spin_lock(&ctx->lock); + list_for_each_entry_rcu(event, &ctx->event_list, event_entry) { if (event->state != PERF_EVENT_STATE_ACTIVE) continue; @@ -2344,13 +2360,8 @@ static void perf_ctx_adjust_freq(struct perf_event_context *ctx, u64 period) hwc = &event->hw; - interrupts = hwc->interrupts; - hwc->interrupts = 0; - - /* - * unthrottle events on the tick - */ - if (interrupts == MAX_INTERRUPTS) { + if (needs_unthr && hwc->interrupts == MAX_INTERRUPTS) { + hwc->interrupts = 0; perf_log_throttle(event, 1); event->pmu->start(event, 0); } @@ -2358,14 +2369,26 @@ static void perf_ctx_adjust_freq(struct perf_event_context *ctx, u64 period) if (!event->attr.freq || !event->attr.sample_freq) continue; - event->pmu->read(event); + /* + * stop the event and update event->count + */ + event->pmu->stop(event, PERF_EF_UPDATE); + now = local64_read(&event->count); delta = now - hwc->freq_count_stamp; hwc->freq_count_stamp = now; + /* + * restart the event + * reload only if value has changed + */ if (delta > 0) perf_adjust_period(event, period, delta); + + event->pmu->start(event, delta > 0 ? PERF_EF_RELOAD : 0); } + + raw_spin_unlock(&ctx->lock); } /* @@ -2388,16 +2411,13 @@ static void rotate_ctx(struct perf_event_context *ctx) */ static void perf_rotate_context(struct perf_cpu_context *cpuctx) { - u64 interval = (u64)cpuctx->jiffies_interval * TICK_NSEC; struct perf_event_context *ctx = NULL; - int rotate = 0, remove = 1, freq = 0; + int rotate = 0, remove = 1; if (cpuctx->ctx.nr_events) { remove = 0; if (cpuctx->ctx.nr_events != cpuctx->ctx.nr_active) rotate = 1; - if (cpuctx->ctx.nr_freq) - freq = 1; } ctx = cpuctx->task_ctx; @@ -2405,37 +2425,26 @@ static void perf_rotate_context(struct perf_cpu_context *cpuctx) remove = 0; if (ctx->nr_events != ctx->nr_active) rotate = 1; - if (ctx->nr_freq) - freq = 1; } - if (!rotate && !freq) + if (!rotate) goto done; perf_ctx_lock(cpuctx, cpuctx->task_ctx); perf_pmu_disable(cpuctx->ctx.pmu); - if (freq) { - perf_ctx_adjust_freq(&cpuctx->ctx, interval); - if (ctx) - perf_ctx_adjust_freq(ctx, interval); - } - - if (rotate) { - cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE); - if (ctx) - ctx_sched_out(ctx, cpuctx, EVENT_FLEXIBLE); + cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE); + if (ctx) + ctx_sched_out(ctx, cpuctx, EVENT_FLEXIBLE); - rotate_ctx(&cpuctx->ctx); - if (ctx) - rotate_ctx(ctx); + rotate_ctx(&cpuctx->ctx); + if (ctx) + rotate_ctx(ctx); - perf_event_sched_in(cpuctx, ctx, current); - } + perf_event_sched_in(cpuctx, ctx, current); perf_pmu_enable(cpuctx->ctx.pmu); perf_ctx_unlock(cpuctx, cpuctx->task_ctx); - done: if (remove) list_del_init(&cpuctx->rotation_list); @@ -2445,10 +2454,22 @@ void perf_event_task_tick(void) { struct list_head *head = &__get_cpu_var(rotation_list); struct perf_cpu_context *cpuctx, *tmp; + struct perf_event_context *ctx; + int throttled; WARN_ON(!irqs_disabled()); + __this_cpu_inc(perf_throttled_seq); + throttled = __this_cpu_xchg(perf_throttled_count, 0); + list_for_each_entry_safe(cpuctx, tmp, head, rotation_list) { + ctx = &cpuctx->ctx; + perf_adjust_freq_unthr_context(ctx, throttled); + + ctx = cpuctx->task_ctx; + if (ctx) + perf_adjust_freq_unthr_context(ctx, throttled); + if (cpuctx->jiffies_interval == 1 || !(jiffies % cpuctx->jiffies_interval)) perf_rotate_context(cpuctx); @@ -3208,10 +3229,6 @@ int perf_event_task_disable(void) return 0; } -#ifndef PERF_EVENT_INDEX_OFFSET -# define PERF_EVENT_INDEX_OFFSET 0 -#endif - static int perf_event_index(struct perf_event *event) { if (event->hw.state & PERF_HES_STOPPED) @@ -3220,21 +3237,26 @@ static int perf_event_index(struct perf_event *event) if (event->state != PERF_EVENT_STATE_ACTIVE) return 0; - return event->hw.idx + 1 - PERF_EVENT_INDEX_OFFSET; + return event->pmu->event_idx(event); } static void calc_timer_values(struct perf_event *event, + u64 *now, u64 *enabled, u64 *running) { - u64 now, ctx_time; + u64 ctx_time; - now = perf_clock(); - ctx_time = event->shadow_ctx_time + now; + *now = perf_clock(); + ctx_time = event->shadow_ctx_time + *now; *enabled = ctx_time - event->tstamp_enabled; *running = ctx_time - event->tstamp_running; } +void __weak perf_update_user_clock(struct perf_event_mmap_page *userpg, u64 now) +{ +} + /* * Callers need to ensure there can be no nesting of this function, otherwise * the seqlock logic goes bad. We can not serialize this because the arch @@ -3244,7 +3266,7 @@ void perf_event_update_userpage(struct perf_event *event) { struct perf_event_mmap_page *userpg; struct ring_buffer *rb; - u64 enabled, running; + u64 enabled, running, now; rcu_read_lock(); /* @@ -3256,7 +3278,7 @@ void perf_event_update_userpage(struct perf_event *event) * because of locking issue as we can be called in * NMI context */ - calc_timer_values(event, &enabled, &running); + calc_timer_values(event, &now, &enabled, &running); rb = rcu_dereference(event->rb); if (!rb) goto unlock; @@ -3272,7 +3294,7 @@ void perf_event_update_userpage(struct perf_event *event) barrier(); userpg->index = perf_event_index(event); userpg->offset = perf_event_count(event); - if (event->state == PERF_EVENT_STATE_ACTIVE) + if (userpg->index) userpg->offset -= local64_read(&event->hw.prev_count); userpg->time_enabled = enabled + @@ -3281,6 +3303,8 @@ void perf_event_update_userpage(struct perf_event *event) userpg->time_running = running + atomic64_read(&event->child_total_time_running); + perf_update_user_clock(userpg, now); + barrier(); ++userpg->lock; preempt_enable(); @@ -3538,6 +3562,8 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) event->mmap_user = get_current_user(); vma->vm_mm->pinned_vm += event->mmap_locked; + perf_event_update_userpage(event); + unlock: if (!ret) atomic_inc(&event->mmap_count); @@ -3769,7 +3795,7 @@ static void perf_output_read_group(struct perf_output_handle *handle, static void perf_output_read(struct perf_output_handle *handle, struct perf_event *event) { - u64 enabled = 0, running = 0; + u64 enabled = 0, running = 0, now; u64 read_format = event->attr.read_format; /* @@ -3782,7 +3808,7 @@ static void perf_output_read(struct perf_output_handle *handle, * NMI context */ if (read_format & PERF_FORMAT_TOTAL_TIMES) - calc_timer_values(event, &enabled, &running); + calc_timer_values(event, &now, &enabled, &running); if (event->attr.read_format & PERF_FORMAT_GROUP) perf_output_read_group(handle, event, enabled, running); @@ -4509,6 +4535,7 @@ static int __perf_event_overflow(struct perf_event *event, { int events = atomic_read(&event->event_limit); struct hw_perf_event *hwc = &event->hw; + u64 seq; int ret = 0; /* @@ -4518,14 +4545,20 @@ static int __perf_event_overflow(struct perf_event *event, if (unlikely(!is_sampling_event(event))) return 0; - if (unlikely(hwc->interrupts >= max_samples_per_tick)) { - if (throttle) { + seq = __this_cpu_read(perf_throttled_seq); + if (seq != hwc->interrupts_seq) { + hwc->interrupts_seq = seq; + hwc->interrupts = 1; + } else { + hwc->interrupts++; + if (unlikely(throttle + && hwc->interrupts >= max_samples_per_tick)) { + __this_cpu_inc(perf_throttled_count); hwc->interrupts = MAX_INTERRUPTS; perf_log_throttle(event, 0); ret = 1; } - } else - hwc->interrupts++; + } if (event->attr.freq) { u64 now = perf_clock(); @@ -4994,6 +5027,11 @@ static int perf_swevent_init(struct perf_event *event) return 0; } +static int perf_swevent_event_idx(struct perf_event *event) +{ + return 0; +} + static struct pmu perf_swevent = { .task_ctx_nr = perf_sw_context, @@ -5003,6 +5041,8 @@ static struct pmu perf_swevent = { .start = perf_swevent_start, .stop = perf_swevent_stop, .read = perf_swevent_read, + + .event_idx = perf_swevent_event_idx, }; #ifdef CONFIG_EVENT_TRACING @@ -5089,6 +5129,8 @@ static struct pmu perf_tracepoint = { .start = perf_swevent_start, .stop = perf_swevent_stop, .read = perf_swevent_read, + + .event_idx = perf_swevent_event_idx, }; static inline void perf_tp_register(void) @@ -5308,6 +5350,8 @@ static struct pmu perf_cpu_clock = { .start = cpu_clock_event_start, .stop = cpu_clock_event_stop, .read = cpu_clock_event_read, + + .event_idx = perf_swevent_event_idx, }; /* @@ -5380,6 +5424,8 @@ static struct pmu perf_task_clock = { .start = task_clock_event_start, .stop = task_clock_event_stop, .read = task_clock_event_read, + + .event_idx = perf_swevent_event_idx, }; static void perf_pmu_nop_void(struct pmu *pmu) @@ -5407,6 +5453,11 @@ static void perf_pmu_cancel_txn(struct pmu *pmu) perf_pmu_enable(pmu); } +static int perf_event_idx_default(struct perf_event *event) +{ + return event->hw.idx + 1; +} + /* * Ensures all contexts with the same task_ctx_nr have the same * pmu_cpu_context too. @@ -5493,6 +5544,7 @@ static int pmu_dev_alloc(struct pmu *pmu) if (!pmu->dev) goto out; + pmu->dev->groups = pmu->attr_groups; device_initialize(pmu->dev); ret = dev_set_name(pmu->dev, "%s", pmu->name); if (ret) @@ -5596,6 +5648,9 @@ got_cpu_context: pmu->pmu_disable = perf_pmu_nop_void; } + if (!pmu->event_idx) + pmu->event_idx = perf_event_idx_default; + list_add_rcu(&pmu->entry, &pmus); ret = 0; unlock: |