Subject: perf: Add group reads to perf_event_read() From: Peter Zijlstra Date: Thu, 23 Jul 2015 10:04:35 +0200 Enable perf_event_read() to update entire groups at once, this will be useful for read transactions. Cc: Ingo Molnar Cc: Arnaldo Carvalho de Melo Cc: Michael Ellerman Cc: Sukadev Bhattiprolu Signed-off-by: Peter Zijlstra (Intel) Link: http://lkml.kernel.org/r/20150723080435.GE25159@twins.programming.kicks-ass.net --- kernel/events/core.c | 39 ++++++++++++++++++++++++++++++++------- 1 file changed, 32 insertions(+), 7 deletions(-) --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3184,12 +3184,18 @@ void perf_event_exec(void) rcu_read_unlock(); } +struct perf_read_data { + struct perf_event *event; + bool group; +}; + /* * Cross CPU call to read the hardware event */ static void __perf_event_read(void *info) { - struct perf_event *event = info; + struct perf_read_data *data = info; + struct perf_event *sub, *event = data->event; struct perf_event_context *ctx = event->ctx; struct perf_cpu_context *cpuctx = __get_cpu_context(ctx); @@ -3208,9 +3214,21 @@ static void __perf_event_read(void *info update_context_time(ctx); update_cgrp_time_from_event(event); } + update_event_times(event); if (event->state == PERF_EVENT_STATE_ACTIVE) event->pmu->read(event); + + if (!data->group) + goto unlock; + + list_for_each_entry(sub, &event->sibling_list, group_entry) { + update_event_times(sub); + if (sub->state == PERF_EVENT_STATE_ACTIVE) + sub->pmu->read(sub); + } + +unlock: raw_spin_unlock(&ctx->lock); } @@ -3222,15 +3240,19 @@ static inline u64 perf_event_count(struc return __perf_event_count(event); } -static void perf_event_read(struct perf_event *event) +static void perf_event_read(struct perf_event *event, bool group) { /* * If event is enabled and currently active on a CPU, update the * value in the event structure: */ if (event->state == PERF_EVENT_STATE_ACTIVE) { + struct perf_read_data data = { + .event = event, + .group = group, + }; smp_call_function_single(event->oncpu, - __perf_event_read, event, 1); + __perf_event_read, &data, 1); } else if (event->state == PERF_EVENT_STATE_INACTIVE) { struct perf_event_context *ctx = event->ctx; unsigned long flags; @@ -3245,7 +3267,10 @@ static void perf_event_read(struct perf_ update_context_time(ctx); update_cgrp_time_from_event(event); } - update_event_times(event); + if (group) + update_group_times(event); + else + update_event_times(event); raw_spin_unlock_irqrestore(&ctx->lock, flags); } } @@ -3764,7 +3789,7 @@ u64 perf_event_read_value(struct perf_ev mutex_lock(&event->child_mutex); - perf_event_read(event); + perf_event_read(event, false); total += perf_event_count(event); *enabled += event->total_time_enabled + @@ -3773,7 +3798,7 @@ u64 perf_event_read_value(struct perf_ev atomic64_read(&event->child_total_time_running); list_for_each_entry(child, &event->child_list, child_list) { - perf_event_read(child); + perf_event_read(child, false); total += perf_event_count(child); *enabled += child->total_time_enabled; *running += child->total_time_running; @@ -3934,7 +3959,7 @@ static unsigned int perf_poll(struct fil static void _perf_event_reset(struct perf_event *event) { - perf_event_read(event); + perf_event_read(event, false); local64_set(&event->count, 0); perf_event_update_userpage(event); }