diff options
| -rw-r--r-- | include/linux/perf_event.h | 19 | ||||
| -rw-r--r-- | kernel/events/core.c | 385 |
2 files changed, 130 insertions, 274 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index b7532650de47..874b71a70058 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -588,26 +588,10 @@ struct perf_event { * has been enabled (i.e. eligible to run, and the task has * been scheduled in, if this is a per-task event) * and running (scheduled onto the CPU), respectively. - * - * They are computed from tstamp_enabled, tstamp_running and - * tstamp_stopped when the event is in INACTIVE or ACTIVE state. */ u64 total_time_enabled; u64 total_time_running; - - /* - * These are timestamps used for computing total_time_enabled - * and total_time_running when the event is in INACTIVE or - * ACTIVE state, measured in nanoseconds from an arbitrary point - * in time. - * tstamp_enabled: the notional time when the event was enabled - * tstamp_running: the notional time when the event was scheduled on - * tstamp_stopped: in INACTIVE state, the notional time when the - * event was scheduled off. - */ - u64 tstamp_enabled; - u64 tstamp_running; - u64 tstamp_stopped; + u64 tstamp; /* * timestamp shadows the actual context timing but it can @@ -699,7 +683,6 @@ struct perf_event { #ifdef CONFIG_CGROUP_PERF struct perf_cgroup *cgrp; /* cgroup event is attach to */ - int cgrp_defer_enabled; #endif struct list_head sb_list; diff --git a/kernel/events/core.c b/kernel/events/core.c index 6f74f9c35490..2551e8ce7224 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -582,6 +582,88 @@ static inline u64 perf_event_clock(struct perf_event *event) return event->clock(); } +/* + * State based event timekeeping... + * + * The basic idea is to use event->state to determine which (if any) time + * fields to increment with the current delta. This means we only need to + * update timestamps when we change state or when they are explicitly requested + * (read). + * + * Event groups make things a little more complicated, but not terribly so. The + * rules for a group are that if the group leader is OFF the entire group is + * OFF, irrespecive of what the group member states are. This results in + * __perf_effective_state(). + * + * A futher ramification is that when a group leader flips between OFF and + * !OFF, we need to update all group member times. + * + * + * NOTE: perf_event_time() is based on the (cgroup) context time, and thus we + * need to make sure the relevant context time is updated before we try and + * update our timestamps. + */ + +static __always_inline enum perf_event_state +__perf_effective_state(struct perf_event *event) +{ + struct perf_event *leader = event->group_leader; + + if (leader->state <= PERF_EVENT_STATE_OFF) + return leader->state; + + return event->state; +} + +static __always_inline void +__perf_update_times(struct perf_event *event, u64 now, u64 *enabled, u64 *running) +{ + enum perf_event_state state = __perf_effective_state(event); + u64 delta = now - event->tstamp; + + *enabled = event->total_time_enabled; + if (state >= PERF_EVENT_STATE_INACTIVE) + *enabled += delta; + + *running = event->total_time_running; + if (state >= PERF_EVENT_STATE_ACTIVE) + *running += delta; +} + +static void perf_event_update_time(struct perf_event *event) +{ + u64 now = perf_event_time(event); + + __perf_update_times(event, now, &event->total_time_enabled, + &event->total_time_running); + event->tstamp = now; +} + +static void perf_event_update_sibling_time(struct perf_event *leader) +{ + struct perf_event *sibling; + + list_for_each_entry(sibling, &leader->sibling_list, group_entry) + perf_event_update_time(sibling); +} + +static void +perf_event_set_state(struct perf_event *event, enum perf_event_state state) +{ + if (event->state == state) + return; + + perf_event_update_time(event); + /* + * If a group leader gets enabled/disabled all its siblings + * are affected too. + */ + if ((event->state < 0) ^ (state < 0)) + perf_event_update_sibling_time(event); + + WRITE_ONCE(event->state, state); +} + #ifdef CONFIG_CGROUP_PERF static inline bool @@ -841,40 +923,6 @@ perf_cgroup_set_shadow_time(struct perf_event *event, u64 now) event->shadow_ctx_time = now - t->timestamp; } -static inline void -perf_cgroup_defer_enabled(struct perf_event *event) -{ - /* - * when the current task's perf cgroup does not match - * the event's, we need to remember to call the - * perf_mark_enable() function the first time a task with - * a matching perf cgroup is scheduled in. - */ - if (is_cgroup_event(event) && !perf_cgroup_match(event)) - event->cgrp_defer_enabled = 1; -} - -static inline void -perf_cgroup_mark_enabled(struct perf_event *event, - struct perf_event_context *ctx) -{ - struct perf_event *sub; - u64 tstamp = perf_event_time(event); - - if (!event->cgrp_defer_enabled) - return; - - event->cgrp_defer_enabled = 0; - - event->tstamp_enabled = tstamp - event->total_time_enabled; - list_for_each_entry(sub, &event->sibling_list, group_entry) { - if (sub->state >= PERF_EVENT_STATE_INACTIVE) { - sub->tstamp_enabled = tstamp - sub->total_time_enabled; - sub->cgrp_defer_enabled = 0; - } - } -} - /* * Update cpuctx->cgrp so that it is set when first cgroup event is added and * cleared when last cgroup event is removed. @@ -973,17 +1021,6 @@ static inline u64 perf_cgroup_event_time(struct perf_event *event) } static inline void -perf_cgroup_defer_enabled(struct perf_event *event) -{ -} - -static inline void -perf_cgroup_mark_enabled(struct perf_event *event, - struct perf_event_context *ctx) -{ -} - -static inline void list_update_cgroup_event(struct perf_event *event, struct perf_event_context *ctx, bool add) { @@ -1396,60 +1433,6 @@ static u64 perf_event_time(struct perf_event *event) return ctx ? ctx->time : 0; } -/* - * Update the total_time_enabled and total_time_running fields for a event. - */ -static void update_event_times(struct perf_event *event) -{ - struct perf_event_context *ctx = event->ctx; - u64 run_end; - - lockdep_assert_held(&ctx->lock); - - if (event->state < PERF_EVENT_STATE_INACTIVE || - event->group_leader->state < PERF_EVENT_STATE_INACTIVE) - return; - - /* - * in cgroup mode, time_enabled represents - * the time the event was enabled AND active - * tasks were in the monitored cgroup. This is - * independent of the activity of the context as - * there may be a mix of cgroup and non-cgroup events. - * - * That is why we treat cgroup events differently - * here. - */ - if (is_cgroup_event(event)) - run_end = perf_cgroup_event_time(event); - else if (ctx->is_active) - run_end = ctx->time; - else - run_end = event->tstamp_stopped; - - event->total_time_enabled = run_end - event->tstamp_enabled; - - if (event->state == PERF_EVENT_STATE_INACTIVE) - run_end = event->tstamp_stopped; - else - run_end = perf_event_time(event); - - event->total_time_running = run_end - event->tstamp_running; - -} - -/* - * Update total_time_enabled and total_time_running for all events in a group. - */ -static void update_group_times(struct perf_event *leader) -{ - struct perf_event *event; - - update_event_times(leader); - list_for_each_entry(event, &leader->sibling_list, group_entry) - update_event_times(event); -} - static enum event_type_t get_event_type(struct perf_event *event) { struct perf_event_context *ctx = event->ctx; @@ -1492,6 +1475,8 @@ list_add_event(struct perf_event *event, struct perf_event_context *ctx) WARN_ON_ONCE(event->attach_state & PERF_ATTACH_CONTEXT); event->attach_state |= PERF_ATTACH_CONTEXT; + event->tstamp = perf_event_time(event); + /* * If we're a stand alone event or group leader, we go to the context * list, group events are kept attached to the group so that @@ -1699,8 +1684,6 @@ list_del_event(struct perf_event *event, struct perf_event_context *ctx) if (event->group_leader == event) list_del_init(&event->group_entry); - update_group_times(event); - /* * If event was in error state, then keep it * that way, otherwise bogus counts will be @@ -1709,7 +1692,7 @@ list_del_event(struct perf_event *event, struct perf_event_context *ctx) * of the event */ if (event->state > PERF_EVENT_STATE_OFF) - event->state = PERF_EVENT_STATE_OFF; + perf_event_set_state(event, PERF_EVENT_STATE_OFF); ctx->generation++; } @@ -1808,38 +1791,24 @@ event_sched_out(struct perf_event *event, struct perf_cpu_context *cpuctx, struct perf_event_context *ctx) { - u64 tstamp = perf_event_time(event); - u64 delta; + enum perf_event_state state = PERF_EVENT_STATE_INACTIVE; WARN_ON_ONCE(event->ctx != ctx); lockdep_assert_held(&ctx->lock); - /* - * An event which could not be activated because of - * filter mismatch still needs to have its timings - * maintained, otherwise bogus information is return - * via read() for time_enabled, time_running: - */ - if (event->state == PERF_EVENT_STATE_INACTIVE && - !event_filter_match(event)) { - delta = tstamp - event->tstamp_stopped; - event->tstamp_running += delta; - event->tstamp_stopped = tstamp; - } - if (event->state != PERF_EVENT_STATE_ACTIVE) return; perf_pmu_disable(event->pmu); - event->tstamp_stopped = tstamp; event->pmu->del(event, 0); event->oncpu = -1; - event->state = PERF_EVENT_STATE_INACTIVE; + if (event->pending_disable) { event->pending_disable = 0; - event->state = PERF_EVENT_STATE_OFF; + state = PERF_EVENT_STATE_OFF; } + perf_event_set_state(event, state); if (!is_software_event(event)) cpuctx->active_oncpu--; @@ -1859,7 +1828,9 @@ group_sched_out(struct perf_event *group_event, struct perf_event_context *ctx) { struct perf_event *event; - int state = group_event->state; + + if (group_event->state != PERF_EVENT_STATE_ACTIVE) + return; perf_pmu_disable(ctx->pmu); @@ -1873,7 +1844,7 @@ group_sched_out(struct perf_event *group_event, perf_pmu_enable(ctx->pmu); - if (state == PERF_EVENT_STATE_ACTIVE && group_event->attr.exclusive) + if (group_event->attr.exclusive) cpuctx->exclusive = 0; } @@ -1965,12 +1936,12 @@ static void __perf_event_disable(struct perf_event *event, update_cgrp_time_from_event(event); } - update_group_times(event); if (event == event->group_leader) group_sched_out(event, cpuctx, ctx); else event_sched_out(event, cpuctx, ctx); - event->state = PERF_EVENT_STATE_OFF; + + perf_event_set_state(event, PERF_EVENT_STATE_OFF); } /* @@ -2027,8 +1998,7 @@ void perf_event_disable_inatomic(struct perf_event *event) } static void perf_set_shadow_time(struct perf_event *event, - struct perf_event_context *ctx, - u64 tstamp) + struct perf_event_context *ctx) { /* * use the correct time source for the time snapshot @@ -2056,9 +2026,9 @@ static void perf_set_shadow_time(struct perf_event *event, * is cleaner and simpler to understand. */ if (is_cgroup_event(event)) - perf_cgroup_set_shadow_time(event, tstamp); + perf_cgroup_set_shadow_time(event, event->tstamp); else - event->shadow_ctx_time = tstamp - ctx->timestamp; + event->shadow_ctx_time = event->tstamp - ctx->timestamp; } #define MAX_INTERRUPTS (~0ULL) @@ -2071,7 +2041,6 @@ event_sched_in(struct perf_event *event, struct perf_cpu_context *cpuctx, struct perf_event_context *ctx) { - u64 tstamp = perf_event_time(event); int ret = 0; lockdep_assert_held(&ctx->lock); @@ -2086,7 +2055,7 @@ event_sched_in(struct perf_event *event, * ->oncpu if it sees ACTIVE. */ smp_wmb(); - WRITE_ONCE(event->state, PERF_EVENT_STATE_ACTIVE); + perf_event_set_state(event, PERF_EVENT_STATE_ACTIVE); /* * Unthrottle events, since we scheduled we might have missed several @@ -2100,19 +2069,17 @@ event_sched_in(struct perf_event *event, perf_pmu_disable(event->pmu); - perf_set_shadow_time(event, ctx, tstamp); + perf_set_shadow_time(event, ctx); perf_log_itrace_start(event); if (event->pmu->add(event, PERF_EF_START)) { - event->state = PERF_EVENT_STATE_INACTIVE; + perf_event_set_state(event, PERF_EVENT_STATE_INACTIVE); event->oncpu = -1; ret = -EAGAIN; goto out; } - event->tstamp_running += tstamp - event->tstamp_stopped; - if (!is_software_event(event)) cpuctx->active_oncpu++; if (!ctx->nr_active++) @@ -2136,8 +2103,6 @@ group_sched_in(struct perf_event *group_event, { struct perf_event *event, *partial_group = NULL; struct pmu *pmu = ctx->pmu; - u64 now = ctx->time; - bool simulate = false; if (group_event->state == PERF_EVENT_STATE_OFF) return 0; @@ -2167,27 +2132,13 @@ group_error: /* * Groups can be scheduled in as one unit only, so undo any * partial group before returning: - * The events up to the failed event are scheduled out normally, - * tstamp_stopped will be updated. - * - * The failed events and the remaining siblings need to have - * their timings updated as if they had gone thru event_sched_in() - * and event_sched_out(). This is required to get consistent timings - * across the group. This also takes care of the case where the group - * could never be scheduled by ensuring tstamp_stopped is set to mark - * the time the event was actually stopped, such that time delta - * calculation in update_event_times() is correct. + * The events up to the failed event are scheduled out normally. */ list_for_each_entry(event, &group_event->sibling_list, group_entry) { if (event == partial_group) - simulate = true; + break; - if (simulate) { - event->tstamp_running += now - event->tstamp_stopped; - event->tstamp_stopped = now; - } else { - event_sched_out(event, cpuctx, ctx); - } + event_sched_out(event, cpuctx, ctx); } event_sched_out(group_event, cpuctx, ctx); @@ -2229,46 +2180,11 @@ static int group_can_go_on(struct perf_event *event, return can_add_hw; } -/* - * Complement to update_event_times(). This computes the tstamp_* values to - * continue 'enabled' state from @now, and effectively discards the time - * between the prior tstamp_stopped and now (as we were in the OFF state, or - * just switched (context) time base). - * - * This further assumes '@event->state == INACTIVE' (we just came from OFF) and - * cannot have been scheduled in yet. And going into INACTIVE state means - * '@event->tstamp_stopped = @now'. - * - * Thus given the rules of update_event_times(): - * - * total_time_enabled = tstamp_stopped - tstamp_enabled - * total_time_running = tstamp_stopped - tstamp_running - * - * We can insert 'tstamp_stopped == now' and reverse them to compute new - * tstamp_* values. - */ -static void __perf_event_enable_time(struct perf_event *event, u64 now) -{ - WARN_ON_ONCE(event->state != PERF_EVENT_STATE_INACTIVE); - - event->tstamp_stopped = now; - event->tstamp_enabled = now - event->total_time_enabled; - event->tstamp_running = now - event->total_time_running; -} - static void add_event_to_ctx(struct perf_event *event, struct perf_event_context *ctx) { - u64 tstamp = perf_event_time(event); - list_add_event(event, ctx); perf_group_attach(event); - /* - * We can be called with event->state == STATE_OFF when we create with - * .disabled = 1. In that case the IOC_ENABLE will call this function. - */ - if (event->state == PERF_EVENT_STATE_INACTIVE) - __perf_event_enable_time(event, tstamp); } static void ctx_sched_out(struct perf_event_context *ctx, @@ -2500,28 +2416,6 @@ again: } /* - * Put a event into inactive state and update time fields. - * Enabling the leader of a group effectively enables all - * the group members that aren't explicitly disabled, so we - * have to update their ->tstamp_enabled also. - * Note: this works for group members as well as group leaders - * since the non-leader members' sibling_lists will be empty. - */ -static void __perf_event_mark_enabled(struct perf_event *event) -{ - struct perf_event *sub; - u64 tstamp = perf_event_time(event); - - event->state = PERF_EVENT_STATE_INACTIVE; - __perf_event_enable_time(event, tstamp); - list_for_each_entry(sub, &event->sibling_list, group_entry) { - /* XXX should not be > INACTIVE if event isn't */ - if (sub->state >= PERF_EVENT_STATE_INACTIVE) - __perf_event_enable_time(sub, tstamp); - } -} - -/* * Cross CPU call to enable a performance event */ static void __perf_event_enable(struct perf_event *event, @@ -2539,14 +2433,12 @@ static void __perf_event_enable(struct perf_event *event, if (ctx->is_active) ctx_sched_out(ctx, cpuctx, EVENT_TIME); - __perf_event_mark_enabled(event); + perf_event_set_state(event, PERF_EVENT_STATE_INACTIVE); if (!ctx->is_active) return; if (!event_filter_match(event)) { - if (is_cgroup_event(event)) - perf_cgroup_defer_enabled(event); ctx_sched_in(ctx, cpuctx, EVENT_TIME, current); return; } @@ -2866,18 +2758,10 @@ static void __perf_event_sync_stat(struct perf_event *event, * we know the event must be on the current CPU, therefore we * don't need to use it. */ - switch (event->state) { - case PERF_EVENT_STATE_ACTIVE: + if (event->state == PERF_EVENT_STATE_ACTIVE) event->pmu->read(event); - /* fall-through */ - case PERF_EVENT_STATE_INACTIVE: - update_event_times(event); - break; - - default: - break; - } + perf_event_update_time(event); /* * In order to keep per-task stats reliable we need to flip the event @@ -3114,10 +2998,6 @@ ctx_pinned_sched_in(struct perf_event_context *ctx, if (!event_filter_match(event)) continue; - /* may need to reset tstamp_enabled */ - if (is_cgroup_event(event)) - perf_cgroup_mark_enabled(event, ctx); - if (group_can_go_on(event, cpuctx, 1)) group_sched_in(event, cpuctx, ctx); @@ -3125,10 +3005,8 @@ ctx_pinned_sched_in(struct perf_event_context *ctx, * If this pinned group hasn't been scheduled, * put it in error state. */ - if (event->state == PERF_EVENT_STATE_INACTIVE) { - update_group_times(event); - event->state = PERF_EVENT_STATE_ERROR; - } + if (event->state == PERF_EVENT_STATE_INACTIVE) + perf_event_set_state(event, PERF_EVENT_STATE_ERROR); } } @@ -3150,10 +3028,6 @@ ctx_flexible_sched_in(struct perf_event_context *ctx, if (!event_filter_match(event)) continue; - /* may need to reset tstamp_enabled */ - if (is_cgroup_event(event)) - perf_cgroup_mark_enabled(event, ctx); - if (group_can_go_on(event, cpuctx, can_add_hw)) { if (group_sched_in(event, cpuctx, ctx)) can_add_hw = 0; @@ -3545,7 +3419,7 @@ static int event_enable_on_exec(struct perf_event *event, if (event->state >= PERF_EVENT_STATE_INACTIVE) return 0; - __perf_event_mark_enabled(event); + perf_event_set_state(event, PERF_EVENT_STATE_INACTIVE); return 1; } @@ -3644,10 +3518,9 @@ static void __perf_event_read(void *info) update_cgrp_time_from_event(event); } - if (!data->group) - update_event_times(event); - else - update_group_times(event); + perf_event_update_time(event); + if (data->group) + perf_event_update_sibling_time(event); if (event->state != PERF_EVENT_STATE_ACTIVE) goto unlock; @@ -3696,7 +3569,6 @@ int perf_event_read_local(struct perf_event *event, u64 *value, { unsigned long flags; int ret = 0; - u64 now; /* * Disabling interrupts avoids all counter scheduling (context @@ -3727,23 +3599,26 @@ int perf_event_read_local(struct perf_event *event, u64 *value, goto out; } - now = event->shadow_ctx_time + perf_clock(); - if (enabled) - *enabled = now - event->tstamp_enabled; + /* * If the event is currently on this CPU, its either a per-task event, * or local to this CPU. Furthermore it means its ACTIVE (otherwise * oncpu == -1). */ - if (event->oncpu == smp_processor_id()) { + if (event->oncpu == smp_processor_id()) event->pmu->read(event); - if (running) - *running = now - event->tstamp_running; - } else if (running) { - *running = event->total_time_running; - } *value = local64_read(&event->count); + if (enabled || running) { + u64 now = event->shadow_ctx_time + perf_clock(); + u64 __enabled, __running; + + __perf_update_times(event, now, &__enabled, &__running); + if (enabled) + *enabled = __enabled; + if (running) + *running = __running; + } out: local_irq_restore(flags); @@ -3818,10 +3693,9 @@ again: update_cgrp_time_from_event(event); } + perf_event_update_time(event); if (group) - update_group_times(event); - else - update_event_times(event); + perf_event_update_sibling_time(event); raw_spin_unlock_irqrestore(&ctx->lock, flags); } @@ -4945,8 +4819,7 @@ static void calc_timer_values(struct perf_event *event, *now = perf_clock(); ctx_time = event->shadow_ctx_time + *now; - *enabled = ctx_time - event->tstamp_enabled; - *running = ctx_time - event->tstamp_running; + __perf_update_times(event, ctx_time, enabled, running); } static void perf_event_init_userpage(struct perf_event *event) @@ -10581,7 +10454,7 @@ perf_event_exit_event(struct perf_event *child_event, if (parent_event) perf_group_detach(child_event); list_del_event(child_event, child_ctx); - child_event->state = PERF_EVENT_STATE_EXIT; /* is_event_hup() */ + perf_event_set_state(child_event, PERF_EVENT_STATE_EXIT); /* is_event_hup() */ raw_spin_unlock_irq(&child_ctx->lock); /* |