perf/core: Add a new PERF_EV_CAP_SIBLING event capability (9f0c4fa1) · Commits · 戴 / test

include/linux/perf_event.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -576,9 +576,13 @@ typedef void (perf_overflow_handler_t)(struct perf_event ,
		* PERF_EV_CAP_SOFTWARE: Is a software event.
		* PERF_EV_CAP_READ_ACTIVE_PKG: A CPU event (or cgroup event) that can be read
		* from any CPU in the package where it is active.
		* PERF_EV_CAP_SIBLING: An event with this flag must be a group sibling and
		* cannot be a group leader. If an event with this flag is detached from the
		* group it is scheduled out and moved into an unrecoverable ERROR state.
		*/
		#define PERF_EV_CAP_SOFTWARE BIT(0)
		#define PERF_EV_CAP_READ_ACTIVE_PKG BIT(1)
		#define PERF_EV_CAP_SIBLING BIT(2)

		#define SWEVENT_HLIST_BITS 8
		#define SWEVENT_HLIST_SIZE (1 << SWEVENT_HLIST_BITS)

kernel/events/core.c

+33 −5

Original line number	Diff line number	Diff line
		@@ -2133,8 +2133,24 @@ static inline struct list_head get_event_list(struct perf_event event)
		return event->attr.pinned ? &ctx->pinned_active : &ctx->flexible_active;
		}

		/*
		* Events that have PERF_EV_CAP_SIBLING require being part of a group and
		* cannot exist on their own, schedule them out and move them into the ERROR
		* state. Also see _perf_event_enable(), it will not be able to recover
		* this ERROR state.
		*/
		static inline void perf_remove_sibling_event(struct perf_event *event)
		{
		struct perf_event_context *ctx = event->ctx;
		struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);

		event_sched_out(event, cpuctx, ctx);
		perf_event_set_state(event, PERF_EVENT_STATE_ERROR);
		}

		static void perf_group_detach(struct perf_event *event)
		{
		struct perf_event *leader = event->group_leader;
		struct perf_event sibling, tmp;
		struct perf_event_context *ctx = event->ctx;

		@@ -2153,7 +2169,7 @@ static void perf_group_detach(struct perf_event *event)
		/*
		* If this is a sibling, remove it from its group.
		*/
		if (event->group_leader != event) {
		if (leader != event) {
		list_del_init(&event->sibling_list);
		event->group_leader->nr_siblings--;
		goto out;
		@@ -2166,6 +2182,9 @@ static void perf_group_detach(struct perf_event *event)
		*/
		list_for_each_entry_safe(sibling, tmp, &event->sibling_list, sibling_list) {

		if (sibling->event_caps & PERF_EV_CAP_SIBLING)
		perf_remove_sibling_event(sibling);

		sibling->group_leader = sibling;
		list_del_init(&sibling->sibling_list);

		@@ -2183,10 +2202,10 @@ static void perf_group_detach(struct perf_event *event)
		}

		out:
		perf_event__header_size(event->group_leader);

		for_each_sibling_event(tmp, event->group_leader)
		for_each_sibling_event(tmp, leader)
		perf_event__header_size(tmp);

		perf_event__header_size(leader);
		}

		static bool is_orphaned_event(struct perf_event *event)
		@@ -2979,6 +2998,7 @@ static void _perf_event_enable(struct perf_event *event)
		raw_spin_lock_irq(&ctx->lock);
		if (event->state >= PERF_EVENT_STATE_INACTIVE \|\|
		event->state < PERF_EVENT_STATE_ERROR) {
		out:
		raw_spin_unlock_irq(&ctx->lock);
		return;
		}
		@@ -2990,8 +3010,16 @@ static void _perf_event_enable(struct perf_event *event)
		* has gone back into error state, as distinct from the task having
		* been scheduled away before the cross-call arrived.
		*/
		if (event->state == PERF_EVENT_STATE_ERROR)
		if (event->state == PERF_EVENT_STATE_ERROR) {
		/*
		* Detached SIBLING events cannot leave ERROR state.
		*/
		if (event->event_caps & PERF_EV_CAP_SIBLING &&
		event->group_leader == event)
		goto out;

		event->state = PERF_EVENT_STATE_OFF;
		}
		raw_spin_unlock_irq(&ctx->lock);

		event_function_call(event, __perf_event_enable, NULL);

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