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Commit 4ff6a8de authored by David Carrillo-Cisneros's avatar David Carrillo-Cisneros Committed by Ingo Molnar
Browse files

perf/core: Generalize event->group_flags 



Currently, PERF_GROUP_SOFTWARE is used in the group_flags field of a
group's leader to indicate that is_software_event(event) is true for all
events in a group. This is the only usage of event->group_flags.

This pattern of setting a group level flags when all events in the group
share a property is useful for the flag introduced in the next patch and
for future CQM/CMT flags. So this patches generalizes group_flags to work
as an aggregate of event level flags.

PERF_GROUP_SOFTWARE denotes an inmutable event's property. All other flags
that I intend to add are also determinable at event initialization.
To better convey the above, this patch renames event's group_flags to
group_caps and PERF_GROUP_SOFTWARE to PERF_EV_CAP_SOFTWARE.

Individual event flags are stored in the new event->event_caps. Since the
cap flags do not change after event initialization, there is no need to
serialize event_caps. This new field is used when events are added to a
context, similarly to how PERF_GROUP_SOFTWARE and is_software_event()
worked.

Lastly, for consistency, updates is_software_event() to rely in event_cap
instead of the context index.

Signed-off-by: default avatarDavid Carrillo-Cisneros <davidcc@google.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/1471467307-61171-3-git-send-email-davidcc@google.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 29dd3288

include/linux/perf_event.h

+13 −5
Original line number Diff line number Diff line
@@ -510,9 +510,12 @@ typedef void (*perf_overflow_handler_t)(struct perf_event *, 
					struct perf_sample_data *,

					struct pt_regs *regs);



enum perf_group_flag {

	PERF_GROUP_SOFTWARE		= 0x1,

};

/*

 * Event capabilities. For event_caps and groups caps.

 *

 * PERF_EV_CAP_SOFTWARE: Is a software event.

 */

#define PERF_EV_CAP_SOFTWARE		BIT(0)



#define SWEVENT_HLIST_BITS		8

#define SWEVENT_HLIST_SIZE		(1 << SWEVENT_HLIST_BITS)
@@ -568,7 +571,12 @@ struct perf_event { 
	struct hlist_node		hlist_entry;

	struct list_head		active_entry;

	int				nr_siblings;

	int				group_flags;



	/* Not serialized. Only written during event initialization. */

	int				event_caps;

	/* The cumulative AND of all event_caps for events in this group. */

	int				group_caps;



	struct perf_event		*group_leader;

	struct pmu			*pmu;

	void				*pmu_private;
@@ -988,7 +996,7 @@ static inline bool is_sampling_event(struct perf_event *event) 
 */

static inline int is_software_event(struct perf_event *event)

{

	return event->pmu->task_ctx_nr == perf_sw_context;

	return event->event_caps & PERF_EV_CAP_SOFTWARE;

}



extern struct static_key perf_swevent_enabled[PERF_COUNT_SW_MAX];

kernel/events/core.c

+8 −8
Original line number Diff line number Diff line
@@ -1475,8 +1475,7 @@ list_add_event(struct perf_event *event, struct perf_event_context *ctx) 
	if (event->group_leader == event) {

		struct list_head *list;



		if (is_software_event(event))

			event->group_flags |= PERF_GROUP_SOFTWARE;

		event->group_caps = event->event_caps;



		list = ctx_group_list(event, ctx);

		list_add_tail(&event->group_entry, list);
@@ -1630,9 +1629,7 @@ static void perf_group_attach(struct perf_event *event) 


	WARN_ON_ONCE(group_leader->ctx != event->ctx);



	if (group_leader->group_flags & PERF_GROUP_SOFTWARE &&

			!is_software_event(event))

		group_leader->group_flags &= ~PERF_GROUP_SOFTWARE;

	group_leader->group_caps &= event->event_caps;



	list_add_tail(&event->group_entry, &group_leader->sibling_list);

	group_leader->nr_siblings++;
@@ -1723,7 +1720,7 @@ static void perf_group_detach(struct perf_event *event) 
		sibling->group_leader = sibling;



		/* Inherit group flags from the previous leader */

		sibling->group_flags = event->group_flags;

		sibling->group_caps = event->group_caps;



		WARN_ON_ONCE(sibling->ctx != event->ctx);

	}
@@ -2149,7 +2146,7 @@ static int group_can_go_on(struct perf_event *event, 
	/*

	 * Groups consisting entirely of software events can always go on.

	 */

	if (event->group_flags & PERF_GROUP_SOFTWARE)

	if (event->group_caps & PERF_EV_CAP_SOFTWARE)

		return 1;

	/*

	 * If an exclusive group is already on, no other hardware
@@ -9490,6 +9487,9 @@ SYSCALL_DEFINE5(perf_event_open, 
			goto err_alloc;

	}



	if (pmu->task_ctx_nr == perf_sw_context)

		event->event_caps |= PERF_EV_CAP_SOFTWARE;



	if (group_leader &&

	    (is_software_event(event) != is_software_event(group_leader))) {

		if (is_software_event(event)) {
@@ -9503,7 +9503,7 @@ SYSCALL_DEFINE5(perf_event_open, 
			 */

			pmu = group_leader->pmu;

		} else if (is_software_event(group_leader) &&

			   (group_leader->group_flags & PERF_GROUP_SOFTWARE)) {

			   (group_leader->group_caps & PERF_EV_CAP_SOFTWARE)) {

			/*

			 * In case the group is a pure software group, and we

			 * try to add a hardware event, move the whole group to