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perf/core: Generalize event->group_flags

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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: David Carrillo-Cisneros <davidcc@google.com>
Signed-off-by: Peter 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: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
David Carrillo-Cisneros 2016-08-17 13:55:05 -07:00 committed by Ingo Molnar
parent 29dd328870
commit 4ff6a8debf
2 changed files with 21 additions and 13 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

18
include/linux/perf_event.h
View file

@ -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];

16
kernel/events/core.c
View file

@ -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