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perf/core: Add a new PERF_EV_CAP_SIBLING event capability

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Current perf assumes that events in a group are independent. Close an
event doesn't impact the value of the other events in the same group.
If the closed event is a member, after the event closure, other events
are still running like a group. If the closed event is a leader, other
events are running as singleton events.

Add PERF_EV_CAP_SIBLING to allow events to indicate they require being
part of a group, and when the leader dies they cannot exist
independently.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200723171117.9918-8-kan.liang@linux.intel.com
This commit is contained in:
Kan Liang
2020-07-23 10:11:10 -07:00
committed by Peter Zijlstra
parent 58da7dbe6f
commit 9f0c4fa111
2 changed files with 37 additions and 5 deletions
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4
include/linux/perf_event.h
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@@ -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)