perf/x86: Add PERF_X86_EVENT_NEEDS_BRANCH_STACK flag

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Currently, branch_sample_type !=0 is used to check whether a branch
stack setup is required. But it doesn't check the sample type,
unnecessary branch stack setup may be done for a counting event. E.g.,
perf record -e "{branch-instructions,branch-misses}:S" -j any
Also, the event only with the new PERF_SAMPLE_BRANCH_COUNTERS branch
sample type may not require a branch stack setup either.

Add a new flag NEEDS_BRANCH_STACK to indicate whether the event requires
a branch stack setup. Replace the needs_branch_stack() by checking the
new flag.

The counting event check is implemented here. The later patch will take
the new PERF_SAMPLE_BRANCH_COUNTERS into account.

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/20231025201626.3000228-2-kan.liang@linux.intel.com

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This commit is contained in:

Kan Liang 2023-10-25 13:16:20 -07:00 • committed by Peter Zijlstra

parent 571d91dcad

commit 85846b2707

2 changed files with 12 additions and 3 deletions

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14

arch/x86/events/intel/core.c

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1

arch/x86/events/perf_event_flags.h

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