From: Kan Liang <kan.li...@intel.com>
An earlier kernel patch allowed enabling PT and LBR at the same time on
Goldmont.
commit ccbebba4c6bf ("perf/x86/intel/pt: Bypass PT vs. LBR exclusivity
if the core supports it")
However, users still cannot use Intel PT and LBRs simultaneously.
$ sudo perf record -e cycles,intel_pt//u -b -- sleep 1
Error:
PMU Hardware doesn't support sampling/overflow-interrupts.
PT implicitly adds dummy event in perf tool. dummy event is software
event which doesn't support LBR.
Always setting no branch for dummy event in Intel PT.
Signed-off-by: Kan Liang <kan.li...@intel.com>
---
Changes since V1
- change the BRANCH_STACK sample bit directly (jirka)
tools/perf/arch/x86/util/intel-pt.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/tools/perf/arch/x86/util/intel-pt.c
b/tools/perf/arch/x86/util/intel-pt.c
index 4fe1aed..2201f3b 100644
--- a/tools/perf/arch/x86/util/intel-pt.c
+++ b/tools/perf/arch/x86/util/intel-pt.c
@@ -700,6 +700,7 @@ static int intel_pt_recording_options(struct
auxtrace_record *itr,
perf_evsel__set_sample_bit(switch_evsel, TID);
perf_evsel__set_sample_bit(switch_evsel, TIME);
perf_evsel__set_sample_bit(switch_evsel, CPU);
+ perf_evsel__reset_sample_bit(switch_evsel,
BRANCH_STACK);
opts->record_switch_events = false;
ptr->have_sched_switch = 3;
@@ -761,6 +762,7 @@ static int intel_pt_recording_options(struct
auxtrace_record *itr,
/* And the CPU for switch events */
perf_evsel__set_sample_bit(tracking_evsel, CPU);
}
+ perf_evsel__reset_sample_bit(tracking_evsel, BRANCH_STACK);
}
/*
--
2.9.4
