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Subject[PATCH] perf tools: set no branch type for dummy event in PT
Date
From: Kan Liang <kan.liang@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 branch_type=no for dummy event in Intel PT.

Signed-off-by: Kan Liang <kan.liang@intel.com>
---
tools/perf/arch/x86/util/intel-pt.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)

diff --git a/tools/perf/arch/x86/util/intel-pt.c b/tools/perf/arch/x86/util/intel-pt.c
index f630de0..651ab9e 100644
--- a/tools/perf/arch/x86/util/intel-pt.c
+++ b/tools/perf/arch/x86/util/intel-pt.c
@@ -544,6 +544,22 @@ static int intel_pt_validate_config(struct perf_pmu *intel_pt_pmu,
evsel->attr.config);
}

+static int add_no_lbr_config_term(struct list_head *config_terms)
+{
+ struct perf_evsel_config_term *lbr_term;
+
+ lbr_term = zalloc(sizeof(*lbr_term));
+ if (!lbr_term)
+ return -ENOMEM;
+
+ INIT_LIST_HEAD(&lbr_term->list);
+ lbr_term->type = PERF_EVSEL__CONFIG_TERM_BRANCH;
+ lbr_term->val.branch = strdup("no");
+ list_add_tail(&lbr_term->list, config_terms);
+
+ return 0;
+}
+
static int intel_pt_recording_options(struct auxtrace_record *itr,
struct perf_evlist *evlist,
struct record_opts *opts)
@@ -701,6 +717,8 @@ static int intel_pt_recording_options(struct auxtrace_record *itr,
perf_evsel__set_sample_bit(switch_evsel, TIME);
perf_evsel__set_sample_bit(switch_evsel, CPU);

+ add_no_lbr_config_term(&switch_evsel->config_terms);
+
opts->record_switch_events = false;
ptr->have_sched_switch = 3;
} else {
@@ -760,6 +778,7 @@ static int intel_pt_recording_options(struct auxtrace_record *itr,
/* And the CPU for switch events */
perf_evsel__set_sample_bit(tracking_evsel, CPU);
}
+ add_no_lbr_config_term(&tracking_evsel->config_terms);
}

/*
--
2.9.4
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