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perf evlist: Save branch counters information

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The branch counters logging (A.K.A LBR event logging) introduces a
per-counter indication of precise event occurrences in LBRs. The kernel
only dumps the number of occurrences into a record. The perf tool has
to map the number to the corresponding event.

Add evlist__update_br_cntr() to go through the evlist to pick the
events that are configured to be logged. Assign a logical idx to track
them, and add the total number of the events in the leader event.

The total number will be used to allocate the space to save the branch
counters for a block. The logical idx will be used to locate the
corresponding event quickly in the following patches.

It only needs to iterate the evlist once. The
evsel__has_branch_counters() is also optimized.

Reviewed-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lore.kernel.org/r/20240813160208.2493643-4-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Kan Liang 2024-08-13 09:02:02 -07:00 committed by Arnaldo Carvalho de Melo
parent 183212a45e
commit 3a867a6dad
4 changed files with 32 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
tools/perf/util/evlist.c
View File

@ -79,6 +79,7 @@ void evlist__init(struct evlist *evlist, struct perf_cpu_map *cpus,
evlist->ctl_fd.fd = -1;
evlist->ctl_fd.ack = -1;
evlist->ctl_fd.pos = -1;
evlist->nr_br_cntr = -1;
}
struct evlist *evlist__new(void)
@ -1264,6 +1265,20 @@ u64 evlist__combined_branch_type(struct evlist *evlist)
return branch_type;
}
void evlist__update_br_cntr(struct evlist *evlist)
{
struct evsel *evsel;
int i = 0;
evlist__for_each_entry(evlist, evsel) {
if (evsel->core.attr.branch_sample_type & PERF_SAMPLE_BRANCH_COUNTERS) {
evsel->br_cntr_idx = i++;
evsel__leader(evsel)->br_cntr_nr++;
}
}
evlist->nr_br_cntr = i;
}
bool evlist__valid_read_format(struct evlist *evlist)
{
struct evsel *first = evlist__first(evlist), *pos = first;

2
tools/perf/util/evlist.h
View File

@ -57,6 +57,7 @@ struct evlist {
bool enabled;
int id_pos;
int is_pos;
int nr_br_cntr;
u64 combined_sample_type;
enum bkw_mmap_state bkw_mmap_state;
struct {
@ -219,6 +220,7 @@ int evlist__apply_filters(struct evlist *evlist, struct evsel **err_evsel,
u64 __evlist__combined_sample_type(struct evlist *evlist);
u64 evlist__combined_sample_type(struct evlist *evlist);
u64 evlist__combined_branch_type(struct evlist *evlist);
void evlist__update_br_cntr(struct evlist *evlist);
bool evlist__sample_id_all(struct evlist *evlist);
u16 evlist__id_hdr_size(struct evlist *evlist);

13
tools/perf/util/evsel.c
View File

@ -2636,17 +2636,18 @@ u64 evsel__bitfield_swap_branch_flags(u64 value)
static inline bool evsel__has_branch_counters(const struct evsel *evsel)
{
struct evsel *cur, *leader = evsel__leader(evsel);
struct evsel *leader = evsel__leader(evsel);
/* The branch counters feature only supports group */
if (!leader || !evsel->evlist)
return false;
evlist__for_each_entry(evsel->evlist, cur) {
if ((leader == evsel__leader(cur)) &&
(cur->core.attr.branch_sample_type & PERF_SAMPLE_BRANCH_COUNTERS))
return true;
}
if (evsel->evlist->nr_br_cntr < 0)
evlist__update_br_cntr(evsel->evlist);
if (leader->br_cntr_nr > 0)
return true;
return false;
}

8
tools/perf/util/evsel.h
View File

@ -148,6 +148,14 @@ struct evsel {
*/
__u64 synth_sample_type;
/*
* Store the branch counter related information.
* br_cntr_idx: The idx of the branch counter event in the evlist
* br_cntr_nr: The number of the branch counter event in the group
* (Only available for the leader event)
*/
int br_cntr_idx;
int br_cntr_nr;
/*
* bpf_counter_ops serves two use cases:
* 1. perf-stat -b counting events used byBPF programs