[PATCH v3 3/4] perf-stat: introduce config stat.bpf-counter-events

Song Liu
2021-04-16T22:13:58Z

Currently, to use BPF to aggregate perf event counters, the user uses
--bpf-counters option. Enable "use bpf by default" events with a config
option, stat.bpf-counter-events. Events with name in the option will use
BPF.

This also enables mixed BPF event and regular event in the same sesssion.
For example:

perf config stat.bpf-counter-events=instructions
perf stat -e instructions,cs

The second command will use BPF for "instructions" but not "cs".

Signed-off-by: Song Liu <song@kernel.org>
---
tools/perf/Documentation/perf-stat.txt | 2 ++
tools/perf/builtin-stat.c | 43 +++++++++++++++++---------
tools/perf/util/bpf_counter.c | 2 ++
tools/perf/util/config.c | 4 +++
tools/perf/util/evsel.c | 22 +++++++++++++
tools/perf/util/evsel.h | 8 +++++
tools/perf/util/target.h | 5 ---
7 files changed, 66 insertions(+), 20 deletions(-)

diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
index 6ec5960b08c3d..78afe13cd7d47 100644
--- a/tools/perf/Documentation/perf-stat.txt
+++ b/tools/perf/Documentation/perf-stat.txt
@@ -97,6 +97,8 @@ report::
Use BPF programs to aggregate readings from perf_events. This
allows multiple perf-stat sessions that are counting the same metric (cycles,
instructions, etc.) to share hardware counters.
+ To use BPF programs on common hardware events by default, use
+ "perf config stat.bpf-counter-events=<list_of_events>".

--bpf-attr-map::
With option "--bpf-counters", different perf-stat sessions share
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 2a2c15cac80a3..0c76271f3ef53 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -413,6 +413,8 @@ static int read_affinity_counters(struct timespec *rs)
evlist__for_each_entry(evsel_list, counter) {
if (evsel__cpu_iter_skip(counter, cpu))
continue;
+ if (evsel__is_bpf(counter))
+ continue;
if (!counter->err) {
counter->err = read_counter_cpu(counter, rs,
counter->cpu_iter - 1);
@@ -423,17 +425,28 @@ static int read_affinity_counters(struct timespec *rs)
return 0;
}

+/*
+ * Returns:
+ * 0 if all events use BPF;
+ * 1 if some events do NOT use BPF;
+ * < 0 on errors;
+ */
static int read_bpf_map_counters(void)
{
+ bool has_none_bpf_events = false;
struct evsel *counter;
int err;

evlist__for_each_entry(evsel_list, counter) {
+ if (!evsel__is_bpf(counter)) {
+ has_none_bpf_events = true;
+ continue;
+ }
err = bpf_counter__read(counter);
if (err)
return err;
}
- return 0;
+ return has_none_bpf_events ? 1 : 0;
}

static void read_counters(struct timespec *rs)
@@ -442,9 +455,10 @@ static void read_counters(struct timespec *rs)
int err;

if (!stat_config.stop_read_counter) {
- if (target__has_bpf(&target))
- err = read_bpf_map_counters();
- else
+ err = read_bpf_map_counters();
+ if (err < 0)
+ return;
+ if (err)
err = read_affinity_counters(rs);
if (err < 0)
return;
@@ -535,12 +549,13 @@ static int enable_counters(void)
struct evsel *evsel;
int err;

- if (target__has_bpf(&target)) {
- evlist__for_each_entry(evsel_list, evsel) {
- err = bpf_counter__enable(evsel);
- if (err)
- return err;
- }
+ evlist__for_each_entry(evsel_list, evsel) {
+ if (!evsel__is_bpf(evsel))
+ continue;
+
+ err = bpf_counter__enable(evsel);
+ if (err)
+ return err;
}

if (stat_config.initial_delay < 0) {
@@ -784,11 +799,9 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
if (affinity__setup(&affinity) < 0)
return -1;

- if (target__has_bpf(&target)) {
- evlist__for_each_entry(evsel_list, counter) {
- if (bpf_counter__load(counter, &target))
- return -1;
- }
+ evlist__for_each_entry(evsel_list, counter) {
+ if (bpf_counter__load(counter, &target))
+ return -1;
}

evlist__for_each_cpu (evsel_list, i, cpu) {
diff --git a/tools/perf/util/bpf_counter.c b/tools/perf/util/bpf_counter.c
index 5de991ab46af9..3189b63714371 100644
--- a/tools/perf/util/bpf_counter.c
+++ b/tools/perf/util/bpf_counter.c
@@ -792,6 +792,8 @@ int bpf_counter__load(struct evsel *evsel, struct target *target)
evsel->bpf_counter_ops = &bpf_program_profiler_ops;
else if (target->use_bpf)
evsel->bpf_counter_ops = &bperf_ops;
+ else if (evsel__match_bpf_counter_events(evsel->name))
+ evsel->bpf_counter_ops = &bperf_ops;

if (evsel->bpf_counter_ops)
return evsel->bpf_counter_ops->load(evsel, target);
diff --git a/tools/perf/util/config.c b/tools/perf/util/config.c
index 6bcb5ef221f8c..63d472b336de2 100644
--- a/tools/perf/util/config.c
+++ b/tools/perf/util/config.c
@@ -18,6 +18,7 @@
#include "util/hist.h" /* perf_hist_config */
#include "util/llvm-utils.h" /* perf_llvm_config */
#include "util/stat.h" /* perf_stat__set_big_num */
+#include "util/evsel.h" /* evsel__hw_names, evsel__use_bpf_counters */
#include "build-id.h"
#include "debug.h"
#include "config.h"
@@ -460,6 +461,9 @@ static int perf_stat_config(const char *var, const char *value)
if (!strcmp(var, "stat.no-csv-summary"))
perf_stat__set_no_csv_summary(perf_config_bool(var, value));

+ if (!strcmp(var, "stat.bpf-counter-events"))
+ evsel__bpf_counter_events = strdup(value);
+
/* Add other config variables here. */
return 0;
}
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 2d2614eeaa20e..080ddcfefbcd2 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -492,6 +492,28 @@ const char *evsel__hw_names[PERF_COUNT_HW_MAX] = {
"ref-cycles",
};

+char *evsel__bpf_counter_events;
+
+bool evsel__match_bpf_counter_events(const char *name)
+{
+ int name_len;
+ bool match;
+ char *ptr;
+
+ if (!evsel__bpf_counter_events)
+ return false;
+
+ ptr = strstr(evsel__bpf_counter_events, name);
+ name_len = strlen(name);
+
+ /* check name matches a full token in evsel__bpf_counter_events */
+ match = (ptr != NULL) &&
+ ((ptr == evsel__bpf_counter_events) || (*(ptr - 1) == ',')) &&
+ ((*(ptr + name_len) == ',') || (*(ptr + name_len) == '\0'));
+
+ return match;
+}
+
static const char *__evsel__hw_name(u64 config)
{
if (config < PERF_COUNT_HW_MAX && evsel__hw_names[config])
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index eccc4fd5b3eb4..ce4b629d659c2 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -239,6 +239,11 @@ void evsel__calc_id_pos(struct evsel *evsel);

bool evsel__is_cache_op_valid(u8 type, u8 op);

+static inline bool evsel__is_bpf(struct evsel *evsel)
+{
+ return evsel->bpf_counter_ops != NULL;
+}
+
#define EVSEL__MAX_ALIASES 8

extern const char *evsel__hw_cache[PERF_COUNT_HW_CACHE_MAX][EVSEL__MAX_ALIASES];
@@ -246,6 +251,9 @@ extern const char *evsel__hw_cache_op[PERF_COUNT_HW_CACHE_OP_MAX][EVSEL__MAX_ALI
extern const char *evsel__hw_cache_result[PERF_COUNT_HW_CACHE_RESULT_MAX][EVSEL__MAX_ALIASES];
extern const char *evsel__hw_names[PERF_COUNT_HW_MAX];
extern const char *evsel__sw_names[PERF_COUNT_SW_MAX];
+extern char *evsel__bpf_counter_events;
+bool evsel__match_bpf_counter_events(const char *name);
+
int __evsel__hw_cache_type_op_res_name(u8 type, u8 op, u8 result, char *bf, size_t size);
const char *evsel__name(struct evsel *evsel);

diff --git a/tools/perf/util/target.h b/tools/perf/util/target.h
index 1bce3eb28ef25..4ff56217f2a65 100644
--- a/tools/perf/util/target.h
+++ b/tools/perf/util/target.h
@@ -66,11 +66,6 @@ static inline bool target__has_cpu(struct target *target)
return target->system_wide || target->cpu_list;
}

-static inline bool target__has_bpf(struct target *target)
-{
- return target->bpf_str || target->use_bpf;
-}
-
static inline bool target__none(struct target *target)
{
return !target__has_task(target) && !target__has_cpu(target);
--
2.30.2