[PATCH v3 0/4] perf util: bpf perf improvements

[PATCH v3 0/4] perf util: bpf perf improvements

[Song Liu]

This patches set improves bpf_perf (perf-stat --bpf-counter) by
  1) exposing key definitions to a libperf header;
  2) adding compatibility check for perf_attr_map;
  3) introducing config stat.bpf-counter-events.
  4) introducing 'b' modify to event parser.

Changes v2 => v3:
1. Add 'b' modifier. (Jiri)
2. Allow configuring stat.bpf-counter-events with any event name (instead
   of limiting to hardware events). (Jiri)

Changes v1 => v2:
1. Separte 2/3 from 1/3. (Jiri)
2. Rename bperf.h to bpf_perf.h. (Jiri)
3. Other small fixes/optimizations. (Jiri)

Song Liu (4):
  perf util: move bpf_perf definitions to a libperf header
  perf bpf: check perf_attr_map is compatible with the perf binary
  perf-stat: introduce config stat.bpf-counter-events
  perf-stat: introduce ':b' modifier

 tools/lib/perf/include/perf/bpf_perf.h | 31 ++++++++++++++++
 tools/perf/Documentation/perf-stat.txt |  2 ++
 tools/perf/builtin-stat.c              | 43 ++++++++++++++--------
 tools/perf/util/bpf_counter.c          | 50 +++++++++++++-------------
 tools/perf/util/config.c               |  4 +++
 tools/perf/util/evsel.c                | 22 ++++++++++++
 tools/perf/util/evsel.h                |  9 +++++
 tools/perf/util/parse-events.c         |  8 ++++-
 tools/perf/util/parse-events.l         |  2 +-
 tools/perf/util/target.h               |  5 ---
 10 files changed, 129 insertions(+), 47 deletions(-)
 create mode 100644 tools/lib/perf/include/perf/bpf_perf.h

--
2.30.2

[PATCH v3 1/4] perf util: move bpf_perf definitions to a libperf header

[Song Liu]

By following the same protocol, other tools can share hardware PMCs with
perf. Move perf_event_attr_map_entry and BPF_PERF_DEFAULT_ATTR_MAP_PATH to
bpf_perf.h for other tools to use.

Signed-off-by: Song Liu <song@kernel.org>
---
 tools/lib/perf/include/perf/bpf_perf.h | 31 ++++++++++++++++++++++++++
 tools/perf/util/bpf_counter.c          | 27 +++-------------------
 2 files changed, 34 insertions(+), 24 deletions(-)
 create mode 100644 tools/lib/perf/include/perf/bpf_perf.h

diff --git a/tools/lib/perf/include/perf/bpf_perf.h b/tools/lib/perf/include/perf/bpf_perf.h
new file mode 100644
index 0000000000000..e7cf6ba7b674b
--- /dev/null
+++ b/tools/lib/perf/include/perf/bpf_perf.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+#ifndef __LIBPERF_BPF_PERF_H
+#define __LIBPERF_BPF_PERF_H
+
+#include <linux/types.h>  /* for __u32 */
+
+/*
+ * bpf_perf uses a hashmap, the attr_map, to track all the leader programs.
+ * The hashmap is pinned in bpffs. flock() on this file is used to ensure
+ * no concurrent access to the attr_map.  The key of attr_map is struct
+ * perf_event_attr, and the value is struct perf_event_attr_map_entry.
+ *
+ * struct perf_event_attr_map_entry contains two __u32 IDs, bpf_link of the
+ * leader prog, and the diff_map. Each perf-stat session holds a reference
+ * to the bpf_link to make sure the leader prog is attached to sched_switch
+ * tracepoint.
+ *
+ * Since the hashmap only contains IDs of the bpf_link and diff_map, it
+ * does not hold any references to the leader program. Once all perf-stat
+ * sessions of these events exit, the leader prog, its maps, and the
+ * perf_events will be freed.
+ */
+struct perf_event_attr_map_entry {
+	__u32 link_id;
+	__u32 diff_map_id;
+};
+
+/* default attr_map name */
+#define BPF_PERF_DEFAULT_ATTR_MAP_PATH "perf_attr_map"
+
+#endif /* __LIBPERF_BPF_PERF_H */
diff --git a/tools/perf/util/bpf_counter.c b/tools/perf/util/bpf_counter.c
index 81d1df3c4ec0e..be484ddbbd5be 100644
--- a/tools/perf/util/bpf_counter.c
+++ b/tools/perf/util/bpf_counter.c
@@ -14,6 +14,7 @@
 #include <bpf/btf.h>
 #include <bpf/libbpf.h>
 #include <api/fs/fs.h>
+#include <perf/bpf_perf.h>
 
 #include "bpf_counter.h"
 #include "counts.h"
@@ -29,28 +30,6 @@
 #include "bpf_skel/bperf_leader.skel.h"
 #include "bpf_skel/bperf_follower.skel.h"
 
-/*
- * bperf uses a hashmap, the attr_map, to track all the leader programs.
- * The hashmap is pinned in bpffs. flock() on this file is used to ensure
- * no concurrent access to the attr_map.  The key of attr_map is struct
- * perf_event_attr, and the value is struct perf_event_attr_map_entry.
- *
- * struct perf_event_attr_map_entry contains two __u32 IDs, bpf_link of the
- * leader prog, and the diff_map. Each perf-stat session holds a reference
- * to the bpf_link to make sure the leader prog is attached to sched_switch
- * tracepoint.
- *
- * Since the hashmap only contains IDs of the bpf_link and diff_map, it
- * does not hold any references to the leader program. Once all perf-stat
- * sessions of these events exit, the leader prog, its maps, and the
- * perf_events will be freed.
- */
-struct perf_event_attr_map_entry {
-	__u32 link_id;
-	__u32 diff_map_id;
-};
-
-#define DEFAULT_ATTR_MAP_PATH "fs/bpf/perf_attr_map"
 #define ATTR_MAP_SIZE 16
 
 static inline void *u64_to_ptr(__u64 ptr)
@@ -341,8 +320,8 @@ static int bperf_lock_attr_map(struct target *target)
 	if (target->attr_map) {
 		scnprintf(path, PATH_MAX, "%s", target->attr_map);
 	} else {
-		scnprintf(path, PATH_MAX, "%s/%s", sysfs__mountpoint(),
-			  DEFAULT_ATTR_MAP_PATH);
+		scnprintf(path, PATH_MAX, "%s/fs/bpf/%s", sysfs__mountpoint(),
+			  BPF_PERF_DEFAULT_ATTR_MAP_PATH);
 	}
 
 	if (access(path, F_OK)) {
-- 
2.30.2

[PATCH v3 2/4] perf bpf: check perf_attr_map is compatible with the perf binary

[Song Liu]

perf_attr_map could be shared among different version of perf binary. Add
bperf_attr_map_compatible() to check whether the existing attr_map is
compatible with current perf binary.

Signed-off-by: Song Liu <song@kernel.org>
---
 tools/perf/util/bpf_counter.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/tools/perf/util/bpf_counter.c b/tools/perf/util/bpf_counter.c
index be484ddbbd5be..5de991ab46af9 100644
--- a/tools/perf/util/bpf_counter.c
+++ b/tools/perf/util/bpf_counter.c
@@ -312,6 +312,20 @@ static __u32 bpf_map_get_id(int fd)
 	return map_info.id;
 }
 
+static bool bperf_attr_map_compatible(int attr_map_fd)
+{
+	struct bpf_map_info map_info = {0};
+	__u32 map_info_len = sizeof(map_info);
+	int err;
+
+	err = bpf_obj_get_info_by_fd(attr_map_fd, &map_info, &map_info_len);
+
+	if (err)
+		return false;
+	return (map_info.key_size == sizeof(struct perf_event_attr)) &&
+		(map_info.value_size == sizeof(struct perf_event_attr_map_entry));
+}
+
 static int bperf_lock_attr_map(struct target *target)
 {
 	char path[PATH_MAX];
@@ -346,6 +360,11 @@ static int bperf_lock_attr_map(struct target *target)
 			return -1;
 	}
 
+	if (!bperf_attr_map_compatible(map_fd)) {
+		close(map_fd);
+		return -1;
+
+	}
 	err = flock(map_fd, LOCK_EX);
 	if (err) {
 		close(map_fd);
-- 
2.30.2

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

[Song Liu]

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

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

[Namhyung Kim]

Hi Song,

On Sat, Apr 17, 2021 at 7:13 AM Song Liu <song@kernel.org> wrote:
>
> 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>
> ---
> @@ -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;

I just realized it doesn't have a disable counterpart.

>         }
>
>         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) {

[SNIP]
> 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'));

I'm not sure we have an event name which is a substring of another.
Maybe it can retry if it fails to match.

Thanks,
Namhyung

> +
> +       return match;
> +}
> +
>  static const char *__evsel__hw_name(u64 config)
>  {
>         if (config < PERF_COUNT_HW_MAX && evsel__hw_names[config])

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

[Song Liu]

> On Apr 17, 2021, at 9:45 AM, Namhyung Kim <namhyung@kernel.org> wrote:
> 
> Hi Song,
> 
> On Sat, Apr 17, 2021 at 7:13 AM Song Liu <song@kernel.org> wrote:
>> 
>> 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>
>> ---
>> @@ -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;
> 
> I just realized it doesn't have a disable counterpart.

I guess it is not really necessary for perf-stat? It is probably good
to have it though. How about we do it in a follow up patch?

[...]

>> +       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'));
> 
> I'm not sure we have an event name which is a substring of another.
> Maybe it can retry if it fails to match.

We have ref-cycles and cycles. And some raw events may be substring of others?

Thanks,
Song

[...]

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

[Jiri Olsa]

On Mon, Apr 19, 2021 at 08:26:02PM +0000, Song Liu wrote:
> 
> 
> > On Apr 17, 2021, at 9:45 AM, Namhyung Kim <namhyung@kernel.org> wrote:
> > 
> > Hi Song,
> > 
> > On Sat, Apr 17, 2021 at 7:13 AM Song Liu <song@kernel.org> wrote:
> >> 
> >> 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>
> >> ---
> >> @@ -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;
> > 
> > I just realized it doesn't have a disable counterpart.
> 
> I guess it is not really necessary for perf-stat? It is probably good
> to have it though. How about we do it in a follow up patch?

good catch, should it at least do:
  evsel->follower_skel->bss->enabled = 0;

because then the follower goes down only with perf process, right?
still doing the counts till the end..?

also while checking on that I realized we open the counters
in separate path for this in bperf_reload_leader_program by
calling evsel__open_per_cpu.. and we're missing all the
fallback code and setup from create_perf_stat_counter

I think we should at least call create_perf_stat_counter,
and also propagate error value if it fails

jirka

> 
> [...]
> 
> >> +       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'));
> > 
> > I'm not sure we have an event name which is a substring of another.
> > Maybe it can retry if it fails to match.
> 
> We have ref-cycles and cycles. And some raw events may be substring of others?
> 
> Thanks,
> Song
> 
> [...]
> 

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

[Jiri Olsa]

On Fri, Apr 16, 2021 at 03:13:24PM -0700, Song Liu wrote:

SNIP

> +/*
> + * 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);

this part is confusing for me.. I understand we don't want to enter
read_affinity_counters when there's no bpf counter, so we don't set
affinities in vain.. but there must be better way ;-)

> 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;

please put this with the target->use_bpf check,
it seems like it's another thing

thanks,
jirka

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

[Song Liu]

> On Apr 19, 2021, at 7:26 AM, Jiri Olsa <jolsa@redhat.com> wrote:
> 
> On Fri, Apr 16, 2021 at 03:13:24PM -0700, Song Liu wrote:
> 
> SNIP
> 
>> +/*
>> + * 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);
> 
> this part is confusing for me.. I understand we don't want to enter
> read_affinity_counters when there's no bpf counter, so we don't set
> affinities in vain.. but there must be better way ;-)
> 
>> 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;
> 
> please put this with the target->use_bpf check,
> it seems like it's another thing

Thanks for the review. Fixing these in v4. 

Song

[PATCH v3 4/4] perf-stat: introduce ':b' modifier

[Song Liu]

Introduce 'b' modifier to event parser, which means use BPF program to
manage this event. This is the same as --bpf-counters option, but only
applies to this event. For example,

  perf stat -e cycles:b,cs               # use bpf for cycles, but not cs
  perf stat -e cycles,cs --bpf-counters  # use bpf for both cycles and cs

Suggested-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Song Liu <song@kernel.org>
---
 tools/perf/util/bpf_counter.c  | 2 +-
 tools/perf/util/evsel.h        | 1 +
 tools/perf/util/parse-events.c | 8 +++++++-
 tools/perf/util/parse-events.l | 2 +-
 4 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/bpf_counter.c b/tools/perf/util/bpf_counter.c
index 3189b63714371..7b4d511c7e6ec 100644
--- a/tools/perf/util/bpf_counter.c
+++ b/tools/perf/util/bpf_counter.c
@@ -790,7 +790,7 @@ int bpf_counter__load(struct evsel *evsel, struct target *target)
 {
 	if (target->bpf_str)
 		evsel->bpf_counter_ops = &bpf_program_profiler_ops;
-	else if (target->use_bpf)
+	else if (target->use_bpf || evsel->bpf_counter)
 		evsel->bpf_counter_ops = &bperf_ops;
 	else if (evsel__match_bpf_counter_events(evsel->name))
 		evsel->bpf_counter_ops = &bperf_ops;
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index ce4b629d659c2..8f66cdcb338d0 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -82,6 +82,7 @@ struct evsel {
 		bool			auto_merge_stats;
 		bool			collect_stat;
 		bool			weak_group;
+		bool			bpf_counter;
 		int			bpf_fd;
 		struct bpf_object	*bpf_obj;
 	};
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 8123d218ad17c..46ebd269a98d1 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1804,6 +1804,7 @@ struct event_modifier {
 	int pinned;
 	int weak;
 	int exclusive;
+	int bpf_counter;
 };
 
 static int get_event_modifier(struct event_modifier *mod, char *str,
@@ -1824,6 +1825,7 @@ static int get_event_modifier(struct event_modifier *mod, char *str,
 	int exclude = eu | ek | eh;
 	int exclude_GH = evsel ? evsel->exclude_GH : 0;
 	int weak = 0;
+	int bpf_counter = 0;
 
 	memset(mod, 0, sizeof(*mod));
 
@@ -1867,6 +1869,8 @@ static int get_event_modifier(struct event_modifier *mod, char *str,
 			exclusive = 1;
 		} else if (*str == 'W') {
 			weak = 1;
+		} else if (*str == 'b') {
+			bpf_counter = 1;
 		} else
 			break;
 
@@ -1898,6 +1902,7 @@ static int get_event_modifier(struct event_modifier *mod, char *str,
 	mod->sample_read = sample_read;
 	mod->pinned = pinned;
 	mod->weak = weak;
+	mod->bpf_counter = bpf_counter;
 	mod->exclusive = exclusive;
 
 	return 0;
@@ -1912,7 +1917,7 @@ static int check_modifier(char *str)
 	char *p = str;
 
 	/* The sizeof includes 0 byte as well. */
-	if (strlen(str) > (sizeof("ukhGHpppPSDIWe") - 1))
+	if (strlen(str) > (sizeof("ukhGHpppPSDIWeb") - 1))
 		return -1;
 
 	while (*p) {
@@ -1953,6 +1958,7 @@ int parse_events__modifier_event(struct list_head *list, char *str, bool add)
 		evsel->sample_read         = mod.sample_read;
 		evsel->precise_max         = mod.precise_max;
 		evsel->weak_group	   = mod.weak;
+		evsel->bpf_counter	   = mod.bpf_counter;
 
 		if (evsel__is_group_leader(evsel)) {
 			evsel->core.attr.pinned = mod.pinned;
diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
index 0b36285a9435d..fb8646cc3e834 100644
--- a/tools/perf/util/parse-events.l
+++ b/tools/perf/util/parse-events.l
@@ -210,7 +210,7 @@ name_tag	[\'][a-zA-Z_*?\[\]][a-zA-Z0-9_*?\-,\.\[\]:=]*[\']
 name_minus	[a-zA-Z_*?][a-zA-Z0-9\-_*?.:]*
 drv_cfg_term	[a-zA-Z0-9_\.]+(=[a-zA-Z0-9_*?\.:]+)?
 /* If you add a modifier you need to update check_modifier() */
-modifier_event	[ukhpPGHSDIWe]+
+modifier_event	[ukhpPGHSDIWeb]+
 modifier_bp	[rwx]{1,3}
 
 %%
-- 
2.30.2