[PATCH 22/53] perf tools: Support perf event alias name

From: Wang Nan
Date: Mon Jan 11 2016 - 09:15:46 EST

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From: He Kuang <hekuang@xxxxxxxxxx>

This patch is useful when trying to pass a perf event to BPF map.
Before this patch we are unable to pass an event with config term to
BPF maps. For example:

# perf record -a -e cycles/no-inherit,period=0x7fffffffffffffff/ \
-e './test_bpf_map_2.c/maps:pmu_map.event=cycles/no-inherit,period=0x7fffffffffffffff//' ls /
event syntax error: '..ps:pmu_map.event=cycles/'
\___ Event not found for map setting

Because those '/' and ',' embarrass parser.

This patch adds new bison rules for specifying an alias name to a perf
event, which allows cmdline refer to previous defined perf event through
its name. With this patch user can give alias name to a perf event using
following cmdline. The above goal can be achieved using:

# perf record -a -e cyc=cycles/no-inherit,period=0x7fffffffffffffff/ \
-e './test_bpf_map_2.c/maps:pmu_map.event=cyc/' ls /

If alias is not provided (normal case):

# perf record -e cycles ...

It will be set to event's name automatically ('cycles' in the above
example).

To allow parser refer to existing event selector, pass event list to
'struct parse_events_evlist'. perf_evlist__find_evsel_by_alias() is
introduced to get evsel through its alias.

Test result:
# cat ./test_bpf_map_2.c
/************************ BEGIN **************************/
#include <uapi/linux/bpf.h>
#define SEC(NAME) __attribute__((section(NAME), used))
struct bpf_map_def {
unsigned int type;
unsigned int key_size;
unsigned int value_size;
unsigned int max_entries;
};
static int (*trace_printk)(const char *fmt, int fmt_size, ...) =
(void *)BPF_FUNC_trace_printk;
static int (*get_smp_processor_id)(void) =
(void *)BPF_FUNC_get_smp_processor_id;
static int (*perf_event_read)(struct bpf_map_def *, int) =
(void *)BPF_FUNC_perf_event_read;

struct bpf_map_def SEC("maps") pmu_map = {
.type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
.key_size = sizeof(int),
.value_size = sizeof(int),
.max_entries = __NR_CPUS__,
};
SEC("func_write=sys_write")
int func_write(void *ctx)
{
unsigned long long val;
char fmt[] = "sys_write: pmu=%llu\n";
val = perf_event_read(&pmu_map, get_smp_processor_id());
trace_printk(fmt, sizeof(fmt), val);
return 0;
}

SEC("func_write_return=sys_write%return")
int func_write_return(void *ctx)
{
unsigned long long val = 0;
char fmt[] = "sys_write_return: pmu=%llu\n";
val = perf_event_read(&pmu_map, get_smp_processor_id());
trace_printk(fmt, sizeof(fmt), val);
return 0;
}
char _license[] SEC("license") = "GPL";
int _version SEC("version") = LINUX_VERSION_CODE;
/************************* END ***************************/
# echo "" > /sys/kernel/debug/tracing/trace
# ./perf record -a -e cyc=cycles/no-inherit,period=0x7fffffffffffffff/ \
-e './test_bpf_map_2.c/maps:pmu_map.event=cyc/' ls /
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.755 MB perf.data ]
# cat /sys/kernel/debug/tracing/trace | grep ls
ls-25328 [002] d... 940138.313178: : sys_write: pmu=4503165
ls-25328 [002] dN.. 940138.313207: : sys_write_return: pmu=4582975
ls-25328 [002] d... 940138.313211: : sys_write: pmu=4599840
ls-25328 [002] dN.. 940138.313220: : sys_write_return: pmu=4633352
# ./perf report --stdio
Error:
The perf.data file has no samples!
...
(This is expected because we set period of cycles to a very large
value to period of cycles event because we want to use this event
as a counter only, don't need sampling)

# ./perf record -e cycles -e './test_bpf_map_2.c/maps:pmu_map.event=cycles/' ls /
ERROR: Apply config to BPF failed: Doesn't support inherit event (Hint: use -i or use /no-inherit/ to turn off inherit)

Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
---
tools/perf/util/bpf-loader.c | 2 +-
tools/perf/util/evlist.c | 4 ++--
tools/perf/util/evsel.c | 1 +
tools/perf/util/evsel.h | 1 +
tools/perf/util/parse-events.c | 26 ++++++++++++++++++++++++++
tools/perf/util/parse-events.h | 4 ++++
tools/perf/util/parse-events.y | 15 ++++++++++++++-
7 files changed, 49 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index 84b4581..2893b4e 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -1448,7 +1448,7 @@ int bpf__strerror_apply_obj_config(int err, char *buf, size_t size)
bpf__strerror_entry(BPF_LOADER_ERRNO__OBJCONF_MAP_EVTDIM,
"Cannot set event to BPF maps in multi-thread tracing");
bpf__strerror_entry(BPF_LOADER_ERRNO__OBJCONF_MAP_EVTINH,
- "%s (Hint: use -i to turn off inherit)", emsg);
+ "%s (Hint: use -i or use /no-inherit/ to turn off inherit)", emsg);
bpf__strerror_entry(BPF_LOADER_ERRNO__OBJCONF_MAP_EVTTYPE,
"Can only put raw, hardware and BPF output event into a BPF map");
bpf__strerror_end(buf, size);
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 9b56390..890b08b 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -1731,9 +1731,9 @@ perf_evlist__find_evsel_by_str(struct perf_evlist *evlist,
struct perf_evsel *evsel;

evlist__for_each(evlist, evsel) {
- if (!evsel->name)
+ if (!evsel->alias)
continue;
- if (strcmp(str, evsel->name) == 0)
+ if (strcmp(str, evsel->alias) == 0)
return evsel;
}

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index cdbaf9b..a6b3b07 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1076,6 +1076,7 @@ void perf_evsel__exit(struct perf_evsel *evsel)
thread_map__put(evsel->threads);
zfree(&evsel->group_name);
zfree(&evsel->name);
+ zfree(&evsel->alias);
perf_evsel__object.fini(evsel);
}

diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 8e75434..19885fb 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -89,6 +89,7 @@ struct perf_evsel {
int idx;
u32 ids;
char *name;
+ char *alias;
double scale;
const char *unit;
struct event_format *tp_format;
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 6e2543c..1e0ac77 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1091,6 +1091,30 @@ int parse_events__modifier_group(struct list_head *list,
return parse_events__modifier_event(list, event_mod, true);
}

+int parse_events__set_event_alias(struct parse_events_evlist *data,
+ struct list_head *list,
+ const char *str,
+ void *loc_alias_)
+{
+ struct perf_evsel *evsel;
+ YYLTYPE *loc_alias = loc_alias_;
+
+ if (!str)
+ return 0;
+
+ if (!list_is_singular(list)) {
+ struct parse_events_error *err = data->error;
+
+ err->idx = loc_alias->first_column;
+ err->str = strdup("One alias can be applied to one event only");
+ return -EINVAL;
+ }
+
+ evsel = list_first_entry(list, struct perf_evsel, node);
+ evsel->alias = strdup(str);
+ return evsel->alias ? 0 : -ENOMEM;
+}
+
void parse_events__set_leader(char *name, struct list_head *list)
{
struct perf_evsel *leader;
@@ -1283,6 +1307,8 @@ int parse_events_name(struct list_head *list, char *name)
__evlist__for_each(list, evsel) {
if (!evsel->name)
evsel->name = strdup(name);
+ if (!evsel->alias)
+ evsel->alias = strdup(name);
}

return 0;
diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
index 2a2b172..20ad3c2 100644
--- a/tools/perf/util/parse-events.h
+++ b/tools/perf/util/parse-events.h
@@ -172,4 +172,8 @@ extern int is_valid_tracepoint(const char *event_string);
int valid_event_mount(const char *eventfs);
char *parse_events_formats_error_string(char *additional_terms);

+int parse_events__set_event_alias(struct parse_events_evlist *data,
+ struct list_head *list,
+ const char *str,
+ void *loc_alias_);
#endif /* __PERF_PARSE_EVENTS_H */
diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
index 8992d16..c3cbd7a 100644
--- a/tools/perf/util/parse-events.y
+++ b/tools/perf/util/parse-events.y
@@ -77,6 +77,7 @@ static inc_group_count(struct list_head *list,
%type <head> event_bpf_file
%type <head> event_def
%type <head> event_mod
+%type <head> event_alias
%type <head> event_name
%type <head> event
%type <head> events
@@ -193,13 +194,25 @@ event_name PE_MODIFIER_EVENT
event_name

event_name:
-PE_EVENT_NAME event_def
+PE_EVENT_NAME event_alias
{
ABORT_ON(parse_events_name($2, $1));
free($1);
$$ = $2;
}
|
+event_alias
+
+event_alias:
+PE_NAME '=' event_def
+{
+ struct list_head *list = $3;
+ struct parse_events_evlist *data = _data;
+
+ ABORT_ON(parse_events__set_event_alias(data, list, $1, &@1));
+ $$ = list;
+}
+|
event_def

event_def: event_pmu |
--
1.8.3.4

Next message: Wang Nan: "[PATCH 03/53] perf tools: Set parallel making options build-test"
Previous message: Wang Nan: "[PATCH 25/53] perf tools: Introduce bpf-output event"
In reply to: Wang Nan: "[PATCH 25/53] perf tools: Introduce bpf-output event"
Next in thread: Wang Nan: "[PATCH 03/53] perf tools: Set parallel making options build-test"
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