Re: [PATCH 26/31] perf tools: Support perf event alias name

["Wangnan (F)" <wangnan0@huawei.com>]

On 2015/10/21 16:53, Namhyung Kim wrote:
> Hi,
>
> On Wed, Oct 14, 2015 at 12:41:37PM +0000, Wang Nan wrote:
>> From: He Kuang <hekuang@huawei.com>
>>
>> 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:
>>
>>   # perf record -e mypmu=cycles ...
>>
>> To allow parser refer to existing event selecter, pass event list to
>> 'struct parse_events_evlist'. perf_evlist__find_evsel_by_alias() is
>> introduced to get evsel through its alias.
> What about using event name directly?  I guess the alias name is used
> only to refer an event so it'd be better to use the event name.
> Anyway we need alias as well when event has no name or name is complex.

It is possible to trigger two perf events with same PMU but
different config options:

  # perf record -e cycles/period=9999/ -e cycles/period=99999/ -a sleep 1

In this case the name of events are:

cycles/period=9999/ `
cycles/period=99999/

Using it in perf cmdline is painful:

  # perf record -e cycles/period=9999/ -e cycles/period=99999/ -e 
bpf_program.c/myevent=cycles/period=9999//...

Thank you.

> Thanks
> Namhyung
>
>
>> Signed-off-by: He Kuang <hekuang@huawei.com>
>> Signed-off-by: Wang Nan <wangnan0@huawei.com>
>> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
>> Cc: Alexei Starovoitov <ast@plumgrid.com>
>> Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
>> Cc: Daniel Borkmann <daniel@iogearbox.net>
>> Cc: David Ahern <dsahern@gmail.com>
>> Cc: He Kuang <hekuang@huawei.com>
>> Cc: Jiri Olsa <jolsa@kernel.org>
>> Cc: Kaixu Xia <xiakaixu@huawei.com>
>> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
>> Cc: Namhyung Kim <namhyung@kernel.org>
>> Cc: Paul Mackerras <paulus@samba.org>
>> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
>> Cc: Zefan Li <lizefan@huawei.com>
>> Cc: pi3orama@163.com
>> Link: http://lkml.kernel.org/n/ebpf-7w1s62o0s6ovqlaqwrmx20v9@git.kernel.org
>> ---
>>   tools/perf/util/evlist.c       | 16 ++++++++++++++++
>>   tools/perf/util/evlist.h       |  4 ++++
>>   tools/perf/util/evsel.h        |  1 +
>>   tools/perf/util/parse-events.c | 31 ++++++++++++++++++++++++++++---
>>   tools/perf/util/parse-events.h |  5 +++++
>>   tools/perf/util/parse-events.y | 15 ++++++++++++++-
>>   6 files changed, 68 insertions(+), 4 deletions(-)
>>
>> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
>> index d139219..8dd59aa 100644
>> --- a/tools/perf/util/evlist.c
>> +++ b/tools/perf/util/evlist.c
>> @@ -1753,3 +1753,19 @@ void perf_evlist__set_tracking_event(struct perf_evlist *evlist,
>>   
>>   	tracking_evsel->tracking = true;
>>   }
>> +
>> +struct perf_evsel *
>> +perf_evlist__find_evsel_by_alias(struct perf_evlist *evlist,
>> +				 const char *alias)
>> +{
>> +	struct perf_evsel *evsel;
>> +
>> +	evlist__for_each(evlist, evsel) {
>> +		if (!evsel->alias)
>> +			continue;
>> +		if (strcmp(alias, evsel->alias) == 0)
>> +			return evsel;
>> +	}
>> +
>> +	return NULL;
>> +}
>> diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
>> index a459fe7..4e25342 100644
>> --- a/tools/perf/util/evlist.h
>> +++ b/tools/perf/util/evlist.h
>> @@ -292,4 +292,8 @@ void perf_evlist__set_tracking_event(struct perf_evlist *evlist,
>>   				     struct perf_evsel *tracking_evsel);
>>   
>>   void perf_event_attr__set_max_precise_ip(struct perf_event_attr *attr);
>> +
>> +struct perf_evsel *
>> +perf_evlist__find_evsel_by_alias(struct perf_evlist *evlist, const char *alias);
>> +
>>   #endif /* __PERF_EVLIST_H */
>> diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
>> index a60b5d5..9a95e73 100644
>> --- a/tools/perf/util/evsel.h
>> +++ b/tools/perf/util/evsel.h
>> @@ -87,6 +87,7 @@ 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 4849dbd..06ba5a6 100644
>> --- a/tools/perf/util/parse-events.c
>> +++ b/tools/perf/util/parse-events.c
>> @@ -1020,6 +1020,30 @@ 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;
>> @@ -1373,9 +1397,10 @@ int parse_events(struct perf_evlist *evlist, const char *str,
>>   		 struct parse_events_error *err)
>>   {
>>   	struct parse_events_evlist data = {
>> -		.list  = LIST_HEAD_INIT(data.list),
>> -		.idx   = evlist->nr_entries,
>> -		.error = err,
>> +		.list   = LIST_HEAD_INIT(data.list),
>> +		.idx    = evlist->nr_entries,
>> +		.error  = err,
>> +		.evlist = evlist,
>>   	};
>>   	int ret;
>>   
>> diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
>> index 8f17c83..b525353 100644
>> --- a/tools/perf/util/parse-events.h
>> +++ b/tools/perf/util/parse-events.h
>> @@ -96,6 +96,7 @@ struct parse_events_evlist {
>>   	int			   idx;
>>   	int			   nr_groups;
>>   	struct parse_events_error *error;
>> +	struct perf_evlist	  *evlist;
>>   };
>>   
>>   struct parse_events_terms {
>> @@ -168,4 +169,8 @@ 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 ad37996..90e382f 100644
>> --- a/tools/perf/util/parse-events.y
>> +++ b/tools/perf/util/parse-events.y
>> @@ -76,6 +76,7 @@ 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
>> @@ -192,13 +193,25 @@ 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
>>