Re: [PATCH v2] libperf: Add API for allocating new thread map

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Mon, Feb 21, 2022 at 08:46:49PM +0100, Jiri Olsa escreveu:
> On Mon, Feb 21, 2022 at 12:26:28PM +0200, Tzvetomir Stoyanov (VMware) wrote:
> > The existing API perf_thread_map__new_dummy() allocates new thread map
> > for one thread. I couldn't find a way to reallocate the map with more
> > threads, or to allocate a new map for more than one thread. Having
> > multiple threads in a thread map is essential for some use cases.
> > That's why a new API is proposed, which allocates a new thread map
> > for given number of threads:
> >  perf_thread_map__new_array()
> > 
> > Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
> > ---
> > v2 changes:
> >  - Changed the new API as Arnaldo suggested - get number of threads in the
> >    map and array with initial values (optional).
> 
> looks good, would you also find useful in your use case the comm support

Is that an Acked-by? :-)

- Arnaldo

> in thread_map? the thread_map__read_comms function? we could move it from
> perf to libperf
> 
> thanks,
> jirka
> 
> > 
> >  tools/lib/perf/Documentation/libperf.txt |  1 +
> >  tools/lib/perf/include/perf/threadmap.h  |  1 +
> >  tools/lib/perf/libperf.map               |  1 +
> >  tools/lib/perf/tests/test-threadmap.c    | 41 ++++++++++++++++++++++++
> >  tools/lib/perf/threadmap.c               | 24 ++++++++++----
> >  5 files changed, 61 insertions(+), 7 deletions(-)
> > 
> > diff --git a/tools/lib/perf/Documentation/libperf.txt b/tools/lib/perf/Documentation/libperf.txt
> > index a21f733b95b1..a8f1a237931b 100644
> > --- a/tools/lib/perf/Documentation/libperf.txt
> > +++ b/tools/lib/perf/Documentation/libperf.txt
> > @@ -62,6 +62,7 @@ SYNOPSIS
> >    struct perf_thread_map;
> >  
> >    struct perf_thread_map *perf_thread_map__new_dummy(void);
> > +  struct perf_thread_map *perf_thread_map__new_array(int nr_threads, pid_t *array);
> >  
> >    void perf_thread_map__set_pid(struct perf_thread_map *map, int idx, pid_t pid);
> >    char *perf_thread_map__comm(struct perf_thread_map *map, int idx);
> > diff --git a/tools/lib/perf/include/perf/threadmap.h b/tools/lib/perf/include/perf/threadmap.h
> > index 58f7fbdce446..8b40e7777cea 100644
> > --- a/tools/lib/perf/include/perf/threadmap.h
> > +++ b/tools/lib/perf/include/perf/threadmap.h
> > @@ -8,6 +8,7 @@
> >  struct perf_thread_map;
> >  
> >  LIBPERF_API struct perf_thread_map *perf_thread_map__new_dummy(void);
> > +LIBPERF_API struct perf_thread_map *perf_thread_map__new_array(int nr_threads, pid_t *array);
> >  
> >  LIBPERF_API void perf_thread_map__set_pid(struct perf_thread_map *map, int idx, pid_t pid);
> >  LIBPERF_API char *perf_thread_map__comm(struct perf_thread_map *map, int idx);
> > diff --git a/tools/lib/perf/libperf.map b/tools/lib/perf/libperf.map
> > index 6fa0d651576b..190b56ae923a 100644
> > --- a/tools/lib/perf/libperf.map
> > +++ b/tools/lib/perf/libperf.map
> > @@ -12,6 +12,7 @@ LIBPERF_0.0.1 {
> >  		perf_cpu_map__empty;
> >  		perf_cpu_map__max;
> >  		perf_cpu_map__has;
> > +		perf_thread_map__new_array;
> >  		perf_thread_map__new_dummy;
> >  		perf_thread_map__set_pid;
> >  		perf_thread_map__comm;
> > diff --git a/tools/lib/perf/tests/test-threadmap.c b/tools/lib/perf/tests/test-threadmap.c
> > index 5e2a0291e94c..f728ad7002bb 100644
> > --- a/tools/lib/perf/tests/test-threadmap.c
> > +++ b/tools/lib/perf/tests/test-threadmap.c
> > @@ -11,9 +11,43 @@ static int libperf_print(enum libperf_print_level level,
> >  	return vfprintf(stderr, fmt, ap);
> >  }
> >  
> > +static int test_threadmap_array(int nr, pid_t *array)
> > +{
> > +	struct perf_thread_map *threads;
> > +	int i;
> > +
> > +	threads = perf_thread_map__new_array(nr, array);
> > +	__T("Failed to allocate new thread map", threads);
> > +
> > +	__T("Unexpected number of threads", perf_thread_map__nr(threads) == nr);
> > +
> > +	for (i = 0; i < nr; i++) {
> > +		__T("Unexpected initial value of thread",
> > +		    perf_thread_map__pid(threads, i) == (array ? array[i] : -1));
> > +	}
> > +
> > +	for (i = 1; i < nr; i++)
> > +		perf_thread_map__set_pid(threads, i, i * 100);
> > +
> > +	__T("Unexpected value of thread 0",
> > +	    perf_thread_map__pid(threads, 0) == (array ? array[0] : -1));
> > +
> > +	for (i = 1; i < nr; i++) {
> > +		__T("Unexpected thread value",
> > +		    perf_thread_map__pid(threads, i) == i * 100);
> > +	}
> > +
> > +	perf_thread_map__put(threads);
> > +
> > +	return 0;
> > +}
> > +
> > +#define THREADS_NR	10
> >  int test_threadmap(int argc, char **argv)
> >  {
> >  	struct perf_thread_map *threads;
> > +	pid_t thr_array[THREADS_NR];
> > +	int i;
> >  
> >  	__T_START;
> >  
> > @@ -27,6 +61,13 @@ int test_threadmap(int argc, char **argv)
> >  	perf_thread_map__put(threads);
> >  	perf_thread_map__put(threads);
> >  
> > +	test_threadmap_array(THREADS_NR, NULL);
> > +
> > +	for (i = 0; i < THREADS_NR; i++)
> > +		thr_array[i] = i + 100;
> > +
> > +	test_threadmap_array(THREADS_NR, thr_array);
> > +
> >  	__T_END;
> >  	return tests_failed == 0 ? 0 : -1;
> >  }
> > diff --git a/tools/lib/perf/threadmap.c b/tools/lib/perf/threadmap.c
> > index 84fa07c79d00..07968f3ea093 100644
> > --- a/tools/lib/perf/threadmap.c
> > +++ b/tools/lib/perf/threadmap.c
> > @@ -42,18 +42,28 @@ char *perf_thread_map__comm(struct perf_thread_map *map, int idx)
> >  	return map->map[idx].comm;
> >  }
> >  
> > -struct perf_thread_map *perf_thread_map__new_dummy(void)
> > +struct perf_thread_map *perf_thread_map__new_array(int nr_threads, pid_t *array)
> >  {
> > -	struct perf_thread_map *threads = thread_map__alloc(1);
> > +	struct perf_thread_map *threads = thread_map__alloc(nr_threads);
> > +	int i;
> > +
> > +	if (!threads)
> > +		return NULL;
> > +
> > +	for (i = 0; i < nr_threads; i++)
> > +		perf_thread_map__set_pid(threads, i, array ? array[i] : -1);
> > +
> > +	threads->nr = nr_threads;
> > +	refcount_set(&threads->refcnt, 1);
> >  
> > -	if (threads != NULL) {
> > -		perf_thread_map__set_pid(threads, 0, -1);
> > -		threads->nr = 1;
> > -		refcount_set(&threads->refcnt, 1);
> > -	}
> >  	return threads;
> >  }
> >  
> > +struct perf_thread_map *perf_thread_map__new_dummy(void)
> > +{
> > +	return perf_thread_map__new_array(1, NULL);
> > +}
> > +
> >  static void perf_thread_map__delete(struct perf_thread_map *threads)
> >  {
> >  	if (threads) {
> > -- 
> > 2.34.1
> > 

-- 

- Arnaldo