Commit 3a69672e authored by Namhyung Kim's avatar Namhyung Kim Committed by Arnaldo Carvalho de Melo
Browse files

perf pmu: Add perf_pmu__{open,scan}_file_at() 



These two helpers will also use openat() to reduce the overhead with
relative pathnames.  Convert other functions in pmu_lookup() to use
the new helpers.

Committer testing:

Before:

  ⬢[acme@toolbox perf-tools-next]$ perf bench internals pmu-scan
  # Running 'internals/pmu-scan' benchmark:
  Computing performance of sysfs PMU event scan for 100 times
    Average PMU scanning took: 2729.040 usec (+- 7.117 usec)
  ⬢[acme@toolbox perf-tools-next]$

After:

  ⬢[acme@toolbox perf-tools-next]$ perf bench internals pmu-scan
  # Running 'internals/pmu-scan' benchmark:
  Computing performance of sysfs PMU event scan for 100 times
    Average PMU scanning took: 2419.870 usec (+- 9.057 usec)
  ⬢[acme@toolbox perf-tools-next]$

Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Acked-by: default avatarIan Rogers <irogers@google.com>
Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230331202949.810326-2-namhyung@kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 46378665

tools/perf/util/pmu.c

+45 −12
Original line number Diff line number Diff line
@@ -567,7 +567,7 @@ static void pmu_read_sysfs(void) 
 * Uncore PMUs have a "cpumask" file under sysfs. CPU PMUs (e.g. on arm/arm64)

 * may have a "cpus" file.

 */

static struct perf_cpu_map *pmu_cpumask(const char *name)

static struct perf_cpu_map *pmu_cpumask(int dirfd, const char *name)

{

	struct perf_cpu_map *cpus;

	const char *templates[] = {
@@ -582,10 +582,11 @@ static struct perf_cpu_map *pmu_cpumask(const char *name) 


	strlcpy(pmu_name, name, sizeof(pmu_name));

	for (template = templates; *template; template++) {

		file = perf_pmu__open_file(&pmu, *template);

		file = perf_pmu__open_file_at(&pmu, dirfd, *template);

		if (!file)

			continue;

		cpus = perf_cpu_map__read(file);

		fclose(file);

		if (cpus)

			return cpus;

	}
@@ -593,15 +594,19 @@ static struct perf_cpu_map *pmu_cpumask(const char *name) 
	return NULL;

}



static bool pmu_is_uncore(const char *name)

static bool pmu_is_uncore(int dirfd, const char *name)

{

	char path[PATH_MAX];

	int fd;



	if (perf_pmu__hybrid_mounted(name))

		return false;



	perf_pmu__pathname_scnprintf(path, sizeof(path), name, "cpumask");

	return file_available(path);

	fd = perf_pmu__pathname_fd(dirfd, name, "cpumask", O_PATH);

	if (fd < 0)

		return false;



	close(fd);

	return true;

}



static char *pmu_id(const char *name)
@@ -853,11 +858,11 @@ pmu_find_alias_name(const char *name __maybe_unused) 
	return NULL;

}



static int pmu_max_precise(struct perf_pmu *pmu)

static int pmu_max_precise(int dirfd, struct perf_pmu *pmu)

{

	int max_precise = -1;



	perf_pmu__scan_file(pmu, "caps/max_precise", "%d", &max_precise);

	perf_pmu__scan_file_at(pmu, dirfd, "caps/max_precise", "%d", &max_precise);

	return max_precise;

}
@@ -895,14 +900,14 @@ static struct perf_pmu *pmu_lookup(int dirfd, const char *lookup_name) 
	if (!pmu)

		return NULL;



	pmu->cpus = pmu_cpumask(name);

	pmu->cpus = pmu_cpumask(dirfd, name);

	pmu->name = strdup(name);



	if (!pmu->name)

		goto err;



	/* Read type, and ensure that type value is successfully assigned (return 1) */

	if (perf_pmu__scan_file(pmu, "type", "%u", &type) != 1)

	if (perf_pmu__scan_file_at(pmu, dirfd, "type", "%u", &type) != 1)

		goto err;



	alias_name = pmu_find_alias_name(name);
@@ -913,10 +918,10 @@ static struct perf_pmu *pmu_lookup(int dirfd, const char *lookup_name) 
	}



	pmu->type = type;

	pmu->is_uncore = pmu_is_uncore(name);

	pmu->is_uncore = pmu_is_uncore(dirfd, name);

	if (pmu->is_uncore)

		pmu->id = pmu_id(name);

	pmu->max_precise = pmu_max_precise(pmu);

	pmu->max_precise = pmu_max_precise(dirfd, pmu);

	pmu_add_cpu_aliases(&aliases, pmu);

	pmu_add_sys_aliases(&aliases, pmu);
@@ -1730,6 +1735,17 @@ FILE *perf_pmu__open_file(struct perf_pmu *pmu, const char *name) 
	return fopen(path, "r");

}



FILE *perf_pmu__open_file_at(struct perf_pmu *pmu, int dirfd, const char *name)

{

	int fd;



	fd = perf_pmu__pathname_fd(dirfd, pmu->name, name, O_RDONLY);

	if (fd < 0)

		return NULL;



	return fdopen(fd, "r");

}



int perf_pmu__scan_file(struct perf_pmu *pmu, const char *name, const char *fmt,

			...)

{
@@ -1747,6 +1763,23 @@ int perf_pmu__scan_file(struct perf_pmu *pmu, const char *name, const char *fmt, 
	return ret;

}



int perf_pmu__scan_file_at(struct perf_pmu *pmu, int dirfd, const char *name,

			   const char *fmt, ...)

{

	va_list args;

	FILE *file;

	int ret = EOF;



	va_start(args, fmt);

	file = perf_pmu__open_file_at(pmu, dirfd, name);

	if (file) {

		ret = vfscanf(file, fmt, args);

		fclose(file);

	}

	va_end(args);

	return ret;

}



bool perf_pmu__file_exists(struct perf_pmu *pmu, const char *name)

{

	char path[PATH_MAX];

tools/perf/util/pmu.h

+5 −1
Original line number Diff line number Diff line
@@ -220,7 +220,12 @@ bool is_pmu_core(const char *name); 
void print_pmu_events(const struct print_callbacks *print_cb, void *print_state);

bool pmu_have_event(const char *pname, const char *name);



FILE *perf_pmu__open_file(struct perf_pmu *pmu, const char *name);

FILE *perf_pmu__open_file_at(struct perf_pmu *pmu, int dirfd, const char *name);



int perf_pmu__scan_file(struct perf_pmu *pmu, const char *name, const char *fmt, ...) __scanf(3, 4);

int perf_pmu__scan_file_at(struct perf_pmu *pmu, int dirfd, const char *name,

			   const char *fmt, ...) __scanf(4, 5);



bool perf_pmu__file_exists(struct perf_pmu *pmu, const char *name);
@@ -259,7 +264,6 @@ int perf_pmu__pathname_scnprintf(char *buf, size_t size, 
				 const char *pmu_name, const char *filename);

int perf_pmu__event_source_devices_fd(void);

int perf_pmu__pathname_fd(int dirfd, const char *pmu_name, const char *filename, int flags);

FILE *perf_pmu__open_file(struct perf_pmu *pmu, const char *name);



void perf_pmu__destroy(void);