Commit 8d4b6d37 authored by Ian Rogers's avatar Ian Rogers Committed by Arnaldo Carvalho de Melo
Browse files

perf pmu: Lazily load sysfs aliases 



Don't load sysfs aliases for a PMU when the PMU is first created, defer
until an alias needs to be found. For the pmu-scan benchmark, average
core PMU scanning is reduced by 30.8%, and average PMU scanning by
12.6%.

Signed-off-by: default avatarIan Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Gaosheng Cui <cuigaosheng1@huawei.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jing Zhang <renyu.zj@linux.alibaba.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230824041330.266337-17-irogers@google.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 7b723dbb

tools/perf/tests/pmu-events.c

+2 −0
Original line number Diff line number Diff line
@@ -547,6 +547,7 @@ static int __test_core_pmu_event_aliases(char *pmu_name, int *count) 
	pmu->events_table = table;

	pmu_add_cpu_aliases_table(pmu, table);

	pmu->cpu_aliases_added = true;

	pmu->sysfs_aliases_loaded = true;



	res = pmu_events_table__find_event(table, pmu, "bp_l1_btb_correct", NULL, NULL);

	if (res != 0) {
@@ -588,6 +589,7 @@ static int __test_uncore_pmu_event_aliases(struct perf_pmu_test_pmu *test_pmu) 
	pmu->events_table = events_table;

	pmu_add_cpu_aliases_table(pmu, events_table);

	pmu->cpu_aliases_added = true;

	pmu->sysfs_aliases_loaded = true;

	pmu_add_sys_aliases(pmu);



	/* Count how many aliases we generated */

tools/perf/util/pmu.c

+42 −39
Original line number Diff line number Diff line
@@ -115,6 +115,8 @@ struct perf_pmu_format { 
	bool loaded;

};



static int pmu_aliases_parse(struct perf_pmu *pmu);



static struct perf_pmu_format *perf_pmu__new_format(struct list_head *list, char *name)

{

	struct perf_pmu_format *format;
@@ -420,10 +422,15 @@ static void perf_pmu__del_aliases(struct perf_pmu *pmu) 
	}

}



static struct perf_pmu_alias *perf_pmu__find_alias(const struct perf_pmu *pmu, const char *name)

static struct perf_pmu_alias *perf_pmu__find_alias(struct perf_pmu *pmu,

						   const char *name,

						   bool load)

{

	struct perf_pmu_alias *alias;



	if (load && !pmu->sysfs_aliases_loaded)

		pmu_aliases_parse(pmu);



	list_for_each_entry(alias, &pmu->aliases, list) {

		if (!strcasecmp(alias->name, name))

			return alias;
@@ -505,7 +512,7 @@ static int perf_pmu__new_alias(struct perf_pmu *pmu, const char *name, 
	const char *long_desc = NULL, *topic = NULL, *unit = NULL, *pmu_name = NULL;

	bool deprecated = false, perpkg = false;



	if (perf_pmu__find_alias(pmu, name)) {

	if (perf_pmu__find_alias(pmu, name, /*load=*/ false)) {

		/* Alias was already created/loaded. */

		return 0;

	}
@@ -611,18 +618,33 @@ static inline bool pmu_alias_info_file(char *name) 
}



/*

 * Process all the sysfs attributes located under the directory

 * specified in 'dir' parameter.

 * Reading the pmu event aliases definition, which should be located at:

 * /sys/bus/event_source/devices/<dev>/events as sysfs group attributes.

 */

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

static int pmu_aliases_parse(struct perf_pmu *pmu)

{

	char path[PATH_MAX];

	struct dirent *evt_ent;

	DIR *event_dir;

	int fd;

	size_t len;

	int fd, dir_fd;



	event_dir = fdopendir(dirfd);

	if (!event_dir)

	len = perf_pmu__event_source_devices_scnprintf(path, sizeof(path));

	if (!len)

		return 0;

	scnprintf(path + len, sizeof(path) - len, "%s/events", pmu->name);



	dir_fd = open(path, O_DIRECTORY);

	if (dir_fd == -1) {

		pmu->sysfs_aliases_loaded = true;

		return 0;

	}



	event_dir = fdopendir(dir_fd);

	if (!event_dir){

		close (dir_fd);

		return -EINVAL;

	}



	while ((evt_ent = readdir(event_dir))) {

		char *name = evt_ent->d_name;
@@ -637,7 +659,7 @@ static int pmu_aliases_parse(struct perf_pmu *pmu, int dirfd) 
		if (pmu_alias_info_file(name))

			continue;



		fd = openat(dirfd, name, O_RDONLY);

		fd = openat(dir_fd, name, O_RDONLY);

		if (fd == -1) {

			pr_debug("Cannot open %s\n", name);

			continue;
@@ -655,25 +677,8 @@ static int pmu_aliases_parse(struct perf_pmu *pmu, int dirfd) 
	}



	closedir(event_dir);

	return 0;

}



/*

 * Reading the pmu event aliases definition, which should be located at:

 * /sys/bus/event_source/devices/<dev>/events as sysfs group attributes.

 */

static int pmu_aliases(struct perf_pmu *pmu, int dirfd, const char *name)

{

	int fd;



	fd = perf_pmu__pathname_fd(dirfd, name, "events", O_DIRECTORY);

	if (fd < 0)

		return 0;



	/* it'll close the fd */

	if (pmu_aliases_parse(pmu, fd))

		return -1;



	close (dir_fd);

	pmu->sysfs_aliases_loaded = true;

	return 0;

}
@@ -1017,13 +1022,6 @@ struct perf_pmu *perf_pmu__lookup(struct list_head *pmus, int dirfd, const char 
		free(pmu);

		return NULL;

	}

	/*

	 * Check the aliases first to avoid unnecessary work.

	 */

	if (pmu_aliases(pmu, dirfd, name)) {

		free(pmu);

		return NULL;

	}

	pmu->is_core = is_pmu_core(name);

	pmu->cpus = pmu_cpumask(dirfd, name, pmu->is_core);
@@ -1438,7 +1436,7 @@ static struct perf_pmu_alias *pmu_find_alias(struct perf_pmu *pmu, 
		return NULL;

	}



	alias = perf_pmu__find_alias(pmu, name);

	alias = perf_pmu__find_alias(pmu, name, /*load=*/ true);

	if (alias || pmu->cpu_aliases_added)

		return alias;
@@ -1447,7 +1445,7 @@ static struct perf_pmu_alias *pmu_find_alias(struct perf_pmu *pmu, 
	    pmu_events_table__find_event(pmu->events_table, pmu, name,

				         pmu_add_cpu_aliases_map_callback,

				         pmu) == 0) {

		alias = perf_pmu__find_alias(pmu, name);

		alias = perf_pmu__find_alias(pmu, name, /*load=*/ false);

	}

	return alias;

}
@@ -1620,7 +1618,7 @@ bool perf_pmu__auto_merge_stats(const struct perf_pmu *pmu) 


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

{

	if (perf_pmu__find_alias(pmu, name) != NULL)

	if (perf_pmu__find_alias(pmu, name, /*load=*/ true) != NULL)

		return true;

	if (pmu->cpu_aliases_added || !pmu->events_table)

		return false;
@@ -1629,7 +1627,12 @@ bool perf_pmu__have_event(struct perf_pmu *pmu, const char *name) 


size_t perf_pmu__num_events(struct perf_pmu *pmu)

{

	size_t nr = pmu->sysfs_aliases;

	size_t nr;



	if (!pmu->sysfs_aliases_loaded)

		pmu_aliases_parse(pmu);



	nr = pmu->sysfs_aliases;



	if (pmu->cpu_aliases_added)

		 nr += pmu->loaded_json_aliases;

tools/perf/util/pmu.h

+2 −0
Original line number Diff line number Diff line
@@ -122,6 +122,8 @@ struct perf_pmu { 
	uint32_t sysfs_aliases;

	/** @sysfs_aliases: Number of json event aliases loaded. */

	uint32_t loaded_json_aliases;

	/** @sysfs_aliases_loaded: Are sysfs aliases loaded from disk? */

	bool sysfs_aliases_loaded;

	/**

	 * @cpu_aliases_added: Have all json events table entries for the PMU

	 * been added?