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Message-Id: <20230824041330.266337-17-irogers@google.com>
Date: Wed, 23 Aug 2023 21:13:28 -0700
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>,
James Clark <james.clark@....com>,
Kan Liang <kan.liang@...ux.intel.com>,
John Garry <john.g.garry@...cle.com>,
Kajol Jain <kjain@...ux.ibm.com>,
Jing Zhang <renyu.zj@...ux.alibaba.com>,
Ravi Bangoria <ravi.bangoria@....com>,
Rob Herring <robh@...nel.org>,
Gaosheng Cui <cuigaosheng1@...wei.com>,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 16/18] 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: Ian Rogers <irogers@...gle.com>
---
tools/perf/tests/pmu-events.c | 2 +
tools/perf/util/pmu.c | 81 ++++++++++++++++++-----------------
tools/perf/util/pmu.h | 2 +
3 files changed, 46 insertions(+), 39 deletions(-)
diff --git a/tools/perf/tests/pmu-events.c b/tools/perf/tests/pmu-events.c
index 9ac893ae5f0d..3dc1ebee4d9f 100644
--- a/tools/perf/tests/pmu-events.c
+++ b/tools/perf/tests/pmu-events.c
@@ -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 */
diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 493d3e59fd50..bb2ca29cd7bd 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -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;
diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
index 288d2908382a..bae0de3ed7a5 100644
--- a/tools/perf/util/pmu.h
+++ b/tools/perf/util/pmu.h
@@ -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?
--
2.42.0.rc1.204.g551eb34607-goog
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