This is a note to let you know that I've just added the patch titled
perf pmu: Assume sysfs events are always the same case
to the 6.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
perf-pmu-assume-sysfs-events-are-always-the-same-cas.patch
and it can be found in the queue-6.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 2cddc4ec8eaadc37a27f6b1f28a2407ee242d002
Author: Ian Rogers <irogers@xxxxxxxxxx>
Date: Thu May 2 14:35:07 2024 -0700
perf pmu: Assume sysfs events are always the same case
[ Upstream commit 7b6dd7a923281a7ccb980a0f768d6926721eb3cc ]
Perf event names aren't case sensitive. For sysfs events the entire
directory of events is read then iterated comparing names in a case
insensitive way, most often to see if an event is present.
Consider:
$ perf stat -e inst_retired.any true
The event inst_retired.any may be present in any PMU, so every PMU's
sysfs events are loaded and then searched with strcasecmp to see if
any match. This event is only present on the cpu PMU as a JSON event
so a lot of events were loaded from sysfs unnecessarily just to prove
an event didn't exist there.
This change avoids loading all the events by assuming sysfs event
names are always either lower or uppercase. It uses file exists and
only loads the events when the desired event is present.
For the example above, the number of openat calls measured by 'perf
trace' on a tigerlake laptop goes from 325 down to 255. The reduction
will be larger for machines with many PMUs, particularly replicated
uncore PMUs.
Ensure pmu_aliases_parse() is called before all uses of the aliases
list, but remove some "pmu->sysfs_aliases_loaded" tests as they are now
part of the function.
Reviewed-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: James Clark <james.clark@xxxxxxx>
Cc: Jing Zhang <renyu.zj@xxxxxxxxxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Ravi Bangoria <ravi.bangoria@xxxxxxx>
Cc: Thomas Richter <tmricht@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240502213507.2339733-7-irogers@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Stable-dep-of: d9c5f5f94c2d ("perf pmu: Count sys and cpuid JSON events separately")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 8695b47491f0a..feab54606a995 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -425,9 +425,30 @@ static struct perf_pmu_alias *perf_pmu__find_alias(struct perf_pmu *pmu,
{
struct perf_pmu_alias *alias;
- if (load && !pmu->sysfs_aliases_loaded)
- pmu_aliases_parse(pmu);
+ if (load && !pmu->sysfs_aliases_loaded) {
+ bool has_sysfs_event;
+ char event_file_name[FILENAME_MAX + 8];
+ /*
+ * Test if alias/event 'name' exists in the PMU's sysfs/events
+ * directory. If not skip parsing the sysfs aliases. Sysfs event
+ * name must be all lower or all upper case.
+ */
+ scnprintf(event_file_name, sizeof(event_file_name), "events/%s", name);
+ for (size_t i = 7, n = 7 + strlen(name); i < n; i++)
+ event_file_name[i] = tolower(event_file_name[i]);
+
+ has_sysfs_event = perf_pmu__file_exists(pmu, event_file_name);
+ if (!has_sysfs_event) {
+ for (size_t i = 7, n = 7 + strlen(name); i < n; i++)
+ event_file_name[i] = toupper(event_file_name[i]);
+
+ has_sysfs_event = perf_pmu__file_exists(pmu, event_file_name);
+ }
+ if (has_sysfs_event)
+ pmu_aliases_parse(pmu);
+
+ }
list_for_each_entry(alias, &pmu->aliases, list) {
if (!strcasecmp(alias->name, name))
return alias;
@@ -1632,9 +1653,7 @@ size_t perf_pmu__num_events(struct perf_pmu *pmu)
{
size_t nr;
- if (!pmu->sysfs_aliases_loaded)
- pmu_aliases_parse(pmu);
-
+ pmu_aliases_parse(pmu);
nr = pmu->sysfs_aliases;
if (pmu->cpu_aliases_added)
@@ -1693,6 +1712,7 @@ int perf_pmu__for_each_event(struct perf_pmu *pmu, bool skip_duplicate_pmus,
struct strbuf sb;
strbuf_init(&sb, /*hint=*/ 0);
+ pmu_aliases_parse(pmu);
pmu_add_cpu_aliases(pmu);
list_for_each_entry(event, &pmu->aliases, list) {
size_t buf_used;
@@ -2093,6 +2113,7 @@ const char *perf_pmu__name_from_config(struct perf_pmu *pmu, u64 config)
if (!pmu)
return NULL;
+ pmu_aliases_parse(pmu);
pmu_add_cpu_aliases(pmu);
list_for_each_entry(event, &pmu->aliases, list) {
struct perf_event_attr attr = {.config = 0,};
