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Message-Id: <20250207232452.994822-4-irogers@google.com>
Date: Fri, 7 Feb 2025 15:24:44 -0800
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>,
Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>,
Kan Liang <kan.liang@...ux.intel.com>, Sam James <sam@...too.org>,
Jesper Juhl <jesperjuhl76@...il.com>, James Clark <james.clark@...aro.org>,
Zhongqiu Han <quic_zhonhan@...cinc.com>, Yicong Yang <yangyicong@...ilicon.com>,
Thomas Richter <tmricht@...ux.ibm.com>, Michael Petlan <mpetlan@...hat.com>,
Veronika Molnarova <vmolnaro@...hat.com>, Anne Macedo <retpolanne@...teo.net>,
Dominique Martinet <asmadeus@...ewreck.org>,
Jean-Philippe Romain <jean-philippe.romain@...s.st.com>, Junhao He <hejunhao3@...wei.com>,
linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
"Krzysztof Łopatowski" <krzysztof.m.lopatowski@...il.com>
Subject: [PATCH v2 3/7] perf pmu: Switch to io_dir__readdir
Avoid DIR allocations when scanning sysfs by using io_dir for the
readdir implementation, that allocates about 1kb on the stack.
Acked-by: Namhyung Kim <namhyung@...nel.org>
Signed-off-by: Ian Rogers <irogers@...gle.com>
---
tools/perf/util/pmu.c | 46 +++++++++++++++++-------------------------
tools/perf/util/pmus.c | 30 ++++++++++-----------------
2 files changed, 30 insertions(+), 46 deletions(-)
diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index c2a15b0259cf..91ed909433cc 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -13,6 +13,7 @@
#include <dirent.h>
#include <api/fs/fs.h>
#include <api/io.h>
+#include <api/io_dir.h>
#include <locale.h>
#include <fnmatch.h>
#include <math.h>
@@ -195,19 +196,17 @@ static void perf_pmu_format__load(const struct perf_pmu *pmu, struct perf_pmu_fo
*/
static int perf_pmu__format_parse(struct perf_pmu *pmu, int dirfd, bool eager_load)
{
- struct dirent *evt_ent;
- DIR *format_dir;
+ struct io_dirent64 *evt_ent;
+ struct io_dir format_dir;
int ret = 0;
- format_dir = fdopendir(dirfd);
- if (!format_dir)
- return -EINVAL;
+ io_dir__init(&format_dir, dirfd);
- while ((evt_ent = readdir(format_dir)) != NULL) {
+ while ((evt_ent = io_dir__readdir(&format_dir)) != NULL) {
struct perf_pmu_format *format;
char *name = evt_ent->d_name;
- if (!strcmp(name, ".") || !strcmp(name, ".."))
+ if (io_dir__is_dir(&format_dir, evt_ent))
continue;
format = perf_pmu__new_format(&pmu->format, name);
@@ -234,7 +233,7 @@ static int perf_pmu__format_parse(struct perf_pmu *pmu, int dirfd, bool eager_lo
}
}
- closedir(format_dir);
+ close(format_dir.dirfd);
return ret;
}
@@ -635,14 +634,12 @@ static inline bool pmu_alias_info_file(const char *name)
*/
static int __pmu_aliases_parse(struct perf_pmu *pmu, int events_dir_fd)
{
- struct dirent *evt_ent;
- DIR *event_dir;
+ struct io_dirent64 *evt_ent;
+ struct io_dir event_dir;
- event_dir = fdopendir(events_dir_fd);
- if (!event_dir)
- return -EINVAL;
+ io_dir__init(&event_dir, events_dir_fd);
- while ((evt_ent = readdir(event_dir))) {
+ while ((evt_ent = io_dir__readdir(&event_dir))) {
char *name = evt_ent->d_name;
int fd;
FILE *file;
@@ -674,7 +671,6 @@ static int __pmu_aliases_parse(struct perf_pmu *pmu, int events_dir_fd)
fclose(file);
}
- closedir(event_dir);
pmu->sysfs_aliases_loaded = true;
return 0;
}
@@ -2221,10 +2217,9 @@ static void perf_pmu__del_caps(struct perf_pmu *pmu)
*/
int perf_pmu__caps_parse(struct perf_pmu *pmu)
{
- struct stat st;
char caps_path[PATH_MAX];
- DIR *caps_dir;
- struct dirent *evt_ent;
+ struct io_dir caps_dir;
+ struct io_dirent64 *evt_ent;
int caps_fd;
if (pmu->caps_initialized)
@@ -2235,24 +2230,21 @@ int perf_pmu__caps_parse(struct perf_pmu *pmu)
if (!perf_pmu__pathname_scnprintf(caps_path, sizeof(caps_path), pmu->name, "caps"))
return -1;
- if (stat(caps_path, &st) < 0) {
+ caps_fd = open(caps_path, O_CLOEXEC | O_DIRECTORY | O_RDONLY);
+ if (caps_fd == -1) {
pmu->caps_initialized = true;
return 0; /* no error if caps does not exist */
}
- caps_dir = opendir(caps_path);
- if (!caps_dir)
- return -EINVAL;
-
- caps_fd = dirfd(caps_dir);
+ io_dir__init(&caps_dir, caps_fd);
- while ((evt_ent = readdir(caps_dir)) != NULL) {
+ while ((evt_ent = io_dir__readdir(&caps_dir)) != NULL) {
char *name = evt_ent->d_name;
char value[128];
FILE *file;
int fd;
- if (!strcmp(name, ".") || !strcmp(name, ".."))
+ if (io_dir__is_dir(&caps_dir, evt_ent))
continue;
fd = openat(caps_fd, name, O_RDONLY);
@@ -2274,7 +2266,7 @@ int perf_pmu__caps_parse(struct perf_pmu *pmu)
fclose(file);
}
- closedir(caps_dir);
+ close(caps_fd);
pmu->caps_initialized = true;
return pmu->nr_caps;
diff --git a/tools/perf/util/pmus.c b/tools/perf/util/pmus.c
index 8a0a919415d4..afd59d678fd0 100644
--- a/tools/perf/util/pmus.c
+++ b/tools/perf/util/pmus.c
@@ -3,10 +3,10 @@
#include <linux/list_sort.h>
#include <linux/string.h>
#include <linux/zalloc.h>
+#include <api/io_dir.h>
#include <subcmd/pager.h>
#include <sys/types.h>
#include <ctype.h>
-#include <dirent.h>
#include <pthread.h>
#include <string.h>
#include <unistd.h>
@@ -235,20 +235,16 @@ static void pmu_read_sysfs(unsigned int to_read_types)
if (to_read_types & (PERF_TOOL_PMU_TYPE_PE_CORE_MASK | PERF_TOOL_PMU_TYPE_PE_OTHER_MASK)) {
int fd = perf_pmu__event_source_devices_fd();
- DIR *dir;
- struct dirent *dent;
+ struct io_dir dir;
+ struct io_dirent64 *dent;
bool core_only = (to_read_types & PERF_TOOL_PMU_TYPE_PE_OTHER_MASK) == 0;
if (fd < 0)
goto skip_pe_pmus;
- dir = fdopendir(fd);
- if (!dir) {
- close(fd);
- goto skip_pe_pmus;
- }
+ io_dir__init(&dir, fd);
- while ((dent = readdir(dir))) {
+ while ((dent = io_dir__readdir(&dir)) != NULL) {
if (!strcmp(dent->d_name, ".") || !strcmp(dent->d_name, ".."))
continue;
if (core_only && !is_pmu_core(dent->d_name))
@@ -257,7 +253,7 @@ static void pmu_read_sysfs(unsigned int to_read_types)
perf_pmu__find2(fd, dent->d_name);
}
- closedir(dir);
+ close(fd);
}
skip_pe_pmus:
if ((to_read_types & PERF_TOOL_PMU_TYPE_PE_CORE_MASK) && list_empty(&core_pmus)) {
@@ -721,8 +717,8 @@ bool perf_pmus__supports_extended_type(void)
char *perf_pmus__default_pmu_name(void)
{
int fd;
- DIR *dir;
- struct dirent *dent;
+ struct io_dir dir;
+ struct io_dirent64 *dent;
char *result = NULL;
if (!list_empty(&core_pmus))
@@ -732,13 +728,9 @@ char *perf_pmus__default_pmu_name(void)
if (fd < 0)
return strdup("cpu");
- dir = fdopendir(fd);
- if (!dir) {
- close(fd);
- return strdup("cpu");
- }
+ io_dir__init(&dir, fd);
- while ((dent = readdir(dir))) {
+ while ((dent = io_dir__readdir(&dir)) != NULL) {
if (!strcmp(dent->d_name, ".") || !strcmp(dent->d_name, ".."))
continue;
if (is_pmu_core(dent->d_name)) {
@@ -747,7 +739,7 @@ char *perf_pmus__default_pmu_name(void)
}
}
- closedir(dir);
+ close(fd);
return result ?: strdup("cpu");
}
--
2.48.1.502.g6dc24dfdaf-goog
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