glibc's opendir allocates a minimum of 32kb, when called recursively
for a directory tree the memory consumption can add up - nearly 300kb
during perf start-up when processing modules. Add a stack allocated
variant of readdir sized a little more than 1kb
This was previously part of the memory saving change set:
https://lore.kernel.org/lkml/[email protected]/
It is separated here and a feature check and syscall workaround for
missing getdents64 added.
Ian Rogers (6):
tools build: Add a feature test for getdents64
tools lib api: Add io_dir an allocation free readdir alternative
perf maps: Switch modules tree walk to io_dir__readdir
perf pmu: Switch to io_dir__readdir
perf header: Switch mem topology to io_dir__readdir
perf events: Remove scandir in thread synthesis
tools/build/Makefile.feature | 1 +
tools/build/feature/Makefile | 4 ++
tools/build/feature/test-all.c | 5 ++
tools/build/feature/test-getdents64.c | 12 ++++
tools/lib/api/Makefile | 2 +-
tools/lib/api/io_dir.h | 84 +++++++++++++++++++++++++++
tools/perf/Makefile.config | 4 ++
tools/perf/util/header.c | 31 +++++-----
tools/perf/util/machine.c | 19 +++---
tools/perf/util/pmu.c | 48 ++++++---------
tools/perf/util/pmus.c | 30 ++++------
tools/perf/util/synthetic-events.c | 22 +++----
12 files changed, 177 insertions(+), 85 deletions(-)
create mode 100644 tools/build/feature/test-getdents64.c
create mode 100644 tools/lib/api/io_dir.h
--
2.43.0.rc2.451.g8631bc7472-goog
getdents64 may be missing from certain libcs, add a feature test to
determine when such a libc is being used.
Signed-off-by: Ian Rogers <[email protected]>
---
tools/build/Makefile.feature | 1 +
tools/build/feature/Makefile | 4 ++++
tools/build/feature/test-all.c | 5 +++++
tools/build/feature/test-getdents64.c | 12 ++++++++++++
4 files changed, 22 insertions(+)
create mode 100644 tools/build/feature/test-getdents64.c
diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
index 64df118376df..f051d4d8c71c 100644
--- a/tools/build/Makefile.feature
+++ b/tools/build/Makefile.feature
@@ -58,6 +58,7 @@ FEATURE_TESTS_BASIC := \
pthread-attr-setaffinity-np \
pthread-barrier \
reallocarray \
+ getdents64 \
stackprotector-all \
timerfd \
libdw-dwarf-unwind \
diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index 37722e509eb9..5efe89c3b0a6 100644
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -21,6 +21,7 @@ FILES= \
test-disassembler-four-args.bin \
test-disassembler-init-styled.bin \
test-reallocarray.bin \
+ test-getdents64.bin \
test-libbfd-liberty.bin \
test-libbfd-liberty-z.bin \
test-cplus-demangle.bin \
@@ -262,6 +263,9 @@ $(OUTPUT)test-disassembler-init-styled.bin:
$(OUTPUT)test-reallocarray.bin:
$(BUILD)
+$(OUTPUT)test-getdents64.bin:
+ $(BUILD)
+
$(OUTPUT)test-libbfd-liberty.bin:
$(CC) $(CFLAGS) -Wall -Werror -o $@ test-libbfd.c -DPACKAGE='"perf"' $(LDFLAGS) -lbfd -ldl -liberty
diff --git a/tools/build/feature/test-all.c b/tools/build/feature/test-all.c
index 6f4bf386a3b5..c65096f75032 100644
--- a/tools/build/feature/test-all.c
+++ b/tools/build/feature/test-all.c
@@ -166,6 +166,10 @@
# include "test-reallocarray.c"
#undef main
+#define main main_test_getdents64
+# include "test-getdents64.c"
+#undef main
+
#define main main_test_disassembler_four_args
# include "test-disassembler-four-args.c"
#undef main
@@ -216,6 +220,7 @@ int main(int argc, char *argv[])
main_test_setns();
main_test_libaio();
main_test_reallocarray();
+ main_test_getdents64();
main_test_disassembler_four_args();
main_test_libzstd();
diff --git a/tools/build/feature/test-getdents64.c b/tools/build/feature/test-getdents64.c
new file mode 100644
index 000000000000..f7c9df1e2f05
--- /dev/null
+++ b/tools/build/feature/test-getdents64.c
@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stddef.h>
+#define _GNU_SOURCE
+#include <dirent.h>
+
+int main(void)
+{
+ char buf[128];
+ return (int)getdents64(0, buf, sizeof(buf));
+}
+
+#undef _GNU_SOURCE
--
2.43.0.rc2.451.g8631bc7472-goog
glibc's opendir allocates a minimum of 32kb, when called recursively
for a directory tree the memory consumption can add up - nearly 300kb
during perf start-up when processing modules. Add a stack allocated
variant of readdir sized a little more than 1kb.
As getdents64 may be missing from libc, add support using syscall.
Signed-off-by: Ian Rogers <[email protected]>
---
tools/lib/api/Makefile | 2 +-
tools/lib/api/io_dir.h | 84 ++++++++++++++++++++++++++++++++++++++
tools/perf/Makefile.config | 4 ++
3 files changed, 89 insertions(+), 1 deletion(-)
create mode 100644 tools/lib/api/io_dir.h
diff --git a/tools/lib/api/Makefile b/tools/lib/api/Makefile
index 044860ac1ed1..186aa407de8c 100644
--- a/tools/lib/api/Makefile
+++ b/tools/lib/api/Makefile
@@ -99,7 +99,7 @@ install_lib: $(LIBFILE)
$(call do_install_mkdir,$(libdir_SQ)); \
cp -fpR $(LIBFILE) $(DESTDIR)$(libdir_SQ)
-HDRS := cpu.h debug.h io.h
+HDRS := cpu.h debug.h io.h io_dir.h
FD_HDRS := fd/array.h
FS_HDRS := fs/fs.h fs/tracing_path.h
INSTALL_HDRS_PFX := $(DESTDIR)$(prefix)/include/api
diff --git a/tools/lib/api/io_dir.h b/tools/lib/api/io_dir.h
new file mode 100644
index 000000000000..9b702497e05c
--- /dev/null
+++ b/tools/lib/api/io_dir.h
@@ -0,0 +1,84 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+/*
+ * Lightweight directory reading library.
+ */
+#ifndef __API_IO_DIR__
+#define __API_IO_DIR__
+
+#include <dirent.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/stat.h>
+
+#ifndef HAVE_GETDENTS64
+#include <sys/syscall.h>
+
+static inline ssize_t getdents64(int fd, void *dirp, size_t count)
+{
+ return syscall(SYS_getdents64, fd, dirp, count);
+}
+#endif
+
+struct io_dirent64 {
+ ino64_t d_ino; /* 64-bit inode number */
+ off64_t d_off; /* 64-bit offset to next structure */
+ unsigned short d_reclen; /* Size of this dirent */
+ unsigned char d_type; /* File type */
+ char d_name[NAME_MAX + 1]; /* Filename (null-terminated) */
+};
+
+struct io_dir {
+ int dirfd;
+ ssize_t available_bytes;
+ struct io_dirent64 *next;
+ struct io_dirent64 buff[4];
+};
+
+static inline void io_dir__init(struct io_dir *iod, int dirfd)
+{
+ iod->dirfd = dirfd;
+ iod->available_bytes = 0;
+}
+
+static inline void io_dir__rewinddir(struct io_dir *iod)
+{
+ lseek(iod->dirfd, 0, SEEK_SET);
+ iod->available_bytes = 0;
+}
+
+static inline struct io_dirent64 *io_dir__readdir(struct io_dir *iod)
+{
+ struct io_dirent64 *entry;
+
+ if (iod->available_bytes <= 0) {
+ ssize_t rc = getdents64(iod->dirfd, iod->buff, sizeof(iod->buff));
+
+ if (rc <= 0)
+ return NULL;
+ iod->available_bytes = rc;
+ iod->next = iod->buff;
+ }
+ entry = iod->next;
+ iod->next = (struct io_dirent64 *)((char *)entry + entry->d_reclen);
+ iod->available_bytes -= entry->d_reclen;
+ return entry;
+}
+
+static inline bool io_dir__is_dir(const struct io_dir *iod, struct io_dirent64 *dent)
+{
+ if (dent->d_type == DT_UNKNOWN) {
+ struct stat st;
+
+ if (fstatat(iod->dirfd, dent->d_name, &st, /*flags=*/0))
+ return false;
+
+ if (S_ISDIR(st.st_mode)) {
+ dent->d_type = DT_DIR;
+ return true;
+ }
+ }
+ return dent->d_type == DT_DIR;
+}
+
+#endif
diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index aa55850fbc21..1cef1ab4ddb7 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -357,6 +357,10 @@ ifeq ($(feature-stackprotector-all), 1)
CORE_CFLAGS += -fstack-protector-all
endif
+ifeq ($(feature-getdents64), 1)
+ CFLAGS += -DHAVE_GETDENTS64
+endif
+
ifeq ($(DEBUG),0)
ifeq ($(feature-fortify-source), 1)
CORE_CFLAGS += -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2
--
2.43.0.rc2.451.g8631bc7472-goog
Compared to glibc's opendir/readdir this lowers the max RSS of perf
record by 1.8MB on a Debian machine.
Signed-off-by: Ian Rogers <[email protected]>
---
tools/perf/util/machine.c | 19 ++++++++-----------
1 file changed, 8 insertions(+), 11 deletions(-)
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index c5de5363b5e7..b6831a1f909d 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -36,6 +36,7 @@
#include <internal/lib.h> // page_size
#include "cgroup.h"
#include "arm64-frame-pointer-unwind-support.h"
+#include <api/io_dir.h>
#include <linux/ctype.h>
#include <symbol/kallsyms.h>
@@ -1551,25 +1552,21 @@ static int maps__set_module_path(struct maps *maps, const char *path, struct kmo
static int maps__set_modules_path_dir(struct maps *maps, const char *dir_name, int depth)
{
- struct dirent *dent;
- DIR *dir = opendir(dir_name);
+ struct io_dirent64 *dent;
+ struct io_dir iod;
int ret = 0;
- if (!dir) {
+ io_dir__init(&iod, open(dir_name, O_CLOEXEC | O_DIRECTORY | O_RDONLY));
+ if (iod.dirfd < 0) {
pr_debug("%s: cannot open %s dir\n", __func__, dir_name);
return -1;
}
- while ((dent = readdir(dir)) != NULL) {
+ while ((dent = io_dir__readdir(&iod)) != NULL) {
char path[PATH_MAX];
- struct stat st;
- /*sshfs might return bad dent->d_type, so we have to stat*/
path__join(path, sizeof(path), dir_name, dent->d_name);
- if (stat(path, &st))
- continue;
-
- if (S_ISDIR(st.st_mode)) {
+ if (io_dir__is_dir(&iod, dent)) {
if (!strcmp(dent->d_name, ".") ||
!strcmp(dent->d_name, ".."))
continue;
@@ -1602,7 +1599,7 @@ static int maps__set_modules_path_dir(struct maps *maps, const char *dir_name, i
}
out:
- closedir(dir);
+ close(iod.dirfd);
return ret;
}
--
2.43.0.rc2.451.g8631bc7472-goog
Switch memory_node__read and build_mem_topology from opendir/readdir
to io_dir__readdir, with smaller stack allocations. Reduces peak
memory consumption of perf record by 10kb.
Signed-off-by: Ian Rogers <[email protected]>
---
tools/perf/util/header.c | 31 ++++++++++++++++---------------
1 file changed, 16 insertions(+), 15 deletions(-)
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 08cc2febabde..d4a3e28376fd 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -44,6 +44,7 @@
#include "build-id.h"
#include "data.h"
#include <api/fs/fs.h>
+#include <api/io_dir.h>
#include "asm/bug.h"
#include "tool.h"
#include "time-utils.h"
@@ -1341,11 +1342,11 @@ static int memory_node__read(struct memory_node *n, unsigned long idx)
{
unsigned int phys, size = 0;
char path[PATH_MAX];
- struct dirent *ent;
- DIR *dir;
+ struct io_dirent64 *ent;
+ struct io_dir dir;
#define for_each_memory(mem, dir) \
- while ((ent = readdir(dir))) \
+ while ((ent = io_dir__readdir(&dir)) != NULL) \
if (strcmp(ent->d_name, ".") && \
strcmp(ent->d_name, "..") && \
sscanf(ent->d_name, "memory%u", &mem) == 1)
@@ -1354,9 +1355,9 @@ static int memory_node__read(struct memory_node *n, unsigned long idx)
"%s/devices/system/node/node%lu",
sysfs__mountpoint(), idx);
- dir = opendir(path);
- if (!dir) {
- pr_warning("failed: can't open memory sysfs data\n");
+ io_dir__init(&dir, open(path, O_CLOEXEC | O_DIRECTORY | O_RDONLY));
+ if (dir.dirfd < 0) {
+ pr_warning("failed: can't open memory sysfs data '%s'\n", path);
return -1;
}
@@ -1368,20 +1369,20 @@ static int memory_node__read(struct memory_node *n, unsigned long idx)
n->set = bitmap_zalloc(size);
if (!n->set) {
- closedir(dir);
+ close(dir.dirfd);
return -ENOMEM;
}
n->node = idx;
n->size = size;
- rewinddir(dir);
+ io_dir__rewinddir(&dir);
for_each_memory(phys, dir) {
__set_bit(phys, n->set);
}
- closedir(dir);
+ close(dir.dirfd);
return 0;
}
@@ -1404,8 +1405,8 @@ static int memory_node__sort(const void *a, const void *b)
static int build_mem_topology(struct memory_node **nodesp, u64 *cntp)
{
char path[PATH_MAX];
- struct dirent *ent;
- DIR *dir;
+ struct io_dirent64 *ent;
+ struct io_dir dir;
int ret = 0;
size_t cnt = 0, size = 0;
struct memory_node *nodes = NULL;
@@ -1413,14 +1414,14 @@ static int build_mem_topology(struct memory_node **nodesp, u64 *cntp)
scnprintf(path, PATH_MAX, "%s/devices/system/node/",
sysfs__mountpoint());
- dir = opendir(path);
- if (!dir) {
+ io_dir__init(&dir, open(path, O_CLOEXEC | O_DIRECTORY | O_RDONLY));
+ if (dir.dirfd < 0) {
pr_debug2("%s: couldn't read %s, does this arch have topology information?\n",
__func__, path);
return -1;
}
- while (!ret && (ent = readdir(dir))) {
+ while (!ret && (ent = io_dir__readdir(&dir))) {
unsigned int idx;
int r;
@@ -1449,7 +1450,7 @@ static int build_mem_topology(struct memory_node **nodesp, u64 *cntp)
cnt += 1;
}
out:
- closedir(dir);
+ close(dir.dirfd);
if (!ret) {
*cntp = cnt;
*nodesp = nodes;
--
2.43.0.rc2.451.g8631bc7472-goog
Avoid DIR allocations when scanning sysfs by using io_dir for the
readdir implementation, that allocates about 1kb on the stack.
Signed-off-by: Ian Rogers <[email protected]>
---
tools/perf/util/pmu.c | 48 +++++++++++++++++-------------------------
tools/perf/util/pmus.c | 30 ++++++++++----------------
2 files changed, 30 insertions(+), 48 deletions(-)
diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 3c9609944a2f..cddb82123a1e 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -12,6 +12,7 @@
#include <stdbool.h>
#include <dirent.h>
#include <api/fs/fs.h>
+#include <api/io_dir.h>
#include <locale.h>
#include <fnmatch.h>
#include <math.h>
@@ -184,19 +185,17 @@ static void perf_pmu_format__load(const struct perf_pmu *pmu, struct perf_pmu_fo
*/
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);
@@ -223,7 +222,7 @@ int perf_pmu__format_parse(struct perf_pmu *pmu, int dirfd, bool eager_load)
}
}
- closedir(format_dir);
+ close(format_dir.dirfd);
return ret;
}
@@ -599,8 +598,8 @@ static inline bool pmu_alias_info_file(const char *name)
static int pmu_aliases_parse(struct perf_pmu *pmu)
{
char path[PATH_MAX];
- struct dirent *evt_ent;
- DIR *event_dir;
+ struct io_dirent64 *evt_ent;
+ struct io_dir event_dir;
size_t len;
int fd, dir_fd;
@@ -615,13 +614,9 @@ static int pmu_aliases_parse(struct perf_pmu *pmu)
return 0;
}
- event_dir = fdopendir(dir_fd);
- if (!event_dir){
- close (dir_fd);
- return -EINVAL;
- }
+ io_dir__init(&event_dir, dir_fd);
- while ((evt_ent = readdir(event_dir))) {
+ while ((evt_ent = io_dir__readdir(&event_dir))) {
char *name = evt_ent->d_name;
FILE *file;
@@ -651,7 +646,6 @@ static int pmu_aliases_parse(struct perf_pmu *pmu)
fclose(file);
}
- closedir(event_dir);
close (dir_fd);
pmu->sysfs_aliases_loaded = true;
return 0;
@@ -1883,10 +1877,9 @@ 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)
@@ -1897,24 +1890,21 @@ 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);
@@ -1936,7 +1926,7 @@ 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 ce4931461741..65b23b98666b 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>
@@ -184,8 +184,8 @@ static int pmus_cmp(void *priv __maybe_unused,
static void pmu_read_sysfs(bool core_only)
{
int fd;
- DIR *dir;
- struct dirent *dent;
+ struct io_dir dir;
+ struct io_dirent64 *dent;
if (read_sysfs_all_pmus || (core_only && read_sysfs_core_pmus))
return;
@@ -194,13 +194,9 @@ static void pmu_read_sysfs(bool core_only)
if (fd < 0)
return;
- dir = fdopendir(fd);
- if (!dir) {
- close(fd);
- return;
- }
+ 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))
@@ -209,7 +205,7 @@ static void pmu_read_sysfs(bool core_only)
perf_pmu__find2(fd, dent->d_name);
}
- closedir(dir);
+ close(fd);
if (list_empty(&core_pmus)) {
if (!perf_pmu__create_placeholder_core_pmu(&core_pmus))
pr_err("Failure to set up any core PMUs\n");
@@ -563,8 +559,8 @@ 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))
@@ -574,13 +570,9 @@ 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)) {
@@ -589,7 +581,7 @@ char *perf_pmus__default_pmu_name(void)
}
}
- closedir(dir);
+ close(fd);
return result ?: strdup("cpu");
}
--
2.43.0.rc2.451.g8631bc7472-goog
This avoids scanddir reading the directory into memory that's
allocated and instead allocates on the stack.
Signed-off-by: Ian Rogers <[email protected]>
---
tools/perf/util/synthetic-events.c | 22 ++++++++++++----------
1 file changed, 12 insertions(+), 10 deletions(-)
diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index a0579c7d7b9e..7cc38f2a0e9e 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -38,6 +38,7 @@
#include <uapi/linux/mman.h> /* To get things like MAP_HUGETLB even on older libc headers */
#include <api/fs/fs.h>
#include <api/io.h>
+#include <api/io_dir.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
@@ -751,10 +752,10 @@ static int __event__synthesize_thread(union perf_event *comm_event,
bool needs_mmap, bool mmap_data)
{
char filename[PATH_MAX];
- struct dirent **dirent;
+ struct io_dir iod;
+ struct io_dirent64 *dent;
pid_t tgid, ppid;
int rc = 0;
- int i, n;
/* special case: only send one comm event using passed in pid */
if (!full) {
@@ -786,16 +787,19 @@ static int __event__synthesize_thread(union perf_event *comm_event,
snprintf(filename, sizeof(filename), "%s/proc/%d/task",
machine->root_dir, pid);
- n = scandir(filename, &dirent, filter_task, NULL);
- if (n < 0)
- return n;
+ io_dir__init(&iod, open(filename, O_CLOEXEC | O_DIRECTORY | O_RDONLY));
+ if (iod.dirfd < 0)
+ return -1;
- for (i = 0; i < n; i++) {
+ while ((dent = io_dir__readdir(&iod)) != NULL) {
char *end;
pid_t _pid;
bool kernel_thread = false;
- _pid = strtol(dirent[i]->d_name, &end, 10);
+ if (!isdigit(dent->d_name[0]))
+ continue;
+
+ _pid = strtol(dent->d_name, &end, 10);
if (*end)
continue;
@@ -829,9 +833,7 @@ static int __event__synthesize_thread(union perf_event *comm_event,
}
}
- for (i = 0; i < n; i++)
- zfree(&dirent[i]);
- free(dirent);
+ close(iod.dirfd);
return rc;
}
--
2.43.0.rc2.451.g8631bc7472-goog
On Wed, Dec 6, 2023 at 9:04 PM Ian Rogers <[email protected]> wrote:
>
> glibc's opendir allocates a minimum of 32kb, when called recursively
> for a directory tree the memory consumption can add up - nearly 300kb
> during perf start-up when processing modules. Add a stack allocated
> variant of readdir sized a little more than 1kb.
>
> As getdents64 may be missing from libc, add support using syscall.
Unfortunately my alpine build has:
In file included from util/machine.c:2:
/build/libapi/include/api/io_dir.h:17:23: error: conflicting types for
'getdents'; have 'ssize_t(int, void *, size_t)' {aka 'long int(int,
void *, long unsigned int)'}
17 | static inline ssize_t getdents64(int fd, void *dirp, size_t count)
| ^~~~~~~~~~
/usr/include/dirent.h:52:5: note: previous declaration of 'getdents'
with type 'int(int, struct dirent *, size_t)' {aka 'int(int, struct
dirent *, long unsigned int)'}
52 | int getdents(int, struct dirent *, size_t);
| ^~~~~~~~
Thanks,
Namhyung
>
> Signed-off-by: Ian Rogers <[email protected]>
> ---
> tools/lib/api/Makefile | 2 +-
> tools/lib/api/io_dir.h | 84 ++++++++++++++++++++++++++++++++++++++
> tools/perf/Makefile.config | 4 ++
> 3 files changed, 89 insertions(+), 1 deletion(-)
> create mode 100644 tools/lib/api/io_dir.h
>
> diff --git a/tools/lib/api/Makefile b/tools/lib/api/Makefile
> index 044860ac1ed1..186aa407de8c 100644
> --- a/tools/lib/api/Makefile
> +++ b/tools/lib/api/Makefile
> @@ -99,7 +99,7 @@ install_lib: $(LIBFILE)
> $(call do_install_mkdir,$(libdir_SQ)); \
> cp -fpR $(LIBFILE) $(DESTDIR)$(libdir_SQ)
>
> -HDRS := cpu.h debug.h io.h
> +HDRS := cpu.h debug.h io.h io_dir.h
> FD_HDRS := fd/array.h
> FS_HDRS := fs/fs.h fs/tracing_path.h
> INSTALL_HDRS_PFX := $(DESTDIR)$(prefix)/include/api
> diff --git a/tools/lib/api/io_dir.h b/tools/lib/api/io_dir.h
> new file mode 100644
> index 000000000000..9b702497e05c
> --- /dev/null
> +++ b/tools/lib/api/io_dir.h
> @@ -0,0 +1,84 @@
> +/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
> +/*
> + * Lightweight directory reading library.
> + */
> +#ifndef __API_IO_DIR__
> +#define __API_IO_DIR__
> +
> +#include <dirent.h>
> +#include <fcntl.h>
> +#include <stdlib.h>
> +#include <unistd.h>
> +#include <sys/stat.h>
> +
> +#ifndef HAVE_GETDENTS64
> +#include <sys/syscall.h>
> +
> +static inline ssize_t getdents64(int fd, void *dirp, size_t count)
> +{
> + return syscall(SYS_getdents64, fd, dirp, count);
> +}
> +#endif
> +
> +struct io_dirent64 {
> + ino64_t d_ino; /* 64-bit inode number */
> + off64_t d_off; /* 64-bit offset to next structure */
> + unsigned short d_reclen; /* Size of this dirent */
> + unsigned char d_type; /* File type */
> + char d_name[NAME_MAX + 1]; /* Filename (null-terminated) */
> +};
> +
> +struct io_dir {
> + int dirfd;
> + ssize_t available_bytes;
> + struct io_dirent64 *next;
> + struct io_dirent64 buff[4];
> +};
> +
> +static inline void io_dir__init(struct io_dir *iod, int dirfd)
> +{
> + iod->dirfd = dirfd;
> + iod->available_bytes = 0;
> +}
> +
> +static inline void io_dir__rewinddir(struct io_dir *iod)
> +{
> + lseek(iod->dirfd, 0, SEEK_SET);
> + iod->available_bytes = 0;
> +}
> +
> +static inline struct io_dirent64 *io_dir__readdir(struct io_dir *iod)
> +{
> + struct io_dirent64 *entry;
> +
> + if (iod->available_bytes <= 0) {
> + ssize_t rc = getdents64(iod->dirfd, iod->buff, sizeof(iod->buff));
> +
> + if (rc <= 0)
> + return NULL;
> + iod->available_bytes = rc;
> + iod->next = iod->buff;
> + }
> + entry = iod->next;
> + iod->next = (struct io_dirent64 *)((char *)entry + entry->d_reclen);
> + iod->available_bytes -= entry->d_reclen;
> + return entry;
> +}
> +
> +static inline bool io_dir__is_dir(const struct io_dir *iod, struct io_dirent64 *dent)
> +{
> + if (dent->d_type == DT_UNKNOWN) {
> + struct stat st;
> +
> + if (fstatat(iod->dirfd, dent->d_name, &st, /*flags=*/0))
> + return false;
> +
> + if (S_ISDIR(st.st_mode)) {
> + dent->d_type = DT_DIR;
> + return true;
> + }
> + }
> + return dent->d_type == DT_DIR;
> +}
> +
> +#endif
> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> index aa55850fbc21..1cef1ab4ddb7 100644
> --- a/tools/perf/Makefile.config
> +++ b/tools/perf/Makefile.config
> @@ -357,6 +357,10 @@ ifeq ($(feature-stackprotector-all), 1)
> CORE_CFLAGS += -fstack-protector-all
> endif
>
> +ifeq ($(feature-getdents64), 1)
> + CFLAGS += -DHAVE_GETDENTS64
> +endif
> +
> ifeq ($(DEBUG),0)
> ifeq ($(feature-fortify-source), 1)
> CORE_CFLAGS += -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2
> --
> 2.43.0.rc2.451.g8631bc7472-goog
>
On Mon, Dec 11, 2023 at 3:25 PM Namhyung Kim <[email protected]> wrote:
>
> On Wed, Dec 6, 2023 at 9:04 PM Ian Rogers <[email protected]> wrote:
> >
> > glibc's opendir allocates a minimum of 32kb, when called recursively
> > for a directory tree the memory consumption can add up - nearly 300kb
> > during perf start-up when processing modules. Add a stack allocated
> > variant of readdir sized a little more than 1kb.
> >
> > As getdents64 may be missing from libc, add support using syscall.
>
> Unfortunately my alpine build has:
>
> In file included from util/machine.c:2:
> /build/libapi/include/api/io_dir.h:17:23: error: conflicting types for
> 'getdents'; have 'ssize_t(int, void *, size_t)' {aka 'long int(int,
> void *, long unsigned int)'}
> 17 | static inline ssize_t getdents64(int fd, void *dirp, size_t count)
> | ^~~~~~~~~~
> /usr/include/dirent.h:52:5: note: previous declaration of 'getdents'
> with type 'int(int, struct dirent *, size_t)' {aka 'int(int, struct
> dirent *, long unsigned int)'}
> 52 | int getdents(int, struct dirent *, size_t);
> | ^~~~~~~~
Presumably there is a #define getdents64 getdents .. Could we stop
caring about this version of Alpine linux?
Thanks,
Ian
> Thanks,
> Namhyung
>
> >
> > Signed-off-by: Ian Rogers <[email protected]>
> > ---
> > tools/lib/api/Makefile | 2 +-
> > tools/lib/api/io_dir.h | 84 ++++++++++++++++++++++++++++++++++++++
> > tools/perf/Makefile.config | 4 ++
> > 3 files changed, 89 insertions(+), 1 deletion(-)
> > create mode 100644 tools/lib/api/io_dir.h
> >
> > diff --git a/tools/lib/api/Makefile b/tools/lib/api/Makefile
> > index 044860ac1ed1..186aa407de8c 100644
> > --- a/tools/lib/api/Makefile
> > +++ b/tools/lib/api/Makefile
> > @@ -99,7 +99,7 @@ install_lib: $(LIBFILE)
> > $(call do_install_mkdir,$(libdir_SQ)); \
> > cp -fpR $(LIBFILE) $(DESTDIR)$(libdir_SQ)
> >
> > -HDRS := cpu.h debug.h io.h
> > +HDRS := cpu.h debug.h io.h io_dir.h
> > FD_HDRS := fd/array.h
> > FS_HDRS := fs/fs.h fs/tracing_path.h
> > INSTALL_HDRS_PFX := $(DESTDIR)$(prefix)/include/api
> > diff --git a/tools/lib/api/io_dir.h b/tools/lib/api/io_dir.h
> > new file mode 100644
> > index 000000000000..9b702497e05c
> > --- /dev/null
> > +++ b/tools/lib/api/io_dir.h
> > @@ -0,0 +1,84 @@
> > +/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
> > +/*
> > + * Lightweight directory reading library.
> > + */
> > +#ifndef __API_IO_DIR__
> > +#define __API_IO_DIR__
> > +
> > +#include <dirent.h>
> > +#include <fcntl.h>
> > +#include <stdlib.h>
> > +#include <unistd.h>
> > +#include <sys/stat.h>
> > +
> > +#ifndef HAVE_GETDENTS64
> > +#include <sys/syscall.h>
> > +
> > +static inline ssize_t getdents64(int fd, void *dirp, size_t count)
> > +{
> > + return syscall(SYS_getdents64, fd, dirp, count);
> > +}
> > +#endif
> > +
> > +struct io_dirent64 {
> > + ino64_t d_ino; /* 64-bit inode number */
> > + off64_t d_off; /* 64-bit offset to next structure */
> > + unsigned short d_reclen; /* Size of this dirent */
> > + unsigned char d_type; /* File type */
> > + char d_name[NAME_MAX + 1]; /* Filename (null-terminated) */
> > +};
> > +
> > +struct io_dir {
> > + int dirfd;
> > + ssize_t available_bytes;
> > + struct io_dirent64 *next;
> > + struct io_dirent64 buff[4];
> > +};
> > +
> > +static inline void io_dir__init(struct io_dir *iod, int dirfd)
> > +{
> > + iod->dirfd = dirfd;
> > + iod->available_bytes = 0;
> > +}
> > +
> > +static inline void io_dir__rewinddir(struct io_dir *iod)
> > +{
> > + lseek(iod->dirfd, 0, SEEK_SET);
> > + iod->available_bytes = 0;
> > +}
> > +
> > +static inline struct io_dirent64 *io_dir__readdir(struct io_dir *iod)
> > +{
> > + struct io_dirent64 *entry;
> > +
> > + if (iod->available_bytes <= 0) {
> > + ssize_t rc = getdents64(iod->dirfd, iod->buff, sizeof(iod->buff));
> > +
> > + if (rc <= 0)
> > + return NULL;
> > + iod->available_bytes = rc;
> > + iod->next = iod->buff;
> > + }
> > + entry = iod->next;
> > + iod->next = (struct io_dirent64 *)((char *)entry + entry->d_reclen);
> > + iod->available_bytes -= entry->d_reclen;
> > + return entry;
> > +}
> > +
> > +static inline bool io_dir__is_dir(const struct io_dir *iod, struct io_dirent64 *dent)
> > +{
> > + if (dent->d_type == DT_UNKNOWN) {
> > + struct stat st;
> > +
> > + if (fstatat(iod->dirfd, dent->d_name, &st, /*flags=*/0))
> > + return false;
> > +
> > + if (S_ISDIR(st.st_mode)) {
> > + dent->d_type = DT_DIR;
> > + return true;
> > + }
> > + }
> > + return dent->d_type == DT_DIR;
> > +}
> > +
> > +#endif
> > diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> > index aa55850fbc21..1cef1ab4ddb7 100644
> > --- a/tools/perf/Makefile.config
> > +++ b/tools/perf/Makefile.config
> > @@ -357,6 +357,10 @@ ifeq ($(feature-stackprotector-all), 1)
> > CORE_CFLAGS += -fstack-protector-all
> > endif
> >
> > +ifeq ($(feature-getdents64), 1)
> > + CFLAGS += -DHAVE_GETDENTS64
> > +endif
> > +
> > ifeq ($(DEBUG),0)
> > ifeq ($(feature-fortify-source), 1)
> > CORE_CFLAGS += -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2
> > --
> > 2.43.0.rc2.451.g8631bc7472-goog
> >
On Mon, Dec 11, 2023 at 3:54 PM Ian Rogers <[email protected]> wrote:
>
> On Mon, Dec 11, 2023 at 3:25 PM Namhyung Kim <[email protected]> wrote:
> >
> > On Wed, Dec 6, 2023 at 9:04 PM Ian Rogers <[email protected]> wrote:
> > >
> > > glibc's opendir allocates a minimum of 32kb, when called recursively
> > > for a directory tree the memory consumption can add up - nearly 300kb
> > > during perf start-up when processing modules. Add a stack allocated
> > > variant of readdir sized a little more than 1kb.
> > >
> > > As getdents64 may be missing from libc, add support using syscall.
> >
> > Unfortunately my alpine build has:
> >
> > In file included from util/machine.c:2:
> > /build/libapi/include/api/io_dir.h:17:23: error: conflicting types for
> > 'getdents'; have 'ssize_t(int, void *, size_t)' {aka 'long int(int,
> > void *, long unsigned int)'}
> > 17 | static inline ssize_t getdents64(int fd, void *dirp, size_t count)
> > | ^~~~~~~~~~
> > /usr/include/dirent.h:52:5: note: previous declaration of 'getdents'
> > with type 'int(int, struct dirent *, size_t)' {aka 'int(int, struct
> > dirent *, long unsigned int)'}
> > 52 | int getdents(int, struct dirent *, size_t);
> > | ^~~~~~~~
>
> Presumably there is a #define getdents64 getdents .. Could we stop
> caring about this version of Alpine linux?
Right, there's a #define:
https://git.musl-libc.org/cgit/musl/tree/include/dirent.h#n68
But I'm not sure ignoring Alpine linux is a good idea.
Maybe we can add a #undef right before?
Thanks,
Namhyung