linux-kernel - [PATCH v1 3/6] perf maps: Switch modules tree walk to io_dir_

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Message-Id: <20231207050433.1426834-4-irogers@google.com>
Date:   Wed,  6 Dec 2023 21:04:30 -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>,
        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>,
        "Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
        Thomas Richter <tmricht@...ux.ibm.com>,
        Quentin Monnet <quentin@...valent.com>,
        Fangrui Song <maskray@...gle.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Yanteng Si <siyanteng@...ngson.cn>,
        K Prateek Nayak <kprateek.nayak@....com>,
        Artem Savkov <asavkov@...hat.com>,
        James Clark <james.clark@....com>,
        Ravi Bangoria <ravi.bangoria@....com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Subject: [PATCH v1 3/6] perf maps: Switch modules tree walk to io_dir__readdir

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 <irogers@...gle.com>
---
 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