linux-kernel - [PATCH v3 2/8] perf maps: Switch modules tree walk to io_dir_

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Message-Id: <20250222061015.303622-3-irogers@google.com>
Date: Fri, 21 Feb 2025 22:10:07 -0800
From: Ian Rogers <irogers@...gle.com>
To: Namhyung Kim <namhyung@...nel.org>, 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>, 
	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>, 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>
Cc: Ian Rogers <irogers@...gle.com>
Subject: [PATCH v3 2/8] 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.

Acked-by: Namhyung Kim <namhyung@...nel.org>
Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/machine.c | 25 ++++++++-----------------
 1 file changed, 8 insertions(+), 17 deletions(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 316f0879e5e0..e394c630e3a2 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -37,6 +37,7 @@
 #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>
@@ -1339,31 +1340,21 @@ 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)
 {
-	const 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];
-		unsigned char d_type = dent->d_type;
 
 		path__join(path, sizeof(path), dir_name, dent->d_name);
-
-		if (d_type == DT_UNKNOWN) {
-			struct stat st;
-
-			if (stat(path, &st))
-				continue;
-			if (S_ISDIR(st.st_mode))
-				d_type = DT_DIR;
-		}
-
-		if (d_type == DT_DIR) {
+		if (io_dir__is_dir(&iod, dent)) {
 			if (!strcmp(dent->d_name, ".") ||
 			    !strcmp(dent->d_name, ".."))
 				continue;
@@ -1396,7 +1387,7 @@ static int maps__set_modules_path_dir(struct maps *maps, const char *dir_name, i
 	}
 
 out:
-	closedir(dir);
+	close(iod.dirfd);
 	return ret;
 }
 
-- 
2.48.1.658.g4767266eb4-goog