linux-kernel - [PATCH v2 4/7] perf header: Switch mem topology to io_dir_

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Message-Id: <20250207232452.994822-5-irogers@google.com>
Date: Fri,  7 Feb 2025 15:24:45 -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 4/7] perf header: Switch mem topology to io_dir__readdir

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 <irogers@...gle.com>
---
 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 d06aa86352d3..1900965f8752 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"
@@ -1311,11 +1312,11 @@ 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)
@@ -1324,9 +1325,9 @@ 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;
 	}
 
@@ -1338,20 +1339,20 @@ 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;
 }
 
@@ -1374,8 +1375,8 @@ 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;
@@ -1383,14 +1384,14 @@ 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;
 
@@ -1419,7 +1420,7 @@ 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;
-- 
2.48.1.502.g6dc24dfdaf-goog