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Date:   Thu,  2 Nov 2023 10:56:55 -0700
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Subject: [PATCH v4 13/53] perf header: Switch mem topology to io_dir__readdir
From:   Ian Rogers <irogers@google.com>
To:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Ian Rogers <irogers@google.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Nick Terrell <terrelln@fb.com>,
        Kan Liang <kan.liang@linux.intel.com>,
        Andi Kleen <ak@linux.intel.com>,
        Kajol Jain <kjain@linux.ibm.com>,
        Athira Rajeev <atrajeev@linux.vnet.ibm.com>,
        Huacai Chen <chenhuacai@kernel.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Vincent Whitchurch <vincent.whitchurch@axis.com>,
        "Steinar H. Gunderson" <sesse@google.com>,
        Liam Howlett <liam.howlett@oracle.com>,
        Miguel Ojeda <ojeda@kernel.org>,
        Colin Ian King <colin.i.king@gmail.com>,
        Dmitrii Dolgov <9erthalion6@gmail.com>,
        Yang Jihong <yangjihong1@huawei.com>,
        Ming Wang <wangming01@loongson.cn>,
        James Clark <james.clark@arm.com>,
        K Prateek Nayak <kprateek.nayak@amd.com>,
        Sean Christopherson <seanjc@google.com>,
        Leo Yan <leo.yan@linaro.org>,
        Ravi Bangoria <ravi.bangoria@amd.com>,
        German Gomez <german.gomez@arm.com>,
        Changbin Du <changbin.du@huawei.com>,
        Paolo Bonzini <pbonzini@redhat.com>, Li Dong <lidong@vivo.com>,
        Sandipan Das <sandipan.das@amd.com>,
        liuwenyu <liuwenyu7@huawei.com>, linux-kernel@vger.kernel.org,
        linux-perf-users@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

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@google.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 e86b9439ffee..55f63d2ee232 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;
 
@@ -1447,7 +1448,7 @@ static int build_mem_topology(struct memory_node **nodesp, u64 *cntp)
 		ret = memory_node__read(&nodes[cnt++], idx);
 	}
 out:
-	closedir(dir);
+	close(dir.dirfd);
 	if (!ret) {
 		*cntp = cnt;
 		*nodesp = nodes;
-- 
2.42.0.869.gea05f2083d-goog