This tool fills dcache with negative dentries. Between iterations it prints
statistics and measures time of inotify operation which might degrade.
Signed-off-by: Konstantin Khlebnikov
---
tools/testing/selftests/filesystems/Makefile |1
.../testing/selftests/filesystems/dcache_stress.c | 210
2 files changed, 211 insertions(+)
create mode 100644 tools/testing/selftests/filesystems/dcache_stress.c
diff --git a/tools/testing/selftests/filesystems/Makefile
b/tools/testing/selftests/filesystems/Makefile
index 129880fb42d3..6b5e08617d11 100644
--- a/tools/testing/selftests/filesystems/Makefile
+++ b/tools/testing/selftests/filesystems/Makefile
@@ -3,5 +3,6 @@
CFLAGS += -I../../../../usr/include/
TEST_GEN_PROGS := devpts_pts
TEST_GEN_PROGS_EXTENDED := dnotify_test
+TEST_GEN_FILES += dcache_stress
include ../lib.mk
diff --git a/tools/testing/selftests/filesystems/dcache_stress.c
b/tools/testing/selftests/filesystems/dcache_stress.c
new file mode 100644
index ..770e8876629e
--- /dev/null
+++ b/tools/testing/selftests/filesystems/dcache_stress.c
@@ -0,0 +1,210 @@
+// SPDX-License-Identifier: GPL-2.0
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+
+double now(void)
+{
+ struct timespec ts;
+
+ clock_gettime(CLOCK_MONOTONIC, );
+ return ts.tv_sec + ts.tv_nsec * 1e-9;
+}
+
+struct dentry_stat {
+ long nr_dentry;
+ long nr_unused;
+ long age_limit; /* age in seconds */
+ long want_pages;/* pages requested by system */
+ long nr_negative; /* # of unused negative dentries */
+ long nr_buckets;/* count of dcache hash buckets */
+};
+
+void show_dentry_state(void)
+{
+ struct dentry_stat stat;
+ ssize_t len;
+ FILE *f;
+
+ f = fopen("/proc/sys/fs/dentry-state", "r");
+ if (!f)
+ err(2, "open fs.dentry-state");
+
+ if (fscanf(f, "%ld %ld %ld %ld %ld %ld",
+ _dentry,
+ _unused,
+ _limit,
+ _pages,
+ _negative,
+ _buckets) != 6)
+ err(2, "read fs.dentry-state");
+ fclose(f);
+
+ if (!stat.nr_buckets)
+ stat.nr_buckets = 1 << 20; // for 8Gb ram
+
+ printf("nr_dentry = %ld\t%.1fM\n", stat.nr_dentry, stat.nr_dentry /
1e6);
+ printf("nr_buckets = %ld\t%.1f avg\n", stat.nr_buckets,
(double)stat.nr_dentry / stat.nr_buckets);
+ printf("nr_unused = %ld\t%.1f%%\n", stat.nr_unused, stat.nr_unused *
100. / stat.nr_dentry);
+ printf("nr_negative = %ld\t%.1f%%\n\n", stat.nr_negative,
stat.nr_negative * 100. / stat.nr_dentry);
+}
+
+void test_inotify(const char *path)
+{
+ double tm;
+ int fd;
+
+ fd = inotify_init1(0);
+
+ tm = now();
+ inotify_add_watch(fd, path, IN_OPEN);
+ tm = now() - tm;
+
+ printf("inotify time: %f seconds\n\n", tm);
+
+ close(fd);
+}
+
+int main(int argc, char **argv)
+{
+ char dir_name[] = "dcache_stress.XX";
+ char name[4096];
+ char *suffix = name;
+ int nr_iterations = 10;
+ int nr_names = 1 << 20;
+ int iteration, index;
+ int other_dir = -1;
+ int mknod_unlink = 0;
+ int mkdir_chdir = 0;
+ int second_access = 0;
+ long long total_names = 0;
+ double tm;
+ int opt;
+
+ while ((opt = getopt(argc, argv, "i:n:p:o:usdh")) != -1) {
+ switch (opt) {
+ case 'i':
+ nr_iterations = atoi(optarg);
+ break;
+ case 'n':
+ nr_names = atoi(optarg);
+ break;
+ case 'p':
+ strcpy(suffix, optarg);
+ suffix += strlen(suffix);
+ break;
+ case 'o':
+ other_dir = open(optarg, O_RDONLY | O_DIRECTORY);
+ if (other_dir < 0)
+ err(2, "open %s", optarg);
+ break;
+ case 'u':
+ mknod_unlink = 1;
+ break;
+ case 'd':
+ mkdir_chdir = 1;
+ break;
+ case 's':
+ second_access = 1;
+ break;
+ case '?':
+ case 'h':
+ printf("usage: %s [-i ] [-n ] [-p
] [-o ] [-u] [-s]\n"
+ " -i test iterations, default %d\n"
+ " -n names at each iterations, default %d\n"
+ " -p prefix for names\n"
+ " -o interlave with other dir\n"
+ " -s touch twice\n"
+ " -u mknod-unlink
