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Subject[tip: timers/core] selftests/timens: Add a simple perf test for clock_gettime()
The following commit has been merged into the timers/core branch of tip:

Commit-ID: 1854b97e4fa6a476d5cdc3dc30c42e1528699f87
Gitweb: https://git.kernel.org/tip/1854b97e4fa6a476d5cdc3dc30c42e1528699f87
Author: Andrei Vagin <avagin@gmail.com>
AuthorDate: Tue, 12 Nov 2019 01:27:22
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Tue, 14 Jan 2020 12:21:02 +01:00

selftests/timens: Add a simple perf test for clock_gettime()

Output on success:
1..4
ok 1 host: clock: monotonic cycles: 148323947
ok 2 host: clock: boottime cycles: 148577503
ok 3 ns: clock: monotonic cycles: 137659217
ok 4 ns: clock: boottime cycles: 137959154
# Pass 4 Fail 0 Xfail 0 Xpass 0 Skip 0 Error 0

Output with lack of permissions:
1..4
ok 1 host: clock: monotonic cycles: 145671139
ok 2 host: clock: boottime cycles: 146958357
not ok 3 # SKIP need to run as root

Output without support of time namespaces:
1..4
ok 1 host: clock: monotonic cycles: 145671139
ok 2 host: clock: boottime cycles: 146958357
not ok 3 # SKIP Time namespaces are not supported

Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20191112012724.250792-34-dima@arista.com


---
tools/testing/selftests/timens/.gitignore | 2 +-
tools/testing/selftests/timens/Makefile | 3 +-
tools/testing/selftests/timens/gettime_perf.c | 95 ++++++++++++++++++-
3 files changed, 99 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/timens/gettime_perf.c

diff --git a/tools/testing/selftests/timens/.gitignore b/tools/testing/selftests/timens/.gitignore
index 3b7eda8..16292e4 100644
--- a/tools/testing/selftests/timens/.gitignore
+++ b/tools/testing/selftests/timens/.gitignore
@@ -1,4 +1,6 @@
clock_nanosleep
+gettime_perf
+gettime_perf_cold
procfs
timens
timer
diff --git a/tools/testing/selftests/timens/Makefile b/tools/testing/selftests/timens/Makefile
index 0816454..6aefcac 100644
--- a/tools/testing/selftests/timens/Makefile
+++ b/tools/testing/selftests/timens/Makefile
@@ -1,6 +1,7 @@
TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs
+TEST_GEN_PROGS_EXTENDED := gettime_perf

CFLAGS := -Wall -Werror -pthread
-LDFLAGS := -lrt
+LDFLAGS := -lrt -ldl

include ../lib.mk
diff --git a/tools/testing/selftests/timens/gettime_perf.c b/tools/testing/selftests/timens/gettime_perf.c
new file mode 100644
index 0000000..7bf841a
--- /dev/null
+++ b/tools/testing/selftests/timens/gettime_perf.c
@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <sched.h>
+#include <time.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <dlfcn.h>
+
+#include "log.h"
+#include "timens.h"
+
+typedef int (*vgettime_t)(clockid_t, struct timespec *);
+
+vgettime_t vdso_clock_gettime;
+
+static void fill_function_pointers(void)
+{
+ void *vdso = dlopen("linux-vdso.so.1",
+ RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
+ if (!vdso)
+ vdso = dlopen("linux-gate.so.1",
+ RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
+ if (!vdso) {
+ pr_err("[WARN]\tfailed to find vDSO\n");
+ return;
+ }
+
+ vdso_clock_gettime = (vgettime_t)dlsym(vdso, "__vdso_clock_gettime");
+ if (!vdso_clock_gettime)
+ pr_err("Warning: failed to find clock_gettime in vDSO\n");
+
+}
+
+static void test(clock_t clockid, char *clockstr, bool in_ns)
+{
+ struct timespec tp, start;
+ long i = 0;
+ const int timeout = 3;
+
+ vdso_clock_gettime(clockid, &start);
+ tp = start;
+ for (tp = start; start.tv_sec + timeout > tp.tv_sec ||
+ (start.tv_sec + timeout == tp.tv_sec &&
+ start.tv_nsec > tp.tv_nsec); i++) {
+ vdso_clock_gettime(clockid, &tp);
+ }
+
+ ksft_test_result_pass("%s:\tclock: %10s\tcycles:\t%10ld\n",
+ in_ns ? "ns" : "host", clockstr, i);
+}
+
+int main(int argc, char *argv[])
+{
+ time_t offset = 10;
+ int nsfd;
+
+ ksft_set_plan(8);
+
+ fill_function_pointers();
+
+ test(CLOCK_MONOTONIC, "monotonic", false);
+ test(CLOCK_MONOTONIC_COARSE, "monotonic-coarse", false);
+ test(CLOCK_MONOTONIC_RAW, "monotonic-raw", false);
+ test(CLOCK_BOOTTIME, "boottime", false);
+
+ nscheck();
+
+ if (unshare_timens())
+ return 1;
+
+ nsfd = open("/proc/self/ns/time_for_children", O_RDONLY);
+ if (nsfd < 0)
+ return pr_perror("Can't open a time namespace");
+
+ if (_settime(CLOCK_MONOTONIC, offset))
+ return 1;
+ if (_settime(CLOCK_BOOTTIME, offset))
+ return 1;
+
+ if (setns(nsfd, CLONE_NEWTIME))
+ return pr_perror("setns");
+
+ test(CLOCK_MONOTONIC, "monotonic", true);
+ test(CLOCK_MONOTONIC_COARSE, "monotonic-coarse", true);
+ test(CLOCK_MONOTONIC_RAW, "monotonic-raw", true);
+ test(CLOCK_BOOTTIME, "boottime", true);
+
+ ksft_exit_pass();
+ return 0;
+}
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