[PATCHv3 26/27] selftests: Add a simple perf test for clock_gettime()

[Dmitry Safonov <dima@arista.com>]

From: Andrei Vagin <avagin@gmail.com>

Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 tools/testing/selftests/timens/.gitignore     |  2 +
 tools/testing/selftests/timens/Makefile       |  8 +-
 tools/testing/selftests/timens/gettime_perf.c | 74 +++++++++++++++++++
 .../selftests/timens/gettime_perf_cold.c      | 63 ++++++++++++++++
 4 files changed, 146 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/timens/gettime_perf.c
 create mode 100644 tools/testing/selftests/timens/gettime_perf_cold.c

diff --git a/tools/testing/selftests/timens/.gitignore b/tools/testing/selftests/timens/.gitignore
index 3b7eda8f35ce..16292e4d08a5 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 ae1ffd24cc43..ef65bf96b55c 100644
--- a/tools/testing/selftests/timens/Makefile
+++ b/tools/testing/selftests/timens/Makefile
@@ -1,4 +1,10 @@
-TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs
+TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs gettime_perf
+
+uname_M := $(shell uname -m 2>/dev/null || echo not)
+ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/i386/)
+ifeq ($(ARCH),x86_64)
+TEST_GEN_PROGS += gettime_perf_cold
+endif
 
 CFLAGS := -Wall -Werror
 LDFLAGS := -lrt
diff --git a/tools/testing/selftests/timens/gettime_perf.c b/tools/testing/selftests/timens/gettime_perf.c
new file mode 100644
index 000000000000..510d77a941d9
--- /dev/null
+++ b/tools/testing/selftests/timens/gettime_perf.c
@@ -0,0 +1,74 @@
+// 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 "log.h"
+#include "timens.h"
+
+//#define TEST_SYSCALL
+
+static void test(clock_t clockid, char *clockstr, bool in_ns)
+{
+	struct timespec tp, start;
+	long i = 0;
+	const int timeout = 3;
+
+#ifndef TEST_SYSCALL
+	clock_gettime(clockid, &start);
+#else
+	syscall(__NR_clock_gettime, clockid, &start);
+#endif
+	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++) {
+#ifndef TEST_SYSCALL
+		clock_gettime(clockid, &tp);
+#else
+		syscall(__NR_clock_gettime, clockid, &tp);
+#endif
+	}
+
+	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;
+
+	test(CLOCK_MONOTONIC, "monotonic", false);
+	test(CLOCK_BOOTTIME, "boottime", false);
+
+	nscheck();
+
+	if (unshare(CLONE_NEWTIME))
+		return pr_perror("Can't unshare() timens");
+
+	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_BOOTTIME, "boottime", true);
+
+	ksft_exit_pass();
+	return 0;
+}
diff --git a/tools/testing/selftests/timens/gettime_perf_cold.c b/tools/testing/selftests/timens/gettime_perf_cold.c
new file mode 100644
index 000000000000..f72db8a4c903
--- /dev/null
+++ b/tools/testing/selftests/timens/gettime_perf_cold.c
@@ -0,0 +1,63 @@
+// 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 <string.h>
+
+#include "log.h"
+#include "timens.h"
+
+static __inline__ unsigned long long rdtsc(void)
+{
+	unsigned hi, lo;
+
+	__asm__ __volatile__ ("rdtsc" : "=a"(lo), "=d"(hi));
+	return ((unsigned long long) lo) | (((unsigned long long)hi) << 32);
+}
+
+static void test(clock_t clockid, char *clockstr)
+{
+	struct timespec tp;
+	long long s, e;
+
+	s = rdtsc();
+	clock_gettime(clockid, &tp);
+	e = rdtsc();
+	printf("%lld\n", e - s);
+	return;
+}
+
+int main(int argc, char **argv)
+{
+	time_t offset = 10;
+	int nsfd;
+
+	if (argc == 1) {
+		test(CLOCK_MONOTONIC, "monotonic");
+		return 0;
+	}
+	nscheck();
+
+	if (unshare(CLONE_NEWTIME))
+		return pr_perror("Can't unshare() timens");
+
+	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 (setns(nsfd, CLONE_NEWTIME))
+		return pr_perror("setns");
+
+	test(CLOCK_MONOTONIC, "monotonic");
+	return 0;
+}
-- 
2.21.0