[PATCHv5 36/37] selftests/timens: Add a simple perf test for clock_gettime()
Dmitry Safonov
dima at arista.com
Mon Jul 29 21:57:18 UTC 2019
From: Andrei Vagin <avagin at gmail.com>
Signed-off-by: Andrei Vagin <avagin at gmail.com>
Co-developed-by: Dmitry Safonov <dima at arista.com>
Signed-off-by: Dmitry Safonov <dima at arista.com>
---
tools/testing/selftests/timens/.gitignore | 2 +
tools/testing/selftests/timens/Makefile | 10 +-
tools/testing/selftests/timens/gettime_perf.c | 101 +++++++++++
.../selftests/timens/gettime_perf_cold.c | 160 ++++++++++++++++++
4 files changed, 271 insertions(+), 2 deletions(-)
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..97e0460eaf48 100644
--- a/tools/testing/selftests/timens/Makefile
+++ b/tools/testing/selftests/timens/Makefile
@@ -1,6 +1,12 @@
-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
+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 000000000000..f7d7832c0293
--- /dev/null
+++ b/tools/testing/selftests/timens/gettime_perf.c
@@ -0,0 +1,101 @@
+// 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"
+
+//#define TEST_SYSCALL
+
+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;
+
+#ifndef TEST_SYSCALL
+ vdso_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
+ vdso_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;
+
+ ksft_set_plan(4);
+
+ fill_function_pointers();
+
+ 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..2ab0869744a6
--- /dev/null
+++ b/tools/testing/selftests/timens/gettime_perf_cold.c
@@ -0,0 +1,160 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <sys/types.h>
+#include <sys/mman.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 <dlfcn.h>
+#include <signal.h>
+
+#include "log.h"
+#include "timens.h"
+
+#define PAGE_SIZE 4096
+#define CACHE_LINE_SIZE 64
+
+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 inline __attribute__((always_inline)) unsigned long long rdtsc(void)
+{
+ unsigned int hi, lo;
+
+ __asm__ __volatile__ ("rdtsc" : "=a"(lo), "=d"(hi));
+ return ((unsigned long long) lo) | (((unsigned long long)hi) << 32);
+}
+
+static inline __attribute__((always_inline)) void test(clock_t clockid, char *clockstr)
+{
+ struct timespec tp;
+ long long s, e;
+
+ s = rdtsc();
+ vdso_clock_gettime(clockid, &tp);
+ e = rdtsc();
+ printf("%lld\n", e - s);
+}
+
+static inline void clflush(volatile void *__p)
+{
+ asm volatile("clflush %0" : "+m"(*(volatile char *)__p));
+}
+
+void *pg_addr;
+void sigh(int sig)
+{
+ void *addr;
+
+ addr = mmap(pg_addr, PAGE_SIZE, PROT_READ,
+ MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
+ if (addr != pg_addr) {
+ pr_perror("Unable to map %lx", (long) pg_addr);
+ exit(1);
+ }
+}
+
+int main(int argc, char **argv)
+{
+ time_t offset = 10;
+ void *vdso_start = 0, *vdso_end = 0;
+ void *vvar_start = 0, *vvar_end = 0;
+ char buf[PAGE_SIZE];
+ int nsfd, i;
+ FILE *maps;
+
+ fill_function_pointers();
+ if (argc == 1)
+ goto out;
+ 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");
+
+out:
+ maps = fopen("/proc/self/maps", "r");
+ if (!maps) {
+ pr_perror("Unable to open /proc/self/maps");
+ return 1;
+ }
+
+ while (fgets(buf, sizeof(buf), maps)) {
+ unsigned long start, end;
+ char tail[PAGE_SIZE];
+ int r;
+
+ r = sscanf(buf, "%lx-%lx %*s %*s %*s %*s %s\n", &start, &end, tail);
+
+ if (r < 3)
+ continue;
+
+ if (strcmp(tail, "[vdso]") == 0) {
+ vdso_start = (void *)start;
+ vdso_end = (void *)end;
+ }
+ if (strcmp(tail, "[vvar]") == 0) {
+ vvar_start = (void *)start;
+ vvar_end = (void *)end;
+ }
+ }
+ if (!vvar_start || !vdso_start) {
+ pr_err("Unable to find vdso\n");
+ return 1;
+ }
+
+ /* Map zero pages instead of unreadable vdso pages. */
+ signal(SIGSEGV, sigh);
+ signal(SIGBUS, sigh);
+ for (pg_addr = vdso_start; pg_addr < vdso_end; pg_addr += PAGE_SIZE)
+ buf[0] += *(char *)pg_addr;
+ for (pg_addr = vvar_start; pg_addr < vvar_end; pg_addr += PAGE_SIZE)
+ buf[0] += *(char *)pg_addr;
+ signal(SIGSEGV, SIG_DFL);
+ signal(SIGBUS, SIG_DFL);
+
+ for (i = 0; i < 10240; i++) {
+ void *p;
+
+ for (p = vdso_start; p < vdso_end; p += CACHE_LINE_SIZE)
+ clflush(p);
+ for (p = vvar_start; p < vvar_end; p += CACHE_LINE_SIZE)
+ clflush(p);
+ test(CLOCK_MONOTONIC, "monotonic");
+ }
+ return 0;
+}
--
2.22.0
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