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Date: Fri, 15 Mar 2013 17:54:02 +0100
From: Frederic Weisbecker <fweisbec@...il.com>
To: Thomas Gleixner <tglx@...utronix.de>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
Frederic Weisbecker <fweisbec@...il.com>,
Stanislaw Gruszka <sgruszka@...hat.com>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Steven Rostedt <rostedt@...dmis.org>
Subject: [PATCH 4/4] selftests: Add basic posix timers selftests
Add some initial basic tests on a few posix timers
interface such as setitimer() and timer_settime().
These simply check that expiration happens in a reasonable
timeframe after expected elapsed clock time (user time,
user + system time, real time, ...).
This is helpful for finding basic breakages while hacking
on this subsystem.
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
Cc: Stanislaw Gruszka <sgruszka@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
---
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/timers/Makefile | 8 +
tools/testing/selftests/timers/posix_timers.c | 221 +++++++++++++++++++++++++
3 files changed, 230 insertions(+), 0 deletions(-)
create mode 100644 tools/testing/selftests/timers/Makefile
create mode 100644 tools/testing/selftests/timers/posix_timers.c
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 3cc0ad7..4bdaede 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -5,6 +5,7 @@ TARGETS += vm
TARGETS += cpu-hotplug
TARGETS += memory-hotplug
TARGETS += efivarfs
+TARGETS += timers
all:
for TARGET in $(TARGETS); do \
diff --git a/tools/testing/selftests/timers/Makefile b/tools/testing/selftests/timers/Makefile
new file mode 100644
index 0000000..eb2859f
--- /dev/null
+++ b/tools/testing/selftests/timers/Makefile
@@ -0,0 +1,8 @@
+all:
+ gcc posix_timers.c -o posix_timers -lrt
+
+run_tests: all
+ ./posix_timers
+
+clean:
+ rm -f ./posix_timers
diff --git a/tools/testing/selftests/timers/posix_timers.c b/tools/testing/selftests/timers/posix_timers.c
new file mode 100644
index 0000000..4fa655d
--- /dev/null
+++ b/tools/testing/selftests/timers/posix_timers.c
@@ -0,0 +1,221 @@
+/*
+ * Copyright (C) 2013 Red Hat, Inc., Frederic Weisbecker <fweisbec@...hat.com>
+ *
+ * Licensed under the terms of the GNU GPL License version 2
+ *
+ * Selftests for a few posix timers interface.
+ *
+ * Kernel loop code stolen from Steven Rostedt <srostedt@...hat.com>
+ */
+
+#include <sys/time.h>
+#include <stdio.h>
+#include <signal.h>
+#include <unistd.h>
+#include <time.h>
+#include <pthread.h>
+
+#define DELAY 2
+#define USECS_PER_SEC 1000000
+
+static volatile int done;
+
+/* Busy loop in userspace to elapse ITIMER_VIRTUAL */
+static void user_loop(void)
+{
+ while (!done);
+}
+
+/*
+ * Try to spend as much time as possible in kernelspace
+ * to elapse ITIMER_PROF.
+ */
+static void kernel_loop(void)
+{
+ void *addr = sbrk(0);
+
+ while (!done) {
+ brk(addr + 4096);
+ brk(addr);
+ }
+}
+
+/*
+ * Sleep until ITIMER_REAL expiration.
+ */
+static void idle_loop(void)
+{
+ pause();
+}
+
+static void sig_handler(int nr)
+{
+ done = 1;
+}
+
+/*
+ * Check the expected timer expiration matches the GTOD elapsed delta since
+ * we armed the timer. Keep a 0.5 sec error margin due to various jitter.
+ */
+static int check_diff(struct timeval start, struct timeval end)
+{
+ long long diff;
+
+ diff = end.tv_usec - start.tv_usec;
+ diff += (end.tv_sec - start.tv_sec) * USECS_PER_SEC;
+
+ if (abs(diff - DELAY * USECS_PER_SEC) > USECS_PER_SEC / 2) {
+ printf("Diff too high: %lld..", diff);
+ return -1;
+ }
+
+ return 0;
+}
+
+static int check_itimer(int which)
+{
+ int err;
+ struct timeval start, end;
+ struct itimerval val = {
+ .it_value.tv_sec = DELAY,
+ };
+
+ printf("Check itimer ");
+
+ if (which == ITIMER_VIRTUAL)
+ printf("virtual... ");
+ else if (which == ITIMER_PROF)
+ printf("prof... ");
+ else if (which == ITIMER_REAL)
+ printf("real... ");
+
+ fflush(stdout);
+
+ done = 0;
+
+ if (which == ITIMER_VIRTUAL)
+ signal(SIGVTALRM, sig_handler);
+ else if (which == ITIMER_PROF)
+ signal(SIGPROF, sig_handler);
+ else if (which == ITIMER_REAL)
+ signal(SIGALRM, sig_handler);
+
+ err = gettimeofday(&start, NULL);
+ if (err < 0) {
+ perror("Can't call gettimeofday()\n");
+ return -1;
+ }
+
+ err = setitimer(which, &val, NULL);
+ if (err < 0) {
+ perror("Can't set timer\n");
+ return -1;
+ }
+
+ if (which == ITIMER_VIRTUAL)
+ user_loop();
+ else if (which == ITIMER_PROF)
+ kernel_loop();
+ else if (which == ITIMER_REAL)
+ idle_loop();
+
+ gettimeofday(&end, NULL);
+ if (err < 0) {
+ perror("Can't call gettimeofday()\n");
+ return -1;
+ }
+
+ if (!check_diff(start, end))
+ printf("[OK]\n");
+ else
+ printf("[FAIL]\n");
+
+ return 0;
+}
+
+static int check_timer_create(int which)
+{
+ int err;
+ timer_t id;
+ struct timeval start, end;
+ struct itimerspec val = {
+ .it_value.tv_sec = DELAY,
+ };
+
+ printf("Check timer_create() ");
+ if (which == CLOCK_THREAD_CPUTIME_ID) {
+ printf("per thread... ");
+ } else if (which == CLOCK_PROCESS_CPUTIME_ID) {
+ printf("per process... ");
+ }
+ fflush(stdout);
+
+ done = 0;
+ timer_create(which, NULL, &id);
+ if (err < 0) {
+ perror("Can't create timer\n");
+ return -1;
+ }
+ signal(SIGALRM, sig_handler);
+
+ err = gettimeofday(&start, NULL);
+ if (err < 0) {
+ perror("Can't call gettimeofday()\n");
+ return -1;
+ }
+
+ err = timer_settime(id, 0, &val, NULL);
+ if (err < 0) {
+ perror("Can't set timer\n");
+ return -1;
+ }
+
+ user_loop();
+
+ gettimeofday(&end, NULL);
+ if (err < 0) {
+ perror("Can't call gettimeofday()\n");
+ return -1;
+ }
+
+ if (!check_diff(start, end))
+ printf("[OK]\n");
+ else
+ printf("[FAIL]\n");
+
+ return 0;
+}
+
+int main(int argc, char **argv)
+{
+ int err;
+
+ printf("Testing posix timers. False negative may happen on CPU execution \n");
+ printf("based timers if other threads run on the CPU...\n");
+
+ if (check_itimer(ITIMER_VIRTUAL) < 0)
+ return -1;
+
+ if (check_itimer(ITIMER_PROF) < 0)
+ return -1;
+
+ if (check_itimer(ITIMER_REAL) < 0)
+ return -1;
+
+ if (check_timer_create(CLOCK_THREAD_CPUTIME_ID) < 0)
+ return -1;
+
+ /*
+ * It's unfortunately hard to reliably test a timer expiration
+ * on parallel multithread cputime. We could arm it to expire
+ * on DELAY * nr_threads, with nr_threads busy looping, then wait
+ * the normal DELAY since the time is elapsing nr_threads faster.
+ * But for that we need to ensure we have real physical free CPUs
+ * to ensure true parallelism. So test only one thread until we
+ * find a better solution.
+ */
+ if (check_timer_create(CLOCK_PROCESS_CPUTIME_ID) < 0)
+ return -1;
+
+ return 0;
+}
--
1.7.5.4
--
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