[PATCH 08/19] selftests/timers: Add threaded time inconsistency test from timetest suite

[John Stultz <john.stultz@linaro.org>]

Add the threaded time inconsistency test from the timetest suite.
This checks for time inconsistencies between cpus, usually associated
with clock skew as sometimes found w/ TSCs.

Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
 tools/testing/selftests/timers/Makefile     |   4 +-
 tools/testing/selftests/timers/threadtest.c | 202 ++++++++++++++++++++++++++++
 2 files changed, 204 insertions(+), 2 deletions(-)
 create mode 100644 tools/testing/selftests/timers/threadtest.c

diff --git a/tools/testing/selftests/timers/Makefile b/tools/testing/selftests/timers/Makefile
index f69bdce..e53b675 100644
--- a/tools/testing/selftests/timers/Makefile
+++ b/tools/testing/selftests/timers/Makefile
@@ -3,7 +3,7 @@ BUILD_FLAGS = -DKTEST
 CFLAGS += -O3 -Wl,-no-as-needed -Wall $(BUILD_FLAGS)
 LDFLAGS += -lrt -lpthread
 bins = posix_timers nanosleep inconsistency-check nsleep-lat raw_skew \
-	set-timer-lat
+	set-timer-lat threadtest
 
 all: ${bins}
 
@@ -14,6 +14,6 @@ run_tests: all
 	./set-timer-lat
 	./inconsistency-check
 	./raw_skew
-
+	./threadtest -t 30 -n 8
 clean:
 	rm -f ${bins}
diff --git a/tools/testing/selftests/timers/threadtest.c b/tools/testing/selftests/timers/threadtest.c
new file mode 100644
index 0000000..6f5fc1c
--- /dev/null
+++ b/tools/testing/selftests/timers/threadtest.c
@@ -0,0 +1,202 @@
+/* threadtest.c
+ *		by: john stultz (johnstul@us.ibm.com)
+ *		(C) Copyright IBM 2004, 2005, 2006, 2012
+ *		Licensed under the GPLv2
+ *
+ *  To build:
+ *	$ gcc threadtest.c -o threadtest -lrt
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ */
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <sys/time.h>
+#include <pthread.h>
+#ifdef KTEST
+#include "../kselftest.h"
+#else
+static inline int ksft_exit_pass(void)
+{
+	exit(0);
+}
+static inline int ksft_exit_fail(void)
+{
+	exit(1);
+}
+#endif
+
+
+/* serializes shared list access */
+pthread_mutex_t list_lock = PTHREAD_MUTEX_INITIALIZER;
+/* serializes console output */
+pthread_mutex_t print_lock = PTHREAD_MUTEX_INITIALIZER;
+
+
+#define MAX_THREADS 128
+#define LISTSIZE 128
+
+extern char *optarg;
+
+int done = 0;
+
+struct timespec global_list[LISTSIZE];
+int listcount = 0;
+
+
+void checklist(struct timespec *list, int size)
+{
+	int i, j;
+	struct timespec *a, *b;
+
+	/* scan the list */
+	for (i = 0; i < size-1; i++) {
+		a = &list[i];
+		b = &list[i+1];
+
+		/* look for any time inconsistencies */
+		if ((b->tv_sec <= a->tv_sec) &&
+			(b->tv_nsec < a->tv_nsec)) {
+
+			/* flag other threads */
+			done = 1;
+
+			/*serialize printing to avoid junky output*/
+			pthread_mutex_lock(&print_lock);
+
+			/* dump the list */
+			printf("\n");
+			for (j = 0; j < size; j++) {
+				if (j == i)
+					printf("---------------\n");
+				printf("%lu:%lu\n", list[j].tv_sec, list[j].tv_nsec);
+				if (j == i+1)
+					printf("---------------\n");
+			}
+			printf("[FAILED]\n");
+
+			pthread_mutex_unlock(&print_lock);
+		}
+	}
+}
+
+/* The shared thread shares a global list
+ * that each thread fills while holding the lock.
+ * This stresses clock syncronization across cpus.
+ */
+void *shared_thread(void *arg)
+{
+	while (!done) {
+		/* protect the list */
+		pthread_mutex_lock(&list_lock);
+
+		/* see if we're ready to check the list */
+		if (listcount >= LISTSIZE) {
+			checklist(global_list, LISTSIZE);
+			listcount = 0;
+		}
+		clock_gettime(CLOCK_MONOTONIC, &global_list[listcount++]);
+
+		pthread_mutex_unlock(&list_lock);
+	}
+	return NULL;
+}
+
+
+/* Each independent thread fills in its own
+ * list. This stresses clock_gettime() lock contention.
+ */
+void *independent_thread(void *arg)
+{
+	struct timespec my_list[LISTSIZE];
+	int count;
+
+	while (!done) {
+		/* fill the list */
+		for (count = 0; count < LISTSIZE; count++)
+			clock_gettime(CLOCK_MONOTONIC, &my_list[count]);
+		checklist(my_list, LISTSIZE);
+	}
+	return NULL;
+}
+
+
+int main(int argc, char **argv)
+{
+	int thread_count = 1, i;
+	time_t start, now, runtime = 60;
+	char buf[255];
+	pthread_t pth[MAX_THREADS];
+	int opt;
+	void *tret;
+	int ret = 0;
+	void *(*thread)(void *) = shared_thread;
+
+
+	/* Process arguments */
+	while ((opt = getopt(argc, argv, "t:n:i")) != -1) {
+		switch (opt) {
+		case 't':
+			runtime = atoi(optarg);
+			break;
+		case 'n':
+			thread_count = atoi(optarg);
+			break;
+		case 'i':
+			thread = independent_thread;
+			printf("using independent threads\n");
+			break;
+		default:
+			printf("Usage: %s [-t <secs>] [-n <numthreads>] [-i]\n", argv[0]);
+			printf("	-t: time to run\n");
+			printf("	-n: number of threads\n");
+			printf("	-i: use independent threads\n");
+			return -1;
+		}
+	}
+
+	if (thread_count > MAX_THREADS)
+		thread_count = MAX_THREADS;
+
+
+	setbuf(stdout, NULL);
+
+	start = time(0);
+	strftime(buf, 255, "%a, %d %b %Y %T %z", localtime(&start));
+	printf("%s\n", buf);
+	printf("Testing consistency with %i threads for %ld seconds: ", thread_count, runtime);
+
+	/* spawn */
+	for (i = 0; i < thread_count; i++)
+		pthread_create(&pth[i], 0, thread, 0);
+
+	while (time(&now) < start + runtime) {
+		sleep(1);
+		if (done) {
+			ret = 1;
+			strftime(buf, 255, "%a, %d %b %Y %T %z", localtime(&now));
+			printf("%s\n", buf);
+			goto out;
+		}
+	}
+	printf("[OK]\n");
+	done = 1;
+
+out:
+	/* wait */
+	for (i = 0; i < thread_count; i++)
+		pthread_join(pth[i], &tret);
+
+	/* die */
+	if (ret)
+		ksft_exit_fail();
+	return ksft_exit_pass();
+}
-- 
1.9.1