@@ -278,6 +278,162 @@ static void test_multi_co_mutex_2_30(void)
test_multi_co_mutex(2, 30);
}
+/* Same test with fair mutexes, for performance comparison. */
+
+#ifdef CONFIG_LINUX
+#include "qemu/futex.h"
+
+/* The nodes for the mutex reside in this structure (on which we try to avoid
+ * false sharing). The head of the mutex is in the "mutex_head" variable.
+ */
+static struct {
+ int next, locked;
+ int padding[14];
+} nodes[NUM_CONTEXTS] __attribute__((__aligned__(64)));
+
+static int mutex_head = -1;
+
+static void mcs_mutex_lock(void)
+{
+ int prev;
+
+ nodes[id].next = -1;
+ nodes[id].locked = 1;
+ prev = atomic_xchg(&mutex_head, id);
+ if (prev != -1) {
+ atomic_set(&nodes[prev].next, id);
+ qemu_futex_wait(&nodes[id].locked, 1);
+ }
+}
+
+static void mcs_mutex_unlock(void)
+{
+ int next;
+ if (nodes[id].next == -1) {
+ if (atomic_read(&mutex_head) == id &&
+ atomic_cmpxchg(&mutex_head, id, -1) == id) {
+ /* Last item in the list, exit. */
+ return;
+ }
+ while (atomic_read(&nodes[id].next) == -1) {
+ /* mcs_mutex_lock did the xchg, but has not updated
+ * nodes[prev].next yet.
+ */
+ }
+ }
+
+ /* Wake up the next in line. */
+ next = nodes[id].next;
+ nodes[next].locked = 0;
+ qemu_futex_wake(&nodes[next].locked, 1);
+}
+
+static void test_multi_fair_mutex_entry(void *opaque)
+{
+ while (!atomic_mb_read(&now_stopping)) {
+ mcs_mutex_lock();
+ counter++;
+ mcs_mutex_unlock();
+ atomic_inc(&atomic_counter);
+ }
+ atomic_dec(&running);
+}
+
+static void test_multi_fair_mutex(int threads, int seconds)
+{
+ int i;
+
+ assert(mutex_head == -1);
+ counter = 0;
+ atomic_counter = 0;
+ now_stopping = false;
+
+ create_aio_contexts();
+ assert(threads <= NUM_CONTEXTS);
+ running = threads;
+ for (i = 0; i < threads; i++) {
+ Coroutine *co1 = qemu_coroutine_create(test_multi_fair_mutex_entry, NULL);
+ aio_co_schedule(ctx[i], co1);
+ }
+
+ g_usleep(seconds * 1000000);
+
+ atomic_mb_set(&now_stopping, true);
+ while (running > 0) {
+ g_usleep(100000);
+ }
+
+ join_aio_contexts();
+ g_test_message("%d iterations/second\n", counter / seconds);
+ g_assert_cmpint(counter, ==, atomic_counter);
+}
+
+static void test_multi_fair_mutex_1(void)
+{
+ test_multi_fair_mutex(NUM_CONTEXTS, 1);
+}
+
+static void test_multi_fair_mutex_10(void)
+{
+ test_multi_fair_mutex(NUM_CONTEXTS, 10);
+}
+#endif
+
+/* Same test with pthread mutexes, for performance comparison and
+ * portability. */
+
+static QemuMutex mutex;
+
+static void test_multi_mutex_entry(void *opaque)
+{
+ while (!atomic_mb_read(&now_stopping)) {
+ qemu_mutex_lock(&mutex);
+ counter++;
+ qemu_mutex_unlock(&mutex);
+ atomic_inc(&atomic_counter);
+ }
+ atomic_dec(&running);
+}
+
+static void test_multi_mutex(int threads, int seconds)
+{
+ int i;
+
+ qemu_mutex_init(&mutex);
+ counter = 0;
+ atomic_counter = 0;
+ now_stopping = false;
+
+ create_aio_contexts();
+ assert(threads <= NUM_CONTEXTS);
+ running = threads;
+ for (i = 0; i < threads; i++) {
+ Coroutine *co1 = qemu_coroutine_create(test_multi_mutex_entry, NULL);
+ aio_co_schedule(ctx[i], co1);
+ }
+
+ g_usleep(seconds * 1000000);
+
+ atomic_mb_set(&now_stopping, true);
+ while (running > 0) {
+ g_usleep(100000);
+ }
+
+ join_aio_contexts();
+ g_test_message("%d iterations/second\n", counter / seconds);
+ g_assert_cmpint(counter, ==, atomic_counter);
+}
+
+static void test_multi_mutex_1(void)
+{
+ test_multi_mutex(NUM_CONTEXTS, 1);
+}
+
+static void test_multi_mutex_10(void)
+{
+ test_multi_mutex(NUM_CONTEXTS, 10);
+}
+
/* End of tests. */
int main(int argc, char **argv)
@@ -290,10 +446,18 @@ int main(int argc, char **argv)
g_test_add_func("/aio/multi/schedule", test_multi_co_schedule_1);
g_test_add_func("/aio/multi/mutex/contended", test_multi_co_mutex_1);
g_test_add_func("/aio/multi/mutex/handoff", test_multi_co_mutex_2_3);
+#ifdef CONFIG_LINUX
+ g_test_add_func("/aio/multi/mutex/mcs", test_multi_fair_mutex_1);
+#endif
+ g_test_add_func("/aio/multi/mutex/pthread", test_multi_mutex_1);
} else {
g_test_add_func("/aio/multi/schedule", test_multi_co_schedule_10);
g_test_add_func("/aio/multi/mutex/contended", test_multi_co_mutex_10);
g_test_add_func("/aio/multi/mutex/handoff", test_multi_co_mutex_2_30);
+#ifdef CONFIG_LINUX
+ g_test_add_func("/aio/multi/mutex/mcs", test_multi_fair_mutex_10);
+#endif
+ g_test_add_func("/aio/multi/mutex/pthread", test_multi_mutex_10);
}
return g_test_run();
}