mirror of https://gitee.com/openkylin/qemu.git
461 lines
11 KiB
C
461 lines
11 KiB
C
/*
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* AioContext multithreading tests
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*
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* Copyright Red Hat, Inc. 2016
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*
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* Authors:
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* Paolo Bonzini <pbonzini@redhat.com>
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*
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* This work is licensed under the terms of the GNU LGPL, version 2 or later.
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* See the COPYING.LIB file in the top-level directory.
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*/
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#include "qemu/osdep.h"
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#include "block/aio.h"
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#include "qemu/coroutine.h"
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#include "qemu/thread.h"
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#include "qemu/error-report.h"
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#include "iothread.h"
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/* AioContext management */
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#define NUM_CONTEXTS 5
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static IOThread *threads[NUM_CONTEXTS];
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static AioContext *ctx[NUM_CONTEXTS];
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static __thread int id = -1;
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static QemuEvent done_event;
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/* Run a function synchronously on a remote iothread. */
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typedef struct CtxRunData {
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QEMUBHFunc *cb;
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void *arg;
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} CtxRunData;
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static void ctx_run_bh_cb(void *opaque)
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{
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CtxRunData *data = opaque;
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data->cb(data->arg);
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qemu_event_set(&done_event);
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}
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static void ctx_run(int i, QEMUBHFunc *cb, void *opaque)
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{
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CtxRunData data = {
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.cb = cb,
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.arg = opaque
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};
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qemu_event_reset(&done_event);
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aio_bh_schedule_oneshot(ctx[i], ctx_run_bh_cb, &data);
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qemu_event_wait(&done_event);
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}
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/* Starting the iothreads. */
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static void set_id_cb(void *opaque)
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{
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int *i = opaque;
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id = *i;
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}
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static void create_aio_contexts(void)
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{
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int i;
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for (i = 0; i < NUM_CONTEXTS; i++) {
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threads[i] = iothread_new();
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ctx[i] = iothread_get_aio_context(threads[i]);
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}
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qemu_event_init(&done_event, false);
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for (i = 0; i < NUM_CONTEXTS; i++) {
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ctx_run(i, set_id_cb, &i);
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}
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}
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/* Stopping the iothreads. */
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static void join_aio_contexts(void)
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{
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int i;
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for (i = 0; i < NUM_CONTEXTS; i++) {
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aio_context_ref(ctx[i]);
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}
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for (i = 0; i < NUM_CONTEXTS; i++) {
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iothread_join(threads[i]);
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}
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for (i = 0; i < NUM_CONTEXTS; i++) {
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aio_context_unref(ctx[i]);
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}
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qemu_event_destroy(&done_event);
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}
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/* Basic test for the stuff above. */
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static void test_lifecycle(void)
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{
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create_aio_contexts();
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join_aio_contexts();
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}
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/* aio_co_schedule test. */
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static Coroutine *to_schedule[NUM_CONTEXTS];
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static bool now_stopping;
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static int count_retry;
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static int count_here;
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static int count_other;
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static bool schedule_next(int n)
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{
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Coroutine *co;
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co = qatomic_xchg(&to_schedule[n], NULL);
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if (!co) {
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qatomic_inc(&count_retry);
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return false;
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}
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if (n == id) {
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qatomic_inc(&count_here);
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} else {
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qatomic_inc(&count_other);
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}
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aio_co_schedule(ctx[n], co);
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return true;
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}
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static void finish_cb(void *opaque)
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{
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schedule_next(id);
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}
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static coroutine_fn void test_multi_co_schedule_entry(void *opaque)
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{
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g_assert(to_schedule[id] == NULL);
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while (!qatomic_mb_read(&now_stopping)) {
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int n;
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n = g_test_rand_int_range(0, NUM_CONTEXTS);
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schedule_next(n);
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qatomic_mb_set(&to_schedule[id], qemu_coroutine_self());
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qemu_coroutine_yield();
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g_assert(to_schedule[id] == NULL);
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}
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}
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static void test_multi_co_schedule(int seconds)
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{
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int i;
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count_here = count_other = count_retry = 0;
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now_stopping = false;
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create_aio_contexts();
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for (i = 0; i < NUM_CONTEXTS; i++) {
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Coroutine *co1 = qemu_coroutine_create(test_multi_co_schedule_entry, NULL);
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aio_co_schedule(ctx[i], co1);
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}
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g_usleep(seconds * 1000000);
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qatomic_mb_set(&now_stopping, true);
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for (i = 0; i < NUM_CONTEXTS; i++) {
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ctx_run(i, finish_cb, NULL);
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to_schedule[i] = NULL;
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}
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join_aio_contexts();
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g_test_message("scheduled %d, queued %d, retry %d, total %d",
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count_other, count_here, count_retry,
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count_here + count_other + count_retry);
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}
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static void test_multi_co_schedule_1(void)
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{
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test_multi_co_schedule(1);
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}
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static void test_multi_co_schedule_10(void)
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{
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test_multi_co_schedule(10);
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}
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/* CoMutex thread-safety. */
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static uint32_t atomic_counter;
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static uint32_t running;
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static uint32_t counter;
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static CoMutex comutex;
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static void coroutine_fn test_multi_co_mutex_entry(void *opaque)
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{
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while (!qatomic_mb_read(&now_stopping)) {
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qemu_co_mutex_lock(&comutex);
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counter++;
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qemu_co_mutex_unlock(&comutex);
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/* Increase atomic_counter *after* releasing the mutex. Otherwise
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* there is a chance (it happens about 1 in 3 runs) that the iothread
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* exits before the coroutine is woken up, causing a spurious
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* assertion failure.
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*/
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qatomic_inc(&atomic_counter);
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}
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qatomic_dec(&running);
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}
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static void test_multi_co_mutex(int threads, int seconds)
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{
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int i;
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qemu_co_mutex_init(&comutex);
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counter = 0;
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atomic_counter = 0;
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now_stopping = false;
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create_aio_contexts();
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assert(threads <= NUM_CONTEXTS);
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running = threads;
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for (i = 0; i < threads; i++) {
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Coroutine *co1 = qemu_coroutine_create(test_multi_co_mutex_entry, NULL);
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aio_co_schedule(ctx[i], co1);
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}
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g_usleep(seconds * 1000000);
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qatomic_mb_set(&now_stopping, true);
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while (running > 0) {
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g_usleep(100000);
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}
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join_aio_contexts();
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g_test_message("%d iterations/second", counter / seconds);
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g_assert_cmpint(counter, ==, atomic_counter);
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}
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/* Testing with NUM_CONTEXTS threads focuses on the queue. The mutex however
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* is too contended (and the threads spend too much time in aio_poll)
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* to actually stress the handoff protocol.
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*/
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static void test_multi_co_mutex_1(void)
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{
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test_multi_co_mutex(NUM_CONTEXTS, 1);
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}
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static void test_multi_co_mutex_10(void)
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{
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test_multi_co_mutex(NUM_CONTEXTS, 10);
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}
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/* Testing with fewer threads stresses the handoff protocol too. Still, the
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* case where the locker _can_ pick up a handoff is very rare, happening
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* about 10 times in 1 million, so increase the runtime a bit compared to
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* other "quick" testcases that only run for 1 second.
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*/
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static void test_multi_co_mutex_2_3(void)
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{
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test_multi_co_mutex(2, 3);
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}
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static void test_multi_co_mutex_2_30(void)
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{
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test_multi_co_mutex(2, 30);
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}
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/* Same test with fair mutexes, for performance comparison. */
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#ifdef CONFIG_LINUX
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#include "qemu/futex.h"
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/* The nodes for the mutex reside in this structure (on which we try to avoid
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* false sharing). The head of the mutex is in the "mutex_head" variable.
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*/
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static struct {
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int next, locked;
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int padding[14];
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} nodes[NUM_CONTEXTS] __attribute__((__aligned__(64)));
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static int mutex_head = -1;
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static void mcs_mutex_lock(void)
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{
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int prev;
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nodes[id].next = -1;
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nodes[id].locked = 1;
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prev = qatomic_xchg(&mutex_head, id);
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if (prev != -1) {
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qatomic_set(&nodes[prev].next, id);
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qemu_futex_wait(&nodes[id].locked, 1);
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}
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}
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static void mcs_mutex_unlock(void)
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{
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int next;
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if (qatomic_read(&nodes[id].next) == -1) {
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if (qatomic_read(&mutex_head) == id &&
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qatomic_cmpxchg(&mutex_head, id, -1) == id) {
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/* Last item in the list, exit. */
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return;
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}
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while (qatomic_read(&nodes[id].next) == -1) {
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/* mcs_mutex_lock did the xchg, but has not updated
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* nodes[prev].next yet.
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*/
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}
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}
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/* Wake up the next in line. */
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next = qatomic_read(&nodes[id].next);
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nodes[next].locked = 0;
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qemu_futex_wake(&nodes[next].locked, 1);
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}
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static void test_multi_fair_mutex_entry(void *opaque)
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{
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while (!qatomic_mb_read(&now_stopping)) {
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mcs_mutex_lock();
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counter++;
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mcs_mutex_unlock();
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qatomic_inc(&atomic_counter);
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}
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qatomic_dec(&running);
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}
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static void test_multi_fair_mutex(int threads, int seconds)
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{
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int i;
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assert(mutex_head == -1);
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counter = 0;
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atomic_counter = 0;
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now_stopping = false;
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create_aio_contexts();
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assert(threads <= NUM_CONTEXTS);
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running = threads;
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for (i = 0; i < threads; i++) {
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Coroutine *co1 = qemu_coroutine_create(test_multi_fair_mutex_entry, NULL);
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aio_co_schedule(ctx[i], co1);
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}
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g_usleep(seconds * 1000000);
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qatomic_mb_set(&now_stopping, true);
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while (running > 0) {
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g_usleep(100000);
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}
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join_aio_contexts();
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g_test_message("%d iterations/second", counter / seconds);
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g_assert_cmpint(counter, ==, atomic_counter);
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}
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static void test_multi_fair_mutex_1(void)
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{
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test_multi_fair_mutex(NUM_CONTEXTS, 1);
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}
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static void test_multi_fair_mutex_10(void)
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{
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test_multi_fair_mutex(NUM_CONTEXTS, 10);
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}
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#endif
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/* Same test with pthread mutexes, for performance comparison and
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* portability. */
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static QemuMutex mutex;
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static void test_multi_mutex_entry(void *opaque)
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{
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while (!qatomic_mb_read(&now_stopping)) {
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qemu_mutex_lock(&mutex);
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counter++;
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qemu_mutex_unlock(&mutex);
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qatomic_inc(&atomic_counter);
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}
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qatomic_dec(&running);
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}
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static void test_multi_mutex(int threads, int seconds)
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{
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int i;
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qemu_mutex_init(&mutex);
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counter = 0;
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atomic_counter = 0;
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now_stopping = false;
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create_aio_contexts();
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assert(threads <= NUM_CONTEXTS);
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running = threads;
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for (i = 0; i < threads; i++) {
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Coroutine *co1 = qemu_coroutine_create(test_multi_mutex_entry, NULL);
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aio_co_schedule(ctx[i], co1);
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}
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g_usleep(seconds * 1000000);
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qatomic_mb_set(&now_stopping, true);
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while (running > 0) {
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g_usleep(100000);
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}
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join_aio_contexts();
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g_test_message("%d iterations/second", counter / seconds);
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g_assert_cmpint(counter, ==, atomic_counter);
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}
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static void test_multi_mutex_1(void)
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{
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test_multi_mutex(NUM_CONTEXTS, 1);
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}
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static void test_multi_mutex_10(void)
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{
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test_multi_mutex(NUM_CONTEXTS, 10);
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}
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/* End of tests. */
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int main(int argc, char **argv)
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{
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init_clocks(NULL);
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g_test_init(&argc, &argv, NULL);
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g_test_add_func("/aio/multi/lifecycle", test_lifecycle);
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if (g_test_quick()) {
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g_test_add_func("/aio/multi/schedule", test_multi_co_schedule_1);
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g_test_add_func("/aio/multi/mutex/contended", test_multi_co_mutex_1);
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g_test_add_func("/aio/multi/mutex/handoff", test_multi_co_mutex_2_3);
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#ifdef CONFIG_LINUX
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g_test_add_func("/aio/multi/mutex/mcs", test_multi_fair_mutex_1);
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#endif
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g_test_add_func("/aio/multi/mutex/pthread", test_multi_mutex_1);
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} else {
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g_test_add_func("/aio/multi/schedule", test_multi_co_schedule_10);
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g_test_add_func("/aio/multi/mutex/contended", test_multi_co_mutex_10);
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g_test_add_func("/aio/multi/mutex/handoff", test_multi_co_mutex_2_30);
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#ifdef CONFIG_LINUX
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g_test_add_func("/aio/multi/mutex/mcs", test_multi_fair_mutex_10);
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#endif
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g_test_add_func("/aio/multi/mutex/pthread", test_multi_mutex_10);
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}
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return g_test_run();
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}
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