aio_co_wake provides the infrastructure to start a coroutine on a "home" AioContext. It will be used by CoMutex and CoQueue, so that coroutines don't jump from one context to another when they go to sleep on a mutex or waitqueue. However, it can also be used as a more efficient alternative to one-shot bottom halves, and saves the effort of tracking which AioContext a coroutine is running on. aio_co_schedule is the part of aio_co_wake that starts a coroutine on a remove AioContext, but it is also useful to implement e.g. bdrv_set_aio_context callbacks. The implementation of aio_co_schedule is based on a lock-free multiple-producer, single-consumer queue. The multiple producers use cmpxchg to add to a LIFO stack. The consumer (a per-AioContext bottom half) grabs all items added so far, inverts the list to make it FIFO, and goes through it one item at a time until it's empty. The data structure was inspired by OSv, which uses it in the very code we'll "port" to QEMU for the thread-safe CoMutex. Most of the new code is really tests. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Message-id: 20170213135235.12274-3-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
214 lines
4.3 KiB
C
214 lines
4.3 KiB
C
/*
|
|
* AioContext multithreading tests
|
|
*
|
|
* Copyright Red Hat, Inc. 2016
|
|
*
|
|
* Authors:
|
|
* Paolo Bonzini <pbonzini@redhat.com>
|
|
*
|
|
* This work is licensed under the terms of the GNU LGPL, version 2 or later.
|
|
* See the COPYING.LIB file in the top-level directory.
|
|
*/
|
|
|
|
#include "qemu/osdep.h"
|
|
#include <glib.h>
|
|
#include "block/aio.h"
|
|
#include "qapi/error.h"
|
|
#include "qemu/coroutine.h"
|
|
#include "qemu/thread.h"
|
|
#include "qemu/error-report.h"
|
|
#include "iothread.h"
|
|
|
|
/* AioContext management */
|
|
|
|
#define NUM_CONTEXTS 5
|
|
|
|
static IOThread *threads[NUM_CONTEXTS];
|
|
static AioContext *ctx[NUM_CONTEXTS];
|
|
static __thread int id = -1;
|
|
|
|
static QemuEvent done_event;
|
|
|
|
/* Run a function synchronously on a remote iothread. */
|
|
|
|
typedef struct CtxRunData {
|
|
QEMUBHFunc *cb;
|
|
void *arg;
|
|
} CtxRunData;
|
|
|
|
static void ctx_run_bh_cb(void *opaque)
|
|
{
|
|
CtxRunData *data = opaque;
|
|
|
|
data->cb(data->arg);
|
|
qemu_event_set(&done_event);
|
|
}
|
|
|
|
static void ctx_run(int i, QEMUBHFunc *cb, void *opaque)
|
|
{
|
|
CtxRunData data = {
|
|
.cb = cb,
|
|
.arg = opaque
|
|
};
|
|
|
|
qemu_event_reset(&done_event);
|
|
aio_bh_schedule_oneshot(ctx[i], ctx_run_bh_cb, &data);
|
|
qemu_event_wait(&done_event);
|
|
}
|
|
|
|
/* Starting the iothreads. */
|
|
|
|
static void set_id_cb(void *opaque)
|
|
{
|
|
int *i = opaque;
|
|
|
|
id = *i;
|
|
}
|
|
|
|
static void create_aio_contexts(void)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < NUM_CONTEXTS; i++) {
|
|
threads[i] = iothread_new();
|
|
ctx[i] = iothread_get_aio_context(threads[i]);
|
|
}
|
|
|
|
qemu_event_init(&done_event, false);
|
|
for (i = 0; i < NUM_CONTEXTS; i++) {
|
|
ctx_run(i, set_id_cb, &i);
|
|
}
|
|
}
|
|
|
|
/* Stopping the iothreads. */
|
|
|
|
static void join_aio_contexts(void)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < NUM_CONTEXTS; i++) {
|
|
aio_context_ref(ctx[i]);
|
|
}
|
|
for (i = 0; i < NUM_CONTEXTS; i++) {
|
|
iothread_join(threads[i]);
|
|
}
|
|
for (i = 0; i < NUM_CONTEXTS; i++) {
|
|
aio_context_unref(ctx[i]);
|
|
}
|
|
qemu_event_destroy(&done_event);
|
|
}
|
|
|
|
/* Basic test for the stuff above. */
|
|
|
|
static void test_lifecycle(void)
|
|
{
|
|
create_aio_contexts();
|
|
join_aio_contexts();
|
|
}
|
|
|
|
/* aio_co_schedule test. */
|
|
|
|
static Coroutine *to_schedule[NUM_CONTEXTS];
|
|
|
|
static bool now_stopping;
|
|
|
|
static int count_retry;
|
|
static int count_here;
|
|
static int count_other;
|
|
|
|
static bool schedule_next(int n)
|
|
{
|
|
Coroutine *co;
|
|
|
|
co = atomic_xchg(&to_schedule[n], NULL);
|
|
if (!co) {
|
|
atomic_inc(&count_retry);
|
|
return false;
|
|
}
|
|
|
|
if (n == id) {
|
|
atomic_inc(&count_here);
|
|
} else {
|
|
atomic_inc(&count_other);
|
|
}
|
|
|
|
aio_co_schedule(ctx[n], co);
|
|
return true;
|
|
}
|
|
|
|
static void finish_cb(void *opaque)
|
|
{
|
|
schedule_next(id);
|
|
}
|
|
|
|
static coroutine_fn void test_multi_co_schedule_entry(void *opaque)
|
|
{
|
|
g_assert(to_schedule[id] == NULL);
|
|
atomic_mb_set(&to_schedule[id], qemu_coroutine_self());
|
|
|
|
while (!atomic_mb_read(&now_stopping)) {
|
|
int n;
|
|
|
|
n = g_test_rand_int_range(0, NUM_CONTEXTS);
|
|
schedule_next(n);
|
|
qemu_coroutine_yield();
|
|
|
|
g_assert(to_schedule[id] == NULL);
|
|
atomic_mb_set(&to_schedule[id], qemu_coroutine_self());
|
|
}
|
|
}
|
|
|
|
|
|
static void test_multi_co_schedule(int seconds)
|
|
{
|
|
int i;
|
|
|
|
count_here = count_other = count_retry = 0;
|
|
now_stopping = false;
|
|
|
|
create_aio_contexts();
|
|
for (i = 0; i < NUM_CONTEXTS; i++) {
|
|
Coroutine *co1 = qemu_coroutine_create(test_multi_co_schedule_entry, NULL);
|
|
aio_co_schedule(ctx[i], co1);
|
|
}
|
|
|
|
g_usleep(seconds * 1000000);
|
|
|
|
atomic_mb_set(&now_stopping, true);
|
|
for (i = 0; i < NUM_CONTEXTS; i++) {
|
|
ctx_run(i, finish_cb, NULL);
|
|
to_schedule[i] = NULL;
|
|
}
|
|
|
|
join_aio_contexts();
|
|
g_test_message("scheduled %d, queued %d, retry %d, total %d\n",
|
|
count_other, count_here, count_retry,
|
|
count_here + count_other + count_retry);
|
|
}
|
|
|
|
static void test_multi_co_schedule_1(void)
|
|
{
|
|
test_multi_co_schedule(1);
|
|
}
|
|
|
|
static void test_multi_co_schedule_10(void)
|
|
{
|
|
test_multi_co_schedule(10);
|
|
}
|
|
|
|
/* End of tests. */
|
|
|
|
int main(int argc, char **argv)
|
|
{
|
|
init_clocks();
|
|
|
|
g_test_init(&argc, &argv, NULL);
|
|
g_test_add_func("/aio/multi/lifecycle", test_lifecycle);
|
|
if (g_test_quick()) {
|
|
g_test_add_func("/aio/multi/schedule", test_multi_co_schedule_1);
|
|
} else {
|
|
g_test_add_func("/aio/multi/schedule", test_multi_co_schedule_10);
|
|
}
|
|
return g_test_run();
|
|
}
|