* Contributions after 2012-01-13 are licensed under the terms of the
* GNU GPL, version 2 or (at your option) any later version.
*/
+#include "qemu/osdep.h"
#include "qemu-common.h"
-#include "qemu-queue.h"
-#include "qemu-thread.h"
-#include "osdep.h"
-#include "qemu-coroutine.h"
+#include "qemu/queue.h"
+#include "qemu/thread.h"
+#include "qemu/coroutine.h"
#include "trace.h"
-#include "block_int.h"
-#include "event_notifier.h"
-#include "thread-pool.h"
+#include "block/thread-pool.h"
+#include "qemu/main-loop.h"
-static void do_spawn_thread(void);
+static void do_spawn_thread(ThreadPool *pool);
typedef struct ThreadPoolElement ThreadPoolElement;
THREAD_QUEUED,
THREAD_ACTIVE,
THREAD_DONE,
- THREAD_CANCELED,
};
struct ThreadPoolElement {
- BlockDriverAIOCB common;
+ BlockAIOCB common;
+ ThreadPool *pool;
ThreadPoolFunc *func;
void *arg;
QLIST_ENTRY(ThreadPoolElement) all;
};
-static EventNotifier notifier;
-static QemuMutex lock;
-static QemuCond check_cancel;
-static QemuSemaphore sem;
-static int max_threads = 64;
-static QEMUBH *new_thread_bh;
-
-/* The following variables are protected by the global mutex. */
-static QLIST_HEAD(, ThreadPoolElement) head;
-
-/* The following variables are protected by lock. */
-static QTAILQ_HEAD(, ThreadPoolElement) request_list;
-static int cur_threads;
-static int idle_threads;
-static int new_threads; /* backlog of threads we need to create */
-static int pending_threads; /* threads created but not running yet */
-static int pending_cancellations; /* whether we need a cond_broadcast */
-
-static void *worker_thread(void *unused)
+struct ThreadPool {
+ AioContext *ctx;
+ QEMUBH *completion_bh;
+ QemuMutex lock;
+ QemuCond worker_stopped;
+ QemuSemaphore sem;
+ int max_threads;
+ QEMUBH *new_thread_bh;
+
+ /* The following variables are only accessed from one AioContext. */
+ QLIST_HEAD(, ThreadPoolElement) head;
+
+ /* The following variables are protected by lock. */
+ QTAILQ_HEAD(, ThreadPoolElement) request_list;
+ int cur_threads;
+ int idle_threads;
+ int new_threads; /* backlog of threads we need to create */
+ int pending_threads; /* threads created but not running yet */
+ bool stopping;
+};
+
+static void *worker_thread(void *opaque)
{
- qemu_mutex_lock(&lock);
- pending_threads--;
- do_spawn_thread();
+ ThreadPool *pool = opaque;
+
+ qemu_mutex_lock(&pool->lock);
+ pool->pending_threads--;
+ do_spawn_thread(pool);
- while (1) {
+ while (!pool->stopping) {
ThreadPoolElement *req;
int ret;
do {
- idle_threads++;
- qemu_mutex_unlock(&lock);
- ret = qemu_sem_timedwait(&sem, 10000);
- qemu_mutex_lock(&lock);
- idle_threads--;
- } while (ret == -1 && !QTAILQ_EMPTY(&request_list));
- if (ret == -1) {
+ pool->idle_threads++;
+ qemu_mutex_unlock(&pool->lock);
+ ret = qemu_sem_timedwait(&pool->sem, 10000);
+ qemu_mutex_lock(&pool->lock);
+ pool->idle_threads--;
+ } while (ret == -1 && !QTAILQ_EMPTY(&pool->request_list));
+ if (ret == -1 || pool->stopping) {
break;
}
- req = QTAILQ_FIRST(&request_list);
- QTAILQ_REMOVE(&request_list, req, reqs);
+ req = QTAILQ_FIRST(&pool->request_list);
+ QTAILQ_REMOVE(&pool->request_list, req, reqs);
req->state = THREAD_ACTIVE;
- qemu_mutex_unlock(&lock);
+ qemu_mutex_unlock(&pool->lock);
ret = req->func(req->arg);
smp_wmb();
req->state = THREAD_DONE;
- qemu_mutex_lock(&lock);
- if (pending_cancellations) {
- qemu_cond_broadcast(&check_cancel);
- }
+ qemu_mutex_lock(&pool->lock);
- event_notifier_set(¬ifier);
+ qemu_bh_schedule(pool->completion_bh);
}
- cur_threads--;
- qemu_mutex_unlock(&lock);
+ pool->cur_threads--;
+ qemu_cond_signal(&pool->worker_stopped);
+ qemu_mutex_unlock(&pool->lock);
return NULL;
}
-static void do_spawn_thread(void)
+static void do_spawn_thread(ThreadPool *pool)
{
QemuThread t;
/* Runs with lock taken. */
- if (!new_threads) {
+ if (!pool->new_threads) {
return;
}
- new_threads--;
- pending_threads++;
+ pool->new_threads--;
+ pool->pending_threads++;
- qemu_thread_create(&t, worker_thread, NULL, QEMU_THREAD_DETACHED);
+ qemu_thread_create(&t, "worker", worker_thread, pool, QEMU_THREAD_DETACHED);
}
static void spawn_thread_bh_fn(void *opaque)
{
- qemu_mutex_lock(&lock);
- do_spawn_thread();
- qemu_mutex_unlock(&lock);
+ ThreadPool *pool = opaque;
+
+ qemu_mutex_lock(&pool->lock);
+ do_spawn_thread(pool);
+ qemu_mutex_unlock(&pool->lock);
}
-static void spawn_thread(void)
+static void spawn_thread(ThreadPool *pool)
{
- cur_threads++;
- new_threads++;
+ pool->cur_threads++;
+ pool->new_threads++;
/* If there are threads being created, they will spawn new workers, so
* we don't spend time creating many threads in a loop holding a mutex or
* starving the current vcpu.
* If there are no idle threads, ask the main thread to create one, so we
* inherit the correct affinity instead of the vcpu affinity.
*/
- if (!pending_threads) {
- qemu_bh_schedule(new_thread_bh);
+ if (!pool->pending_threads) {
+ qemu_bh_schedule(pool->new_thread_bh);
}
}
-static void event_notifier_ready(EventNotifier *notifier)
+static void thread_pool_completion_bh(void *opaque)
{
+ ThreadPool *pool = opaque;
ThreadPoolElement *elem, *next;
- event_notifier_test_and_clear(notifier);
restart:
- QLIST_FOREACH_SAFE(elem, &head, all, next) {
- if (elem->state != THREAD_CANCELED && elem->state != THREAD_DONE) {
+ QLIST_FOREACH_SAFE(elem, &pool->head, all, next) {
+ if (elem->state != THREAD_DONE) {
continue;
}
- if (elem->state == THREAD_DONE) {
- trace_thread_pool_complete(elem, elem->common.opaque, elem->ret);
- }
- if (elem->state == THREAD_DONE && elem->common.cb) {
- QLIST_REMOVE(elem, all);
+
+ trace_thread_pool_complete(pool, elem, elem->common.opaque,
+ elem->ret);
+ QLIST_REMOVE(elem, all);
+
+ if (elem->common.cb) {
/* Read state before ret. */
smp_rmb();
+
+ /* Schedule ourselves in case elem->common.cb() calls aio_poll() to
+ * wait for another request that completed at the same time.
+ */
+ qemu_bh_schedule(pool->completion_bh);
+
elem->common.cb(elem->common.opaque, elem->ret);
- qemu_aio_release(elem);
+ qemu_aio_unref(elem);
goto restart;
} else {
- /* remove the request */
- QLIST_REMOVE(elem, all);
- qemu_aio_release(elem);
+ qemu_aio_unref(elem);
}
}
}
-static int thread_pool_active(EventNotifier *notifier)
-{
- return !QLIST_EMPTY(&head);
-}
-
-static void thread_pool_cancel(BlockDriverAIOCB *acb)
+static void thread_pool_cancel(BlockAIOCB *acb)
{
ThreadPoolElement *elem = (ThreadPoolElement *)acb;
+ ThreadPool *pool = elem->pool;
trace_thread_pool_cancel(elem, elem->common.opaque);
- qemu_mutex_lock(&lock);
+ qemu_mutex_lock(&pool->lock);
if (elem->state == THREAD_QUEUED &&
/* No thread has yet started working on elem. we can try to "steal"
* the item from the worker if we can get a signal from the
* semaphore. Because this is non-blocking, we can do it with
* the lock taken and ensure that elem will remain THREAD_QUEUED.
*/
- qemu_sem_timedwait(&sem, 0) == 0) {
- QTAILQ_REMOVE(&request_list, elem, reqs);
- elem->state = THREAD_CANCELED;
- event_notifier_set(¬ifier);
- } else {
- pending_cancellations++;
- while (elem->state != THREAD_CANCELED && elem->state != THREAD_DONE) {
- qemu_cond_wait(&check_cancel, &lock);
- }
- pending_cancellations--;
+ qemu_sem_timedwait(&pool->sem, 0) == 0) {
+ QTAILQ_REMOVE(&pool->request_list, elem, reqs);
+ qemu_bh_schedule(pool->completion_bh);
+
+ elem->state = THREAD_DONE;
+ elem->ret = -ECANCELED;
}
- qemu_mutex_unlock(&lock);
+
+ qemu_mutex_unlock(&pool->lock);
+}
+
+static AioContext *thread_pool_get_aio_context(BlockAIOCB *acb)
+{
+ ThreadPoolElement *elem = (ThreadPoolElement *)acb;
+ ThreadPool *pool = elem->pool;
+ return pool->ctx;
}
static const AIOCBInfo thread_pool_aiocb_info = {
.aiocb_size = sizeof(ThreadPoolElement),
- .cancel = thread_pool_cancel,
+ .cancel_async = thread_pool_cancel,
+ .get_aio_context = thread_pool_get_aio_context,
};
-BlockDriverAIOCB *thread_pool_submit_aio(ThreadPoolFunc *func, void *arg,
- BlockDriverCompletionFunc *cb, void *opaque)
+BlockAIOCB *thread_pool_submit_aio(ThreadPool *pool,
+ ThreadPoolFunc *func, void *arg,
+ BlockCompletionFunc *cb, void *opaque)
{
ThreadPoolElement *req;
req->func = func;
req->arg = arg;
req->state = THREAD_QUEUED;
+ req->pool = pool;
- QLIST_INSERT_HEAD(&head, req, all);
+ QLIST_INSERT_HEAD(&pool->head, req, all);
- trace_thread_pool_submit(req, arg);
+ trace_thread_pool_submit(pool, req, arg);
- qemu_mutex_lock(&lock);
- if (idle_threads == 0 && cur_threads < max_threads) {
- spawn_thread();
+ qemu_mutex_lock(&pool->lock);
+ if (pool->idle_threads == 0 && pool->cur_threads < pool->max_threads) {
+ spawn_thread(pool);
}
- QTAILQ_INSERT_TAIL(&request_list, req, reqs);
- qemu_mutex_unlock(&lock);
- qemu_sem_post(&sem);
+ QTAILQ_INSERT_TAIL(&pool->request_list, req, reqs);
+ qemu_mutex_unlock(&pool->lock);
+ qemu_sem_post(&pool->sem);
return &req->common;
}
qemu_coroutine_enter(co->co, NULL);
}
-int coroutine_fn thread_pool_submit_co(ThreadPoolFunc *func, void *arg)
+int coroutine_fn thread_pool_submit_co(ThreadPool *pool, ThreadPoolFunc *func,
+ void *arg)
{
ThreadPoolCo tpc = { .co = qemu_coroutine_self(), .ret = -EINPROGRESS };
assert(qemu_in_coroutine());
- thread_pool_submit_aio(func, arg, thread_pool_co_cb, &tpc);
+ thread_pool_submit_aio(pool, func, arg, thread_pool_co_cb, &tpc);
qemu_coroutine_yield();
return tpc.ret;
}
-void thread_pool_submit(ThreadPoolFunc *func, void *arg)
+void thread_pool_submit(ThreadPool *pool, ThreadPoolFunc *func, void *arg)
{
- thread_pool_submit_aio(func, arg, NULL, NULL);
+ thread_pool_submit_aio(pool, func, arg, NULL, NULL);
}
-static void thread_pool_init(void)
+static void thread_pool_init_one(ThreadPool *pool, AioContext *ctx)
{
- QLIST_INIT(&head);
- event_notifier_init(¬ifier, false);
- qemu_mutex_init(&lock);
- qemu_cond_init(&check_cancel);
- qemu_sem_init(&sem, 0);
- qemu_aio_set_event_notifier(¬ifier, event_notifier_ready,
- thread_pool_active);
-
- QTAILQ_INIT(&request_list);
- new_thread_bh = qemu_bh_new(spawn_thread_bh_fn, NULL);
+ if (!ctx) {
+ ctx = qemu_get_aio_context();
+ }
+
+ memset(pool, 0, sizeof(*pool));
+ pool->ctx = ctx;
+ pool->completion_bh = aio_bh_new(ctx, thread_pool_completion_bh, pool);
+ qemu_mutex_init(&pool->lock);
+ qemu_cond_init(&pool->worker_stopped);
+ qemu_sem_init(&pool->sem, 0);
+ pool->max_threads = 64;
+ pool->new_thread_bh = aio_bh_new(ctx, spawn_thread_bh_fn, pool);
+
+ QLIST_INIT(&pool->head);
+ QTAILQ_INIT(&pool->request_list);
}
-block_init(thread_pool_init)
+ThreadPool *thread_pool_new(AioContext *ctx)
+{
+ ThreadPool *pool = g_new(ThreadPool, 1);
+ thread_pool_init_one(pool, ctx);
+ return pool;
+}
+
+void thread_pool_free(ThreadPool *pool)
+{
+ if (!pool) {
+ return;
+ }
+
+ assert(QLIST_EMPTY(&pool->head));
+
+ qemu_mutex_lock(&pool->lock);
+
+ /* Stop new threads from spawning */
+ qemu_bh_delete(pool->new_thread_bh);
+ pool->cur_threads -= pool->new_threads;
+ pool->new_threads = 0;
+
+ /* Wait for worker threads to terminate */
+ pool->stopping = true;
+ while (pool->cur_threads > 0) {
+ qemu_sem_post(&pool->sem);
+ qemu_cond_wait(&pool->worker_stopped, &pool->lock);
+ }
+
+ qemu_mutex_unlock(&pool->lock);
+
+ qemu_bh_delete(pool->completion_bh);
+ qemu_sem_destroy(&pool->sem);
+ qemu_cond_destroy(&pool->worker_stopped);
+ qemu_mutex_destroy(&pool->lock);
+ g_free(pool);
+}
projects / qemu.git / blobdiff