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authorStefan Hajnoczi <stefanha@redhat.com>2013-03-07 13:41:45 +0100
committerStefan Hajnoczi <stefanha@redhat.com>2013-03-15 16:07:50 +0100
commitb811203cf2fbf83e26f8e8feb2c77784259a4cbd (patch)
tree39236a7be710c49d3df65d921e0faa4a63cf8ef1 /thread-pool.c
parent5f3aa1ff4781f39e05b9892d58319a09fedc8918 (diff)
downloadqemu-arm-b811203cf2fbf83e26f8e8feb2c77784259a4cbd.tar.gz
threadpool: move globals into struct ThreadPool
Move global variables into a struct so multiple thread pools can be supported in the future. This patch does not change thread-pool.h interfaces. There is still a global thread pool and it is not yet possible to create/destroy individual thread pools. Moving the variables into a struct first makes later patches easier to review. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'thread-pool.c')
-rw-r--r--thread-pool.c190
1 files changed, 110 insertions, 80 deletions
diff --git a/thread-pool.c b/thread-pool.c
index e3ca64d790..a0aecd08fe 100644
--- a/thread-pool.c
+++ b/thread-pool.c
@@ -24,7 +24,9 @@
#include "qemu/event_notifier.h"
#include "block/thread-pool.h"
-static void do_spawn_thread(void);
+typedef struct ThreadPool ThreadPool;
+
+static void do_spawn_thread(ThreadPool *pool);
typedef struct ThreadPoolElement ThreadPoolElement;
@@ -37,6 +39,7 @@ enum ThreadState {
struct ThreadPoolElement {
BlockDriverAIOCB common;
+ ThreadPool *pool;
ThreadPoolFunc *func;
void *arg;
@@ -54,49 +57,56 @@ struct ThreadPoolElement {
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 {
+ EventNotifier notifier;
+ QemuMutex lock;
+ QemuCond check_cancel;
+ 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 */
+ int pending_cancellations; /* whether we need a cond_broadcast */
+};
+
+/* Currently there is only one thread pool instance. */
+static ThreadPool global_pool;
+
+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) {
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));
+ 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) {
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);
@@ -105,45 +115,47 @@ static void *worker_thread(void *unused)
smp_wmb();
req->state = THREAD_DONE;
- qemu_mutex_lock(&lock);
- if (pending_cancellations) {
- qemu_cond_broadcast(&check_cancel);
+ qemu_mutex_lock(&pool->lock);
+ if (pool->pending_cancellations) {
+ qemu_cond_broadcast(&pool->check_cancel);
}
- event_notifier_set(&notifier);
+ event_notifier_set(&pool->notifier);
}
- cur_threads--;
- qemu_mutex_unlock(&lock);
+ pool->cur_threads--;
+ 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_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.
@@ -151,23 +163,25 @@ static void spawn_thread(void)
* 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)
{
+ ThreadPool *pool = container_of(notifier, ThreadPool, notifier);
ThreadPoolElement *elem, *next;
event_notifier_test_and_clear(notifier);
restart:
- QLIST_FOREACH_SAFE(elem, &head, all, next) {
+ QLIST_FOREACH_SAFE(elem, &pool->head, all, next) {
if (elem->state != THREAD_CANCELED && elem->state != THREAD_DONE) {
continue;
}
if (elem->state == THREAD_DONE) {
- trace_thread_pool_complete(elem, elem->common.opaque, elem->ret);
+ trace_thread_pool_complete(pool, elem, elem->common.opaque,
+ elem->ret);
}
if (elem->state == THREAD_DONE && elem->common.cb) {
QLIST_REMOVE(elem, all);
@@ -186,34 +200,36 @@ restart:
static int thread_pool_active(EventNotifier *notifier)
{
- return !QLIST_EMPTY(&head);
+ ThreadPool *pool = container_of(notifier, ThreadPool, notifier);
+ return !QLIST_EMPTY(&pool->head);
}
static void thread_pool_cancel(BlockDriverAIOCB *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);
+ qemu_sem_timedwait(&pool->sem, 0) == 0) {
+ QTAILQ_REMOVE(&pool->request_list, elem, reqs);
elem->state = THREAD_CANCELED;
- event_notifier_set(&notifier);
+ event_notifier_set(&pool->notifier);
} else {
- pending_cancellations++;
+ pool->pending_cancellations++;
while (elem->state != THREAD_CANCELED && elem->state != THREAD_DONE) {
- qemu_cond_wait(&check_cancel, &lock);
+ qemu_cond_wait(&pool->check_cancel, &pool->lock);
}
- pending_cancellations--;
+ pool->pending_cancellations--;
}
- qemu_mutex_unlock(&lock);
+ qemu_mutex_unlock(&pool->lock);
}
static const AIOCBInfo thread_pool_aiocb_info = {
@@ -224,24 +240,26 @@ static const AIOCBInfo thread_pool_aiocb_info = {
BlockDriverAIOCB *thread_pool_submit_aio(ThreadPoolFunc *func, void *arg,
BlockDriverCompletionFunc *cb, void *opaque)
{
+ ThreadPool *pool = &global_pool;
ThreadPoolElement *req;
req = qemu_aio_get(&thread_pool_aiocb_info, NULL, cb, opaque);
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;
}
@@ -272,18 +290,30 @@ void thread_pool_submit(ThreadPoolFunc *func, void *arg)
thread_pool_submit_aio(func, arg, NULL, NULL);
}
+static void thread_pool_init_one(ThreadPool *pool, AioContext *ctx)
+{
+ if (!ctx) {
+ ctx = qemu_get_aio_context();
+ }
+
+ memset(pool, 0, sizeof(*pool));
+ event_notifier_init(&pool->notifier, false);
+ qemu_mutex_init(&pool->lock);
+ qemu_cond_init(&pool->check_cancel);
+ 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);
+
+ aio_set_event_notifier(ctx, &pool->notifier, event_notifier_ready,
+ thread_pool_active);
+}
+
static void thread_pool_init(void)
{
- QLIST_INIT(&head);
- event_notifier_init(&notifier, false);
- qemu_mutex_init(&lock);
- qemu_cond_init(&check_cancel);
- qemu_sem_init(&sem, 0);
- qemu_aio_set_event_notifier(&notifier, event_notifier_ready,
- thread_pool_active);
-
- QTAILQ_INIT(&request_list);
- new_thread_bh = qemu_bh_new(spawn_thread_bh_fn, NULL);
+ thread_pool_init_one(&global_pool, NULL);
}
block_init(thread_pool_init)