#include "trace.h"
#include "qemu-common.h"
#include "qemu/thread.h"
+#include "qemu/atomic.h"
#include "block/coroutine.h"
#include "block/coroutine_int.h"
enum {
- POOL_DEFAULT_SIZE = 64,
+ POOL_BATCH_SIZE = 64,
};
/** Free list to speed up creation */
-static QemuMutex pool_lock;
-static QSLIST_HEAD(, Coroutine) pool = QSLIST_HEAD_INITIALIZER(pool);
-static unsigned int pool_size;
-static unsigned int pool_max_size = POOL_DEFAULT_SIZE;
+static QSLIST_HEAD(, Coroutine) release_pool = QSLIST_HEAD_INITIALIZER(pool);
+static unsigned int release_pool_size;
+static __thread QSLIST_HEAD(, Coroutine) alloc_pool = QSLIST_HEAD_INITIALIZER(pool);
+static __thread Notifier coroutine_pool_cleanup_notifier;
+
+static void coroutine_pool_cleanup(Notifier *n, void *value)
+{
+ Coroutine *co;
+ Coroutine *tmp;
+
+ QSLIST_FOREACH_SAFE(co, &alloc_pool, pool_next, tmp) {
+ QSLIST_REMOVE_HEAD(&alloc_pool, pool_next);
+ qemu_coroutine_delete(co);
+ }
+}
Coroutine *qemu_coroutine_create(CoroutineEntry *entry)
{
Coroutine *co = NULL;
if (CONFIG_COROUTINE_POOL) {
- qemu_mutex_lock(&pool_lock);
- co = QSLIST_FIRST(&pool);
+ co = QSLIST_FIRST(&alloc_pool);
+ if (!co) {
+ if (release_pool_size > POOL_BATCH_SIZE) {
+ /* Slow path; a good place to register the destructor, too. */
+ if (!coroutine_pool_cleanup_notifier.notify) {
+ coroutine_pool_cleanup_notifier.notify = coroutine_pool_cleanup;
+ qemu_thread_atexit_add(&coroutine_pool_cleanup_notifier);
+ }
+
+ /* This is not exact; there could be a little skew between
+ * release_pool_size and the actual size of release_pool. But
+ * it is just a heuristic, it does not need to be perfect.
+ */
+ release_pool_size = 0;
+ QSLIST_MOVE_ATOMIC(&alloc_pool, &release_pool);
+ co = QSLIST_FIRST(&alloc_pool);
+ }
+ }
if (co) {
- QSLIST_REMOVE_HEAD(&pool, pool_next);
- pool_size--;
+ QSLIST_REMOVE_HEAD(&alloc_pool, pool_next);
}
- qemu_mutex_unlock(&pool_lock);
}
if (!co) {
static void coroutine_delete(Coroutine *co)
{
+ co->caller = NULL;
+
if (CONFIG_COROUTINE_POOL) {
- qemu_mutex_lock(&pool_lock);
- if (pool_size < pool_max_size) {
- QSLIST_INSERT_HEAD(&pool, co, pool_next);
- co->caller = NULL;
- pool_size++;
- qemu_mutex_unlock(&pool_lock);
+ if (release_pool_size < POOL_BATCH_SIZE * 2) {
+ QSLIST_INSERT_HEAD_ATOMIC(&release_pool, co, pool_next);
+ atomic_inc(&release_pool_size);
return;
}
- qemu_mutex_unlock(&pool_lock);
}
qemu_coroutine_delete(co);
}
-static void __attribute__((constructor)) coroutine_pool_init(void)
-{
- qemu_mutex_init(&pool_lock);
-}
-
-static void __attribute__((destructor)) coroutine_pool_cleanup(void)
-{
- Coroutine *co;
- Coroutine *tmp;
-
- QSLIST_FOREACH_SAFE(co, &pool, pool_next, tmp) {
- QSLIST_REMOVE_HEAD(&pool, pool_next);
- qemu_coroutine_delete(co);
- }
-
- qemu_mutex_destroy(&pool_lock);
-}
-
static void coroutine_swap(Coroutine *from, Coroutine *to)
{
CoroutineAction ret;
void qemu_coroutine_adjust_pool_size(int n)
{
- qemu_mutex_lock(&pool_lock);
-
- pool_max_size += n;
-
- /* Callers should never take away more than they added */
- assert(pool_max_size >= POOL_DEFAULT_SIZE);
-
- /* Trim oversized pool down to new max */
- while (pool_size > pool_max_size) {
- Coroutine *co = QSLIST_FIRST(&pool);
- QSLIST_REMOVE_HEAD(&pool, pool_next);
- pool_size--;
- qemu_coroutine_delete(co);
- }
-
- qemu_mutex_unlock(&pool_lock);
}