block: vmdk - make ret variable usage clear

[qemu.git] / qemu-coroutine.c

diff --git a/qemu-coroutine.c b/qemu-coroutine.c
index 0f6e2685749584e0a52dd25e23d5207c84f03e61..525247b0501dd2eff6a2185ac9fff08e57c2c216 100644 (file)
--- a/qemu-coroutine.c
+++ b/qemu-coroutine.c
@@ -14,28 +14,105 @@
 
 #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_BATCH_SIZE = 64,
+};
+
+/** Free list to speed up creation */
+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 unsigned int alloc_pool_size;
+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 = qemu_coroutine_new();
+    Coroutine *co = NULL;
+
+    if (CONFIG_COROUTINE_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.
+                 */
+                alloc_pool_size = atomic_xchg(&release_pool_size, 0);
+                QSLIST_MOVE_ATOMIC(&alloc_pool, &release_pool);
+                co = QSLIST_FIRST(&alloc_pool);
+            }
+        }
+        if (co) {
+            QSLIST_REMOVE_HEAD(&alloc_pool, pool_next);
+            alloc_pool_size--;
+        }
+    }
+
+    if (!co) {
+        co = qemu_coroutine_new();
+    }
+
     co->entry = entry;
+    QTAILQ_INIT(&co->co_queue_wakeup);
     return co;
 }
 
+static void coroutine_delete(Coroutine *co)
+{
+    co->caller = NULL;
+
+    if (CONFIG_COROUTINE_POOL) {
+        if (release_pool_size < POOL_BATCH_SIZE * 2) {
+            QSLIST_INSERT_HEAD_ATOMIC(&release_pool, co, pool_next);
+            atomic_inc(&release_pool_size);
+            return;
+        }
+        if (alloc_pool_size < POOL_BATCH_SIZE) {
+            QSLIST_INSERT_HEAD(&alloc_pool, co, pool_next);
+            alloc_pool_size++;
+            return;
+        }
+    }
+
+    qemu_coroutine_delete(co);
+}
+
 static void coroutine_swap(Coroutine *from, Coroutine *to)
 {
     CoroutineAction ret;
 
     ret = qemu_coroutine_switch(from, to, COROUTINE_YIELD);
 
+    qemu_co_queue_run_restart(to);
+
     switch (ret) {
     case COROUTINE_YIELD:
         return;
     case COROUTINE_TERMINATE:
         trace_qemu_coroutine_terminate(to);
-        qemu_coroutine_delete(to);
+        coroutine_delete(to);
         return;
     default:
         abort();