block/parallels: provide _co_readv routine for parallels format driver

[mirror_qemu.git] / qemu-coroutine.c

diff --git a/qemu-coroutine.c b/qemu-coroutine.c
index 470852100af1eb58e69f44d91cf29a11df7cff93..c17a92b107e8e7064b8616a2f46553ba9bac614d 100644 (file)
--- a/qemu-coroutine.c
+++ b/qemu-coroutine.c
@@ -15,31 +15,59 @@
 #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 {
-    /* Maximum free pool size prevents holding too many freed coroutines */
-    POOL_MAX_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 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 = 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.
+                 */
+                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(&pool, pool_next);
-            pool_size--;
+            QSLIST_REMOVE_HEAD(&alloc_pool, pool_next);
+            alloc_pool_size--;
         }
-        qemu_mutex_unlock(&pool_lock);
     }
 
     if (!co) {
@@ -53,75 +81,54 @@ Coroutine *qemu_coroutine_create(CoroutineEntry *entry)
 
 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;
+        }
+        if (alloc_pool_size < POOL_BATCH_SIZE) {
+            QSLIST_INSERT_HEAD(&alloc_pool, co, pool_next);
+            alloc_pool_size++;
             return;
         }
-        qemu_mutex_unlock(&pool_lock);
     }
 
     qemu_coroutine_delete(co);
 }
 
-static void __attribute__((constructor)) coroutine_pool_init(void)
+void qemu_coroutine_enter(Coroutine *co, void *opaque)
 {
-    qemu_mutex_init(&pool_lock);
-}
+    Coroutine *self = qemu_coroutine_self();
+    CoroutineAction ret;
 
-static void __attribute__((destructor)) coroutine_pool_cleanup(void)
-{
-    Coroutine *co;
-    Coroutine *tmp;
+    trace_qemu_coroutine_enter(self, co, opaque);
 
-    QSLIST_FOREACH_SAFE(co, &pool, pool_next, tmp) {
-        QSLIST_REMOVE_HEAD(&pool, pool_next);
-        qemu_coroutine_delete(co);
+    if (co->caller) {
+        fprintf(stderr, "Co-routine re-entered recursively\n");
+        abort();
     }
 
-    qemu_mutex_destroy(&pool_lock);
-}
-
-static void coroutine_swap(Coroutine *from, Coroutine *to)
-{
-    CoroutineAction ret;
-
-    ret = qemu_coroutine_switch(from, to, COROUTINE_YIELD);
+    co->caller = self;
+    co->entry_arg = opaque;
+    ret = qemu_coroutine_switch(self, co, COROUTINE_ENTER);
 
-    qemu_co_queue_run_restart(to);
+    qemu_co_queue_run_restart(co);
 
     switch (ret) {
     case COROUTINE_YIELD:
         return;
     case COROUTINE_TERMINATE:
-        trace_qemu_coroutine_terminate(to);
-        coroutine_delete(to);
+        trace_qemu_coroutine_terminate(co);
+        coroutine_delete(co);
         return;
     default:
         abort();
     }
 }
 
-void qemu_coroutine_enter(Coroutine *co, void *opaque)
-{
-    Coroutine *self = qemu_coroutine_self();
-
-    trace_qemu_coroutine_enter(self, co, opaque);
-
-    if (co->caller) {
-        fprintf(stderr, "Co-routine re-entered recursively\n");
-        abort();
-    }
-
-    co->caller = self;
-    co->entry_arg = opaque;
-    coroutine_swap(self, co);
-}
-
 void coroutine_fn qemu_coroutine_yield(void)
 {
     Coroutine *self = qemu_coroutine_self();
@@ -135,5 +142,5 @@ void coroutine_fn qemu_coroutine_yield(void)
     }
 
     self->caller = NULL;
-    coroutine_swap(self, to);
+    qemu_coroutine_switch(self, to, COROUTINE_YIELD);
 }