Merge remote-tracking branch 'kwolf/for-anthony' into staging

# By Paolo Bonzini (7) and others
# Via Kevin Wolf
* kwolf/for-anthony: (22 commits)
  pc: add compatibility machine types for 1.4
  blockdev: enable discard by default
  qemu-nbd: add --discard option
  blockdev: add discard suboption to -drive
  block: implement BDRV_O_UNMAP
  block: complete all IOs before .bdrv_truncate
  coroutine: trim down nesting level in perf_nesting test
  coroutine: move pooling to common code
  qemu-iotests: Test qcow2 image creation options
  qemu-iotests: Add qemu-img compare test
  qemu-img: Add compare subcommand
  qemu-img: Add "Quiet mode" option
  block: Add synchronous wrapper for bdrv_co_is_allocated_above
  block: refuse negative iops and bps values
  block: use Error in do_check_io_limits()
  qcow2: support compressed clusters in BlockFragInfo
  qemu-img: add compressed clusters to BlockFragInfo
  qemu-img: fix missing space in qemu-img check output
  qcow2: record fragmentation statistics during check
  qcow2: introduce check_refcounts_l1/l2() flags
  ...

1 files changed, 43 insertions, 2 deletions

diff --git a/qemu-coroutine.c b/qemu-coroutine.c
index 0f6e268..25a14c6 100644
--- a/qemu-coroutine.c
+++ b/qemu-coroutine.c
@@ -17,13 +17,54 @@
 #include "block/coroutine.h"
 #include "block/coroutine_int.h"
 
+enum {
+    /* Maximum free pool size prevents holding too many freed coroutines */
+    POOL_MAX_SIZE = 64,
+};
+
+/** Free list to speed up creation */
+static QSLIST_HEAD(, Coroutine) pool = QSLIST_HEAD_INITIALIZER(pool);
+static unsigned int pool_size;
+
 Coroutine *qemu_coroutine_create(CoroutineEntry *entry)
 {
-    Coroutine *co = qemu_coroutine_new();
+    Coroutine *co;
+
+    co = QSLIST_FIRST(&pool);
+    if (co) {
+        QSLIST_REMOVE_HEAD(&pool, pool_next);
+        pool_size--;
+    } else {
+        co = qemu_coroutine_new();
+    }
+
     co->entry = entry;
     return co;
 }
 
+static void coroutine_delete(Coroutine *co)
+{
+    if (pool_size < POOL_MAX_SIZE) {
+        QSLIST_INSERT_HEAD(&pool, co, pool_next);
+        co->caller = NULL;
+        pool_size++;
+        return;
+    }
+
+    qemu_coroutine_delete(co);
+}
+
+static void __attribute__((destructor)) coroutine_cleanup(void)
+{
+    Coroutine *co;
+    Coroutine *tmp;
+
+    QSLIST_FOREACH_SAFE(co, &pool, pool_next, tmp) {
+        QSLIST_REMOVE_HEAD(&pool, pool_next);
+        qemu_coroutine_delete(co);
+    }
+}
+
 static void coroutine_swap(Coroutine *from, Coroutine *to)
 {
     CoroutineAction ret;
@@ -35,7 +76,7 @@ static void coroutine_swap(Coroutine *from, Coroutine *to)
         return;
     case COROUTINE_TERMINATE:
         trace_qemu_coroutine_terminate(to);
-        qemu_coroutine_delete(to);
+        coroutine_delete(to);
         return;
     default:
         abort();