[pypy-commit] stmgc default: Only acquire the mutex_pages_lock if there are really objects to free

[arigo]

Author: Armin Rigo <arigo at tunes.org>
Branch: 
Changeset: r885:39c5f170d4d1
Date: 2014-02-26 23:45 +0100
http://bitbucket.org/pypy/stmgc/changeset/39c5f170d4d1/

Log:	Only acquire the mutex_pages_lock if there are really objects to
	free

diff --git a/c7/stm/nursery.c b/c7/stm/nursery.c
--- a/c7/stm/nursery.c
+++ b/c7/stm/nursery.c
@@ -209,15 +209,20 @@
 
     /* free any object left from 'young_outside_nursery' */
     if (!tree_is_cleared(STM_PSEGMENT->young_outside_nursery)) {
-        mutex_pages_lock();
-
+        bool locked = false;
         wlog_t *item;
         TREE_LOOP_FORWARD(*STM_PSEGMENT->young_outside_nursery, item) {
+            if (!locked) {
+                mutex_pages_lock();
+                locked = true;
+            }
             _stm_large_free(stm_object_pages + item->addr);
         } TREE_LOOP_END;
 
+        if (locked)
+            mutex_pages_unlock();
+
         tree_clear(STM_PSEGMENT->young_outside_nursery);
-        mutex_pages_unlock();
     }
 }