Changeset 45566 in webkit

Timestamp:

Jul 6, 2009 2:13:59 PM (15 years ago)

Author:

adachan@apple.com

Message:

Reviewed by Darin Adler and Mark Rowe.

Decommitted spans are added to the list of normal spans rather than
the returned spans in TCMalloc_PageHeap::Delete().
​https://bugs.webkit.org/show_bug.cgi?id=26998

In TCMalloc_PageHeap::Delete(), the deleted span can be decommitted in
the process of merging with neighboring spans that are also decommitted.
The merged span needs to be placed in the list of returned spans (spans
whose memory has been returned to the system). Right now it's always added
to the list of the normal spans which can theoretically cause thrashing.

• wtf/FastMalloc.cpp: (WTF::TCMalloc_PageHeap::Delete):

Location:

trunk/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• wtf/FastMalloc.cpp (modified) (2 diffs)

trunk/JavaScriptCore/ChangeLog

@@ +1 @@
+2009-07-06  Ada Chan  <adachan@apple.com>
+
+        Reviewed by Darin Adler and Mark Rowe.
+
+        Decommitted spans are added to the list of normal spans rather than 
+        the returned spans in TCMalloc_PageHeap::Delete().
+        https://bugs.webkit.org/show_bug.cgi?id=26998
+        
+        In TCMalloc_PageHeap::Delete(), the deleted span can be decommitted in 
+        the process of merging with neighboring spans that are also decommitted.  
+        The merged span needs to be placed in the list of returned spans (spans 
+        whose memory has been returned to the system).  Right now it's always added 
+        to the list of the normal spans which can theoretically cause thrashing.  
+
+        * wtf/FastMalloc.cpp:
+        (WTF::TCMalloc_PageHeap::Delete):
+
 2009-07-05  Lars Knoll  <lars.knoll@nokia.com>
 

trunk/JavaScriptCore/wtf/FastMalloc.cpp

@@ -1527 +1527 @@
   // entries for the pieces we are merging together because we only
   // care about the pagemap entries for the boundaries.
-  //
-  // Note that the spans we merge into "span" may come out of
-  // a "returned" list.  For simplicity, we move these into the
-  // "normal" list of the appropriate size class.
   const PageID p = span->start;
   const Length n = span->length;
@@ -1561 +1557 @@
   Event(span, 'D', span->length);
   span->free = 1;
-  if (span->length < kMaxPages) {
-    DLL_Prepend(&free_[span->length].normal, span);
-  } else {
-    DLL_Prepend(&large_.normal, span);
+#if TCMALLOC_TRACK_DECOMMITED_SPANS
+  if (span->decommitted) {
+    if (span->length < kMaxPages)
+      DLL_Prepend(&free_[span->length].returned, span);
+    else
+      DLL_Prepend(&large_.returned, span);
+  } else
+#endif
+  {
+    if (span->length < kMaxPages)
+      DLL_Prepend(&free_[span->length].normal, span);
+    else
+      DLL_Prepend(&large_.normal, span);
   }
   free_pages_ += n;