Changeset 41660 in webkit for trunk/JavaScriptCore/wtf/TCSystemAlloc.cpp

Timestamp:

Mar 12, 2009, 8:33:27 PM (16 years ago)

Author:

[email protected]

Message:

<rdar://problem/6548446> TCMalloc_SystemRelease should use madvise rather than re-mmaping span of pages

• wtf/FastMalloc.cpp:

(WTF::mergeDecommittedStates): If either of the spans has been released to the system, release the other
span as well so that the flag in the merged span is accurate.

• wtf/Platform.h:
• wtf/TCSystemAlloc.cpp: Track decommitted spans when using MADV_FREE_REUSABLE / MADV_FREE_REUSE.

(TCMalloc_SystemRelease): Use madvise with MADV_FREE_REUSABLE when it is available.
(TCMalloc_SystemCommit): Use madvise with MADV_FREE_REUSE when it is available.

• wtf/TCSystemAlloc.h:

File:

• trunk/JavaScriptCore/wtf/TCSystemAlloc.cpp (modified) (2 diffs)

trunk/JavaScriptCore/wtf/TCSystemAlloc.cpp

@@ -382 +382 @@
 }
 
+#if HAVE(MADV_FREE_REUSE)
+
 void TCMalloc_SystemRelease(void* start, size_t length)
 {
-#if HAVE(MADV_DONTNEED)
+    while (madvise(start, length, MADV_FREE_REUSABLE) == -1 && errno == EAGAIN) { }
+}
+
+#elif HAVE(MADV_DONTNEED)
+
+void TCMalloc_SystemRelease(void* start, size_t length)
+{
   if (FLAGS_malloc_devmem_start) {
     // It's not safe to use MADV_DONTNEED if we've been mapping
@@ -415 +423 @@
       // NOP
     }
-    return;
-  }
-#endif
-
-#if HAVE(MMAP)
+  }
+}
+
+#elif HAVE(MMAP)
+
+void TCMalloc_SystemRelease(void* start, size_t length)
+{
   void* newAddress = mmap(start, length, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
   // If the mmap failed then that's ok, we just won't return the memory to the system.
   ASSERT_UNUSED(newAddress, newAddress == start || newAddress == reinterpret_cast<void*>(MAP_FAILED));
-  return;
-#endif
-
-#if !HAVE(MADV_DONTNEED) && !HAVE(MMAP)
-  UNUSED_PARAM(start);
-  UNUSED_PARAM(length);
-#endif
-}
-
-#if HAVE(VIRTUALALLOC)
+}
+
+#else
+
+// Platforms that don't support returning memory use an empty inline version of TCMalloc_SystemRelease
+// declared in TCSystemAlloc.h
+
+#endif
+
+#if HAVE(MADV_FREE_REUSE)
+
+void TCMalloc_SystemCommit(void* start, size_t length)
+{
+    while (madvise(start, length, MADV_FREE_REUSE) == -1 && errno == EAGAIN) { }
+}
+
+#elif HAVE(VIRTUALALLOC)
+
 void TCMalloc_SystemCommit(void*, size_t)
 {
 }
-#endif
+
+#else
+
+// Platforms that don't need to explicitly commit memory use an empty inline version of TCMalloc_SystemCommit
+// declared in TCSystemAlloc.h
+
+#endif