Changeset 42842 in webkit for trunk/JavaScriptCore/interpreter/RegisterFile.h

Timestamp:

Apr 24, 2009, 2:53:46 PM (16 years ago)

Author:

[email protected]

Message:

<rdar://problem/6050421> JavaScript register file should remap to release physical pages accumulated during deep recursion

Reviewed by Geoff Garen

We now track the maximum extent of the RegisterFile, and when we reach the final
return from JS (so the stack portion of the registerfile becomes empty) we see
if that extent is greater than maxExcessCapacity. If it is we use madvise or
VirtualFree to release the physical pages that were backing the excess.

File:

• trunk/JavaScriptCore/interpreter/RegisterFile.h (modified) (6 diffs)

trunk/JavaScriptCore/interpreter/RegisterFile.h

@@ -115 +115 @@
         static const size_t defaultMaxGlobals = 8192;
         static const size_t commitSize = 1 << 14;
+        // Allow 8k of excess registers before we start trying to reap the registerfile
+        static const ptrdiff_t maxExcessCapacity = 8 * 1024;
 
         RegisterFile(size_t capacity = defaultCapacity, size_t maxGlobals = defaultMaxGlobals);
@@ -139 +141 @@
 
     private:
+        void releaseExcessCapacity();
         size_t m_numGlobals;
         const size_t m_maxGlobals;
@@ -145 +148 @@
         Register* m_max;
         Register* m_buffer;
+        Register* m_maxUsed;
+
 #if HAVE(VIRTUALALLOC)
         Register* m_commitEnd;
@@ -186 +191 @@
         m_start = m_buffer + maxGlobals;
         m_end = m_start;
+        m_maxUsed = m_end;
         m_max = m_start + capacity;
     }
@@ -193 +199 @@
         if (newEnd < m_end)
             m_end = newEnd;
+        if (m_end == m_start && (m_maxUsed - m_start) > maxExcessCapacity) 
+            releaseExcessCapacity();
     }
 
@@ -214 +222 @@
 #endif
 
+        if (newEnd > m_maxUsed)
+            m_maxUsed = newEnd;
+
         m_end = newEnd;
         return true;