Changeset 4156 in webkit for trunk/JavaScriptCore/kjs

Timestamp:

Apr 22, 2003, 5:09:32 PM (22 years ago)

Author:

mjs

Message:

Reviewed by Ken.

Improved List pool for 3% speed improvement on cvs-js-ibench

• kjs/list.cpp: Replaced the roving cursor with a free list and raised the high water mark to 384.

File:

• trunk/JavaScriptCore/kjs/list.cpp (modified) (5 diffs)

trunk/JavaScriptCore/kjs/list.cpp

@@ -29 +29 @@
 
 // tunable parameters
-const int poolSize = 32; // must be a power of 2
+const int poolSize = 384;
 const int inlineValuesSize = 4;
 
-// derived constants
-const int poolSizeMask = poolSize - 1;
 
 enum ListImpState { unusedInPool = 0, usedInPool, usedOnHeap, immortal };
@@ -44 +42 @@
     ValueImp **overflow;
 
+    ListImp *nextInFreeList;
+
 #if DUMP_STATISTICS
     int sizeHighWaterMark;
@@ -50 +50 @@
 
 static ListImp pool[poolSize];
-static int poolCursor;
+static ListImp *poolFreeList;
+static int poolUsed;
 
 #if DUMP_STATISTICS
@@ -89 +90 @@
 {
     // Find a free one in the pool.
-    int c = poolCursor;
-    int i = c;
-    do {
-        ListImp *imp = &pool[i];
-        ListImpState s = imp->state;
-        i = (i + 1) & poolSizeMask;
-        if (s == unusedInPool) {
-            poolCursor = i;
-            imp->state = usedInPool;
-            return imp;
-        }
-    } while (i != c);
+    if (poolUsed < poolSize) {
+        ListImp *imp = poolFreeList ? poolFreeList : &pool[0];
+        poolFreeList = imp->nextInFreeList ? imp->nextInFreeList : imp + 1;
+        imp->state = usedInPool;
+        poolUsed++;
+        return imp;
+    }
     
     ListImp *imp = new ListImp;
@@ -109 +105 @@
 static inline void deallocateListImp(ListImp *imp)
 {
-    if (imp->state == usedInPool)
+    if (imp->state == usedInPool) {
         imp->state = unusedInPool;
-    else
+        imp->nextInFreeList = poolFreeList;
+        poolFreeList = imp;
+        poolUsed--;
+    } else {
         delete imp;
+    }
 }