insert full blocks back at the end of the free list to hopefully reduce the...

insert full blocks back at the end of the free list to hopefully reduce the amount of times we have to check them

src/gc/heap.cpp

@@ -115,8 +115,6 @@ void* Heap::allocLarge(size_t size) {
 }
 
 static Block* alloc_block(uint64_t size, Block** prev) {
-    // TODO use mmap
-
     Block* rtn = (Block*)small_arena.doMmap(sizeof(Block));
     assert(rtn);
     rtn->size = size;
@@ -379,12 +377,11 @@ void* Heap::getAllocationFromInteriorPointer(void* ptr) {
     return &b->atoms[atom_idx];
 }
 
-static long freeChain(Block* head) {
-    long bytes_freed = 0;
-    while (head) {
-        int num_objects = head->numObjects();
-        int first_obj = head->minObjIndex();
-        int atoms_per_obj = head->atomsPerObj();
+static Block** freeChain(Block** head) {
+    while (Block* b = *head) {
+        int num_objects = b->numObjects();
+        int first_obj = b->minObjIndex();
+        int atoms_per_obj = b->atomsPerObj();
 
         for (int obj_idx = first_obj; obj_idx < num_objects; obj_idx++) {
             int atom_idx = obj_idx * atoms_per_obj;
@@ -392,10 +389,10 @@ static long freeChain(Block* head) {
             int bitmap_bit = atom_idx % 64;
             uint64_t mask = 1L << bitmap_bit;
 
-            if (head->isfree[bitmap_idx] & mask)
+            if (b->isfree[bitmap_idx] & mask)
                 continue;
 
-            void* p = &head->atoms[atom_idx];
+            void* p = &b->atoms[atom_idx];
             GCObjectHeader* header = headerFromObject(p);
 
             if (isMarked(header)) {
@@ -404,32 +401,29 @@ static long freeChain(Block* head) {
                 if (VERBOSITY() >= 2)
                     printf("Freeing %p\n", p);
                 // assert(p != (void*)0x127000d960); // the main module
-                bytes_freed += head->size;
-                head->isfree[bitmap_idx] |= mask;
+                b->isfree[bitmap_idx] |= mask;
             }
         }
 
-        head = head->next;
+        head = &b->next;
     }
-    return bytes_freed;
+    return head;
 }
 
 void Heap::freeUnmarked() {
-    long bytes_freed = 0;
     for (int bidx = 0; bidx < NUM_BUCKETS; bidx++) {
-        bytes_freed += freeChain(heads[bidx]);
-        bytes_freed += freeChain(full_heads[bidx]);
+        Block** chain_end = freeChain(&heads[bidx]);
+        freeChain(&full_heads[bidx]);
 
         while (Block* b = full_heads[bidx]) {
-            // these should be added at the end...
             removeFromLL(b);
-            insertIntoLL(&heads[bidx], b);
+            insertIntoLL(chain_end, b);
         }
     }
 
-    thread_caches.forEachValue([&bytes_freed](ThreadBlockCache* cache) {
+    thread_caches.forEachValue([](ThreadBlockCache* cache) {
         for (int bidx = 0; bidx < NUM_BUCKETS; bidx++) {
-            bytes_freed += freeChain(cache->cache_heads[bidx]);
+            freeChain(&cache->cache_heads[bidx]);
         }
     });
 
@@ -442,7 +436,6 @@ void Heap::freeUnmarked() {
         } else {
             if (VERBOSITY() >= 2)
                 printf("Freeing %p\n", p);
-            bytes_freed += cur->mmap_size();
 
             *cur->prev = cur->next;
             if (cur->next)
@@ -456,10 +449,6 @@ void Heap::freeUnmarked() {
 
         cur = cur->next;
     }
-
-    if (VERBOSITY("gc") >= 2)
-        if (bytes_freed)
-            printf("Freed %ld bytes\n", bytes_freed);
-}
-}
 }
+} // namespace gc
+} // namespace pyston