code review 5279048: runtime: faster and more scalable GC

src/pkg/runtime/mcache.c

 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 // Per-thread (in Go, per-M) malloc cache for small objects.
 //
 // See malloc.h for an overview.
 
 #include "runtime.h"
 #include "arch_GOARCH.h"
@@ skipping 25 matching lines @@
                 l->nlistmin = l->nlist;
         c->size -= size;
 
         // v is zeroed except for the link pointer
         // that we used above; zero that.
         v->next = nil;
         if(zeroed) {
                 // block is zeroed iff second word is zero ...
                 if(size > sizeof(uintptr) && ((uintptr*)v)[1] != 0)
                         runtime·memclr((byte*)v, size);
-                else {
-                        // ... except for the link pointer
-                        // that we used above; zero that.
-                        v->next = nil;
-                }
         }
         c->local_cachealloc += size;
         c->local_objects++;
         return v;
 }
 
 // Take n elements off l and return them to the central free list.
 static void
 ReleaseN(MCache *c, MCacheList *l, int32 n, int32 sizeclass)
 {
@@ skipping 64 matching lines @@
 {
         int32 i;
         MCacheList *l;
 
         for(i=0; i<NumSizeClasses; i++) {
                 l = &c->list[i];
                 ReleaseN(c, l, l->nlist, i);
                 l->nlistmin = 0;
         }
 }