libgo/runtime/mcache.c

   1 // Copyright 2009 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // Per-P malloc cache for small objects.
   6 //
   7 // See malloc.h for an overview.
   8
   9 #include "runtime.h"
  10 #include "arch.h"
  11 #include "malloc.h"
  12
  13 void
  14 runtime_MCache_Refill(MCache *c, int32 sizeclass)
  15 {
  16         MCacheList *l;
  17
  18         // Replenish using central lists.
  19         l = &c->list[sizeclass];
  20         if(l->list)
  21                 runtime_throw("MCache_Refill: the list is not empty");
  22         l->nlist = runtime_MCentral_AllocList(&runtime_mheap.central[sizeclass], &l->list);
  23         if(l->list == nil)
  24                 runtime_throw("out of memory");
  25 }
  26
  27 // Take n elements off l and return them to the central free list.
  28 static void
  29 ReleaseN(MCacheList *l, int32 n, int32 sizeclass)
  30 {
  31         MLink *first, **lp;
  32         int32 i;
  33
  34         // Cut off first n elements.
  35         first = l->list;
  36         lp = &l->list;
  37         for(i=0; i<n; i++)
  38                 lp = &(*lp)->next;
  39         l->list = *lp;
  40         *lp = nil;
  41         l->nlist -= n;
  42
  43         // Return them to central free list.
  44         runtime_MCentral_FreeList(&runtime_mheap.central[sizeclass], first);
  45 }
  46
  47 void
  48 runtime_MCache_Free(MCache *c, void *v, int32 sizeclass, uintptr size)
  49 {
  50         MCacheList *l;
  51         MLink *p;
  52
  53         // Put back on list.
  54         l = &c->list[sizeclass];
  55         p = v;
  56         p->next = l->list;
  57         l->list = p;
  58         l->nlist++;
  59         c->local_cachealloc -= size;
  60
  61         // We transfer span at a time from MCentral to MCache,
  62         // if we have 2 times more than that, release a half back.
  63         if(l->nlist >= 2*(runtime_class_to_allocnpages[sizeclass]<<PageShift)/size)
  64                 ReleaseN(l, l->nlist/2, sizeclass);
  65 }
  66
  67 void
  68 runtime_MCache_ReleaseAll(MCache *c)
  69 {
  70         int32 i;
  71         MCacheList *l;
  72
  73         for(i=0; i<NumSizeClasses; i++) {
  74                 l = &c->list[i];
  75                 if(l->list) {
  76                         runtime_MCentral_FreeList(&runtime_mheap.central[i], l->list);
  77                         l->list = nil;
  78                         l->nlist = 0;
  79                 }
  80         }
  81 }