#include "Storage.h"
#include "RtsUtils.h"
#include "BlockAlloc.h"
+#include "OSMem.h"
#include <string.h>
static void initMBlock(void *mblock);
-// The free_list is kept sorted by size, smallest first.
-// In THREADED_RTS mode, the free list is protected by sm_mutex.
-
/* -----------------------------------------------------------------------------
Implementation notes
--------------------------------------------------------------------------- */
+/* ---------------------------------------------------------------------------
+ WATCH OUT FOR OVERFLOW
+
+ Be very careful with integer overflow here. If you have an
+ expression like (n_blocks * BLOCK_SIZE), and n_blocks is an int or
+ a nat, then it will very likely overflow on a 64-bit platform.
+ Always cast to StgWord (or W_ for short) first: ((W_)n_blocks * BLOCK_SIZE).
+
+ --------------------------------------------------------------------------- */
+
#define MAX_FREE_LIST 9
+// In THREADED_RTS mode, the free list is protected by sm_mutex.
+
static bdescr *free_list[MAX_FREE_LIST];
static bdescr *free_mblock_list;
if (best)
{
// we take our chunk off the end here.
- nat best_mblocks = BLOCKS_TO_MBLOCKS(best->blocks);
+ StgWord best_mblocks = BLOCKS_TO_MBLOCKS(best->blocks);
bd = FIRST_BDESCR((StgWord8*)MBLOCK_ROUND_DOWN(best) +
(best_mblocks-mblocks)*MBLOCK_SIZE);
if (ln == MAX_FREE_LIST) {
#if 0
- if ((mblocks_allocated * MBLOCK_SIZE_W - n_alloc_blocks * BLOCK_SIZE_W) > (1024*1024)/sizeof(W_)) {
+ if (((W_)mblocks_allocated * MBLOCK_SIZE_W - (W_)n_alloc_blocks * BLOCK_SIZE_W) > (1024*1024)/sizeof(W_)) {
debugBelch("Fragmentation, wanted %d blocks:", n);
RtsFlags.DebugFlags.block_alloc = 1;
checkFreeListSanity();
p->gen = NULL;
p->gen_no = 0;
/* fill the block group with garbage if sanity checking is on */
- IF_DEBUG(sanity,memset(p->start, 0xaa, p->blocks * BLOCK_SIZE));
+ IF_DEBUG(sanity,memset(p->start, 0xaa, (W_)p->blocks * BLOCK_SIZE));
if (p->blocks == 0) barf("freeGroup: block size is zero");
low_mblocks = 1 + (blocks - BLOCKS_PER_MBLOCK) / (MBLOCK_SIZE / BLOCK_SIZE);
high_mblocks = (bd->blocks - blocks) / (MBLOCK_SIZE / BLOCK_SIZE);
- new_mblock = (void *) ((P_)MBLOCK_ROUND_DOWN(bd) + low_mblocks * MBLOCK_SIZE_W);
+ new_mblock = (void *) ((P_)MBLOCK_ROUND_DOWN(bd) + (W_)low_mblocks * MBLOCK_SIZE_W);
initMBlock(new_mblock);
new_bd = FIRST_BDESCR(new_mblock);
new_bd->blocks = MBLOCK_GROUP_BLOCKS(high_mblocks);
return n;
}
+void returnMemoryToOS(nat n /* megablocks */)
+{
+ static bdescr *bd;
+ nat size;
+
+ bd = free_mblock_list;
+ while ((n > 0) && (bd != NULL)) {
+ size = BLOCKS_TO_MBLOCKS(bd->blocks);
+ if (size > n) {
+ nat newSize = size - n;
+ char *freeAddr = MBLOCK_ROUND_DOWN(bd->start);
+ freeAddr += newSize * MBLOCK_SIZE;
+ bd->blocks = MBLOCK_GROUP_BLOCKS(newSize);
+ freeMBlocks(freeAddr, n);
+ n = 0;
+ }
+ else {
+ char *freeAddr = MBLOCK_ROUND_DOWN(bd->start);
+ n -= size;
+ bd = bd->link;
+ freeMBlocks(freeAddr, size);
+ }
+ }
+ free_mblock_list = bd;
+
+ IF_DEBUG(gc,
+ if (n != 0) {
+ debugBelch("Wanted to free %d more MBlocks than are freeable\n",
+ n);
+ }
+ );
+}
+
/* -----------------------------------------------------------------------------
Debugging
-------------------------------------------------------------------------- */