merge upstream HEAD

[ghc-hetmet.git] / rts / sm / BlockAlloc.c

diff --git a/rts/sm/BlockAlloc.c b/rts/sm/BlockAlloc.c
index ba9220a..0b8955c 100644 (file)
--- a/rts/sm/BlockAlloc.c
+++ b/rts/sm/BlockAlloc.c
@@ -21,6 +21,7 @@
 #include "Storage.h"
 #include "RtsUtils.h"
 #include "BlockAlloc.h"
+#include "OSMem.h"
 
 #include <string.h>
 
@@ -331,9 +332,7 @@ allocGroup (nat n)
         bd = alloc_mega_group(mblocks);
         // only the bdescrs of the first MB are required to be initialised
         initGroup(bd);
-
-        IF_DEBUG(sanity, checkFreeListSanity());
-        return bd;
+        goto finish;
     }
     
     n_alloc_blocks += n;
@@ -346,8 +345,9 @@ allocGroup (nat n)
     }
 
     if (ln == MAX_FREE_LIST) {
-#if 0
-        if (((W_)mblocks_allocated * MBLOCK_SIZE_W - (W_)n_alloc_blocks * BLOCK_SIZE_W) > (1024*1024)/sizeof(W_)) {
+#if 0  /* useful for debugging fragmentation */
+        if ((W_)mblocks_allocated * BLOCKS_PER_MBLOCK * BLOCK_SIZE_W
+             - (W_)((n_alloc_blocks - n) * BLOCK_SIZE_W) > (2*1024*1024)/sizeof(W_)) {
             debugBelch("Fragmentation, wanted %d blocks:", n);
             RtsFlags.DebugFlags.block_alloc = 1;
             checkFreeListSanity();
@@ -362,8 +362,7 @@ allocGroup (nat n)
         initGroup(rem); // init the slop
         n_alloc_blocks += rem->blocks;
         freeGroup(rem);                 // add the slop on to the free list
-        IF_DEBUG(sanity, checkFreeListSanity());
-        return bd;
+        goto finish;
     }
 
     bd = free_list[ln];
@@ -371,18 +370,22 @@ allocGroup (nat n)
     if (bd->blocks == n)               // exactly the right size!
     {
         dbl_link_remove(bd, &free_list[ln]);
+        initGroup(bd);
     }
     else if (bd->blocks >  n)            // block too big...
     {                              
         bd = split_free_block(bd, n, ln);
+        ASSERT(bd->blocks == n);
+        initGroup(bd);
     }
     else
     {
         barf("allocGroup: free list corrupted");
     }
-    initGroup(bd);             // initialise it
+
+finish:
+    IF_DEBUG(sanity, memset(bd->start, 0xaa, bd->blocks * BLOCK_SIZE));
     IF_DEBUG(sanity, checkFreeListSanity());
-    ASSERT(bd->blocks == n);
     return bd;
 }
 
@@ -575,48 +578,6 @@ freeChain_lock(bdescr *bd)
     RELEASE_SM_LOCK;
 }
 
-// splitBlockGroup(bd,B) splits bd in two.  Afterward, bd will have B
-// blocks, and a new block descriptor pointing to the remainder is
-// returned.
-bdescr *
-splitBlockGroup (bdescr *bd, nat blocks)
-{
-    bdescr *new_bd;
-
-    if (bd->blocks <= blocks) {
-        barf("splitLargeBlock: too small");
-    }
-
-    if (bd->blocks > BLOCKS_PER_MBLOCK) {
-        nat low_mblocks, high_mblocks;
-        void *new_mblock;
-        if ((blocks - BLOCKS_PER_MBLOCK) % (MBLOCK_SIZE / BLOCK_SIZE) != 0) {
-            barf("splitLargeBlock: not a multiple of a megablock");
-        }
-        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) + (W_)low_mblocks * MBLOCK_SIZE_W);
-        initMBlock(new_mblock);
-        new_bd = FIRST_BDESCR(new_mblock);
-        new_bd->blocks = MBLOCK_GROUP_BLOCKS(high_mblocks);
-
-        ASSERT(blocks + new_bd->blocks == 
-               bd->blocks + BLOCKS_PER_MBLOCK - MBLOCK_SIZE/BLOCK_SIZE);
-    }
-    else
-    {
-        // NB. we're not updating all the bdescrs in the split groups to
-        // point to the new heads, so this can only be used for large
-        // objects which do not start in the non-head block.
-        new_bd = bd + blocks;
-        new_bd->blocks = bd->blocks - blocks;
-    }
-    bd->blocks = blocks;
-
-    return new_bd;
-}
-
 static void
 initMBlock(void *mblock)
 {
@@ -671,6 +632,41 @@ countAllocdBlocks(bdescr *bd)
     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;
+
+    osReleaseFreeMemory();
+
+    IF_DEBUG(gc,
+        if (n != 0) {
+            debugBelch("Wanted to free %d more MBlocks than are freeable\n",
+                       n);
+        }
+    );
+}
+
 /* -----------------------------------------------------------------------------
    Debugging
    -------------------------------------------------------------------------- */