[kaffe] gc patch

Helmer Krämer hkraemer@freenet.de
Thu Jun 12 01:18:01 2003


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Hi all,

I've attached a small patch to kaffe's gc and would like to
hear your opinions before commiting it.

On the one hand, it provides for a cleaner seperation between
heap management and garbage collection. Therefore, it moves any
logic how one could free some memory out of gc_heap_malloc into
gcMalloc. Second, gc_system_alloc is renamed to gc_heap_grow and
exported so that gcMalloc can call it.

On the other hand, it contains some bugfixes. The memory that's
allocated by the heap manager is no longer aligned at a hard coded
8 byte boundary, but rather at a ALIGNMENT_OF_SIZE(sizeof(jdouble))
boundary. Second, the initialization of a block in gc_small_block
was somewhat wrong (think that's what's causing the SIGBUS on
HPUX).

Comments?

Greetings,
Helmer
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Index: kaffe/kaffevm/mem/gc-incremental.c
===================================================================
RCS file: /cvs/kaffe/kaffe/kaffe/kaffevm/mem/gc-incremental.c,v
retrieving revision 1.62
diff -u -r1.62 gc-incremental.c
--- kaffe/kaffevm/mem/gc-incremental.c	11 Mar 2003 08:00:18 -0000	1.62
+++ kaffe/kaffevm/mem/gc-incremental.c	12 Jun 2003 07:58:15 -0000
@@ -860,19 +860,53 @@
 	int i;
 	size_t bsz;
 	int iLockRoot;
+	int times = 0;
 
 	assert(gc_init != 0);
 	assert(fidx < nrTypes && size != 0);
 
-	unit = gc_heap_malloc(size + sizeof(gc_unit));
-
-	/* keep pointer to object */
-	mem = UTOMEM(unit);
-	if (unit == 0) {
-		return 0;
-	}
+	size += sizeof(gc_unit);
 
 	lockStaticMutex(&gc_lock);
+
+	for (unit=0; unit==0;) {
+		times++;
+		unit = gc_heap_malloc(size);
+	
+		/* keep pointer to object */
+		mem = UTOMEM(unit);
+		if (unit == 0) {
+			switch (times) {
+			case 1:
+				/* Try invoking GC if it is available */
+				if (garbageman != 0) {
+					unlockStaticMutex(&gc_lock);
+					adviseGC();
+					lockStaticMutex(&gc_lock);
+				}
+				break;	  
+
+			case 2:
+				/* Grow the heap */
+				gc_heap_grow(size);
+				break;
+
+			default:
+				if (DBGEXPR(CATCHOUTOFMEM, true, false)) {
+					/*
+					 * If we ran out of memory, a OutOfMemoryException is
+					 * thrown.  If we fail to allocate memory for it, all
+					 * is lost.
+					 */
+					static int ranout;
+					assert (ranout++ == 0 || !!!"Ran out of memory!");
+				}
+				/* Guess we've really run out */
+				unlockStaticMutex(&gc_lock);
+				return (0);
+			}
+		}
+	}
 
 	info = GCMEM2BLOCK(mem);
 	i = GCMEM2IDX(info, unit);
Index: kaffe/kaffevm/mem/gc-mem.c
===================================================================
RCS file: /cvs/kaffe/kaffe/kaffe/kaffevm/mem/gc-mem.c,v
retrieving revision 1.43
diff -u -r1.43 gc-mem.c
--- kaffe/kaffevm/mem/gc-mem.c	2 Jun 2003 14:15:47 -0000	1.43
+++ kaffe/kaffevm/mem/gc-mem.c	12 Jun 2003 07:58:16 -0000
@@ -41,7 +41,6 @@
 
 static gc_block* gc_primitive_alloc(size_t);
 void gc_primitive_free(gc_block*);
-static void* gc_system_alloc(size_t);
 
 uintp gc_heap_base;
 uintp gc_block_base;
@@ -206,7 +205,7 @@
 	 * of powers of two
 	 */
 #define	OBJSIZE(NR) \
-	((gc_pgsize-GCBLOCK_OVH-ROUNDUPALIGN(1)-(NR*(2+sizeof(void*))))/NR)
+	((gc_pgsize-ROUNDUPALIGN(1)-(NR*(2+sizeof(void*))))/NR)
 
 	/* For a given number of tiles in a block, work out the size of
 	 * the allocatable units which'll fit in them and build a translation
@@ -280,11 +279,10 @@
 	gc_heap_initial_size = ROUNDUPPAGESIZE(gc_heap_initial_size);
 
 	/* allocate heap of initial size from system */
-	gc_system_alloc(gc_heap_initial_size);
+	gc_heap_grow(gc_heap_initial_size);
 }
 
-/*
- * gc_heap_malloc
+/**
  * Allocate a piece of memory.
  */
 void*
@@ -292,11 +290,10 @@
 {
 	static int gc_heap_init = 0;
 	size_t lnr;
-	gc_freeobj* mem;
+	gc_freeobj* mem = 0;
 	gc_block** mptr;
 	gc_block* blk;
 	size_t nsz;
-	int times;
 	int iLockRoot;
 
 	/* Initialise GC heap first time in - we must assume single threaded
@@ -309,8 +306,6 @@
 
 	lockStaticMutex(&gc_heap_lock);
 
-	times = 0;
-
 DBG(SLACKANAL,
 	if (GC_SMALL_OBJECT(sz)) {
 		totalslack += (freelist[sztable[sz].list].sz - sz);
@@ -318,9 +313,6 @@
 	}
     )
 
-	rerun:;
-	times++;
-
 DBG(GCDIAG, 
 	gc_heap_check();
     )
@@ -342,8 +334,7 @@
 		else {
 			blk = gc_small_block(nsz);
 			if (blk == 0) {
-				nsz = gc_pgsize;
-				goto nospace;
+				goto out;
 			}
 			blk->next = *mptr;
 			*mptr = blk;
@@ -378,9 +369,7 @@
 		nsz = sz;
 		blk = gc_large_block(nsz);
 		if (blk == 0) {
-			nsz = nsz + GCBLOCK_OVH + sizeof(gcFuncs*) + ROUNDUPALIGN(1);
-			nsz = ROUNDUPPAGESIZE(nsz);
-			goto nospace;
+			goto out;
 		}
 		mem = GCBLOCK2FREE(blk, 0);
 		GC_SET_STATE(blk, 0, GC_STATE_NORMAL);
@@ -395,60 +384,13 @@
 
 	assert(GC_OBJECT_SIZE(mem) >= sz);
 
+	out:
 	unlockStaticMutex(&gc_heap_lock);
 
 	return (mem);
-
-	/* --------------------------------------------------------------- */
-	nospace:;
-
-	/* Failed to find space in any freelists. Must try to get the
-	 * memory from somewhere.
-	 */
-
-	switch (times) {
-	case 1:
-		/* Try invoking GC if it is available */
-		if (garbageman != 0) {
-			/* The other caller of invokeGC,  Runtime.gc() can't 
-			 * give up this lock on its own, since it does not 
-			 * hold this lock.
-			 */
-			unlockStaticMutex(&gc_heap_lock);
-			adviseGC();
-			lockStaticMutex(&gc_heap_lock);
-		}
-		break;
-
-	case 2:
-		/* Get from the system */
-		if (nsz < gc_heap_allocation_size) {
-			nsz = gc_heap_allocation_size;
-		}
-		gc_system_alloc(nsz);
-		break;
-
-	default:
-		if (DBGEXPR(CATCHOUTOFMEM, true, false))
-		{
-			/*
-			 * If we ran out of memory, a OutOfMemoryException is
-			 * thrown.  If we fail to allocate memory for it, all
-			 * is lost.
-			 */
-			static int ranout;
-			assert (ranout++ == 0 || !!!"Ran out of memory!");
-		}
-		/* Guess we've really run out */
-		unlockStaticMutex(&gc_heap_lock);
-		return (0);
-	}
-
-	/* Try again */
-	goto rerun;
 }
 
-/*
+/**
  * Free a piece of memory.
  */
 void
@@ -523,7 +465,7 @@
 	}
 	else {
 		/* Calculate true size of block */
-		msz = info->size + GCBLOCK_OVH + ROUNDUPALIGN(1);
+		msz = info->size + ROUNDUPALIGN(1);
 		msz = ROUNDUPPAGESIZE(msz);
 		info->size = msz;
 		gc_primitive_free(info);
@@ -555,7 +497,7 @@
 	}
 
 	/* Calculate number of objects in this block */
-	nr = (gc_pgsize-GCBLOCK_OVH-ROUNDUPALIGN(1))/(sz+2);
+	nr = (gc_pgsize-ROUNDUPALIGN(1))/(sz+2);
 
 	/* Setup the meta-data for the block */
 	DBG(GCDIAG, info->magic = GC_MAGIC);
@@ -570,12 +512,14 @@
 	DBG(GCDIAG, memset(info->data, 0, sz * nr));
 
 	/* Build the objects into a free list */
-	for (i = nr-1; i >= 0; i--) {
+	for (i = nr-1; i-- > 0;) {
 		GCBLOCK2FREE(info, i)->next = GCBLOCK2FREE(info, i+1);
 		GC_SET_COLOUR(info, i, GC_COLOUR_FREE);
 		GC_SET_STATE(info, i, GC_STATE_NORMAL);
 	}
 	GCBLOCK2FREE(info, nr-1)->next = 0;
+	GC_SET_COLOUR(info, nr-1, GC_COLOUR_FREE);
+	GC_SET_STATE(info, nr-1, GC_STATE_NORMAL);
 	info->free = GCBLOCK2FREE(info, 0);
 DBG(SLACKANAL,
 	int slack = ((void *)info) 
@@ -596,7 +540,7 @@
 	size_t msz;
 
 	/* Add in management overhead */
-	msz = sz+GCBLOCK_OVH+2+ROUNDUPALIGN(1);
+	msz = sz+2+ROUNDUPALIGN(1);
 	/* Round size up to a number of pages */
 	msz = ROUNDUPPAGESIZE(msz);
 
@@ -1005,17 +949,33 @@
 	return GCMEM2BLOCK(heap_addr);
 }
 
-static
-void*
-gc_system_alloc(size_t sz)
+/**
+ * Grows the heap.
+ *
+ * @param sz minimum number of bytes to grow.
+ * @return 0 in case of an error, otherwise != 0
+ */
+void *
+gc_heap_grow(size_t sz)
 {
 	gc_block* blk;
 
+	if (GC_SMALL_OBJECT(sz)) {
+		sz = gc_pgsize;
+	} else {
+		sz = sz + 2 + ROUNDUPALIGN(1);
+		sz = ROUNDUPPAGESIZE(sz);
+	}
+
+	if (sz < gc_heap_allocation_size) {
+		sz = gc_heap_allocation_size;
+	}
+
 	assert(sz % gc_pgsize == 0);
 
 	if (gc_heap_total == gc_heap_limit) {
 		return (0);
-	} else 	if (gc_heap_total + sz > gc_heap_limit) {
+	} else if (gc_heap_total + sz > gc_heap_limit) {
 		/* take as much memory as we can */
 		sz = gc_heap_limit - gc_heap_total;
 		assert(sz % gc_pgsize == 0);
@@ -1026,13 +986,14 @@
 #endif
 
 	blk = gc_block_alloc(sz);
-	
-DBG(GCSYSALLOC,
-	dprintf("gc_system_alloc: %ld byte at %p\n", (long) sz, blk);		)
+
+	DBG(GCSYSALLOC,
+	    dprintf("gc_system_alloc: %ld byte at %p\n", (long) sz, blk); )
 
 	if (blk == 0) {
 		return (0);
 	}
+
 	gc_heap_total += sz;
 	assert(gc_heap_total <= gc_heap_limit);
 
Index: kaffe/kaffevm/mem/gc-mem.h
===================================================================
RCS file: /cvs/kaffe/kaffe/kaffe/kaffevm/mem/gc-mem.h,v
retrieving revision 1.15
diff -u -r1.15 gc-mem.h
--- kaffe/kaffevm/mem/gc-mem.h	2 Jun 2003 14:15:47 -0000	1.15
+++ kaffe/kaffevm/mem/gc-mem.h	12 Jun 2003 07:58:16 -0000
@@ -14,6 +14,12 @@
 #ifndef __gc_mem_h
 #define	__gc_mem_h
 
+#include "md.h"
+
+#if !defined(ALIGNMENT_OF_SIZE)
+#define ALIGNMENT_OF_SIZE(S)	(S)
+#endif
+
 #ifndef gc_pgsize
 extern size_t gc_pgsize;
 extern int gc_pgbits;
@@ -44,7 +50,7 @@
  * Alignment for gc_blocks
  *
  */
-#define	MEMALIGN		8
+#define	MEMALIGN		(ALIGNMENT_OF_SIZE(sizeof(jdouble)))
 
 /**
  * rounds @V up to the next MEMALIGN boundary. 
@@ -69,6 +75,8 @@
 extern void*	gc_heap_malloc(size_t);    
 extern void	gc_heap_free(void*);
 
+extern void*	gc_heap_grow(size_t);
+
 /**
  * Evaluates to the size of the object that contains address @M.
  *
@@ -154,14 +162,12 @@
  * Evaluates to the first usable address in gc_block @B.
  *
  */ 
-#define GCBLOCK2BASE(B)	(((char *)gc_heap_base)		\
-			 + gc_pgsize * ((B) - GC_BLOCKS))
-
+#define GCBLOCK2BASE(B)		(((char *)gc_heap_base) \
+					 + gc_pgsize * ((B) - GC_BLOCKS))
 
 /* This is OK, gc_prim_(alloc|free) never assume GCBLOCKEND is really
    a valid block */
 #define GCBLOCKEND(B)		((B) + (((B)->size+gc_pgsize-1)>>gc_pgbits))
-#define GCBLOCK_OVH		0
 
 #define ASSERT_ONBLOCK(OBJ, BLK) assert(GCMEM2BLOCK(OBJ) == BLK)
 

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