From: Jong Hyuk Choi <jongchoi@openldap.org>
Date: Tue, 23 Nov 2004 15:37:06 +0000 (+0000)
Subject: buddy allocator for sl_malloc. Configurable at thread heap creation time. Need optimi... 
X-Git-Tag: OPENLDAP_REL_ENG_2_3_0ALPHA~242
X-Git-Url: https://git.sur5r.net/?a=commitdiff_plain;h=994edd550049ace8d87f39652dfa438d9f19dcab;p=openldap

buddy allocator for sl_malloc. Configurable at thread heap creation time. Need optimization for higher perf.
---

diff --git a/servers/slapd/sl_malloc.c b/servers/slapd/sl_malloc.c
index 923e44462b..ec8393a8a7 100644
--- a/servers/slapd/sl_malloc.c
+++ b/servers/slapd/sl_malloc.c
@@ -21,11 +21,7 @@
 
 #include "slap.h"
 
-struct slab_heap {
-	void *h_base;
-	void *h_last;
-	void *h_end;
-};
+static void print_slheap(int level, void *ctx);
 
 void
 slap_sl_mem_destroy(
@@ -34,9 +30,48 @@ slap_sl_mem_destroy(
 )
 {
 	struct slab_heap *sh = data;
+	int pad = 2*sizeof(int)-1, pad_shift;
+	int order_start = -1, i;
+	struct slab_object *so;
 
-	ber_memfree_x(sh->h_base, NULL);
-	ber_memfree_x(sh, NULL);
+	if (sh->sh_stack) {
+		ber_memfree_x(sh->sh_base, NULL);
+		ber_memfree_x(sh, NULL);
+	} else {
+		pad_shift = pad - 1;
+		do {
+			order_start++;
+		} while (pad_shift >>= 1);
+
+		for (i = 0; i <= sh->sh_maxorder - order_start; i++) {
+			so = LDAP_LIST_FIRST(&sh->sh_free[i]);
+			while (so) {
+				struct slab_object *so_tmp = so;
+				so = LDAP_LIST_NEXT(so, so_link);
+				LDAP_LIST_INSERT_HEAD(&sh->sh_sopool, so_tmp, so_link);
+			}
+			ch_free(sh->sh_map[i]);
+		}
+		ch_free(sh->sh_free);
+		ch_free(sh->sh_map);
+
+		so = LDAP_LIST_FIRST(&sh->sh_sopool);
+		while (so) {
+			struct slab_object *so_tmp = so;
+			so = LDAP_LIST_NEXT(so, so_link);
+			if (!so_tmp->so_blockhead) {
+				LDAP_LIST_REMOVE(so_tmp, so_link);
+			}
+		}
+		so = LDAP_LIST_FIRST(&sh->sh_sopool);
+		while (so) {
+			struct slab_object *so_tmp = so;
+			so = LDAP_LIST_NEXT(so, so_link);
+			ch_free(so_tmp);
+		}
+		ber_memfree_x(sh->sh_base, NULL);
+		ber_memfree_x(sh, NULL);
+	}
 }
 
 BerMemoryFunctions slap_sl_mfuncs =
@@ -55,37 +90,140 @@ static struct slab_heap *slheap;
 void *
 slap_sl_mem_create(
 	ber_len_t size,
+	int stack,
 	void *ctx
 )
 {
 	struct slab_heap *sh = NULL;
-	int pad = 2*sizeof(int)-1;
+	ber_len_t size_shift;
+	int pad = 2*sizeof(int)-1, pad_shift;
+	int order = -1, order_start = -1, order_end = -1;
+	int i, k;
+	struct slab_object *so, *so_block;
 
 #ifdef NO_THREADS
 	sh = slheap;
 #else
-	ldap_pvt_thread_pool_getkey( ctx, (void *)slap_sl_mem_init, (void **)&sh, NULL );
+	ldap_pvt_thread_pool_getkey(
+		ctx, (void *)slap_sl_mem_init, (void **)&sh, NULL );
 #endif
 
 	/* round up to doubleword boundary */
 	size += pad;
 	size &= ~pad;
 
-	if (!sh) {
-		sh = ch_malloc( sizeof(struct slab_heap) );
-		sh->h_base = ch_malloc( size );
+	if (stack) {
+		if (!sh) {
+			sh = ch_malloc(sizeof(struct slab_heap));
+			sh->sh_base = ch_malloc(size);
+#ifdef NO_THREADS
+			slheap = sh;
+#else
+			ldap_pvt_thread_pool_setkey(ctx, (void *)slap_sl_mem_init,
+				(void *)sh, slap_sl_mem_destroy);
+#endif
+		} else if ( size > (char *)sh->sh_end - (char *)sh->sh_base ) {
+			sh->sh_base = ch_realloc(sh->sh_base, size);
+		}
+		sh->sh_last = sh->sh_base;
+		sh->sh_end = (char *) sh->sh_base + size;
+		sh->sh_stack = stack;
+		return sh;
+	} else {
+		size_shift = size - 1;
+		do {
+			order_end++;
+		} while (size_shift >>= 1);
+
+		pad_shift = pad - 1;
+		do {
+			order_start++;
+		} while (pad_shift >>= 1);
+
+		order = order_end - order_start + 1;
+
+		if (!sh) {
+			sh = (struct slab_heap *) ch_malloc(sizeof(struct slab_heap));
+			sh->sh_base = ch_malloc(size);
 #ifdef NO_THREADS
-		slheap = sh;
+			slheap = sh;
 #else
-		ldap_pvt_thread_pool_setkey( ctx, (void *)slap_sl_mem_init,
-			(void *)sh, slap_sl_mem_destroy );
+			ldap_pvt_thread_pool_setkey(ctx, (void *)slap_sl_mem_init,
+				(void *)sh, slap_sl_mem_destroy);
 #endif
-	} else if ( size > (char *) sh->h_end - (char *) sh->h_base ) {
-		sh->h_base = ch_realloc( sh->h_base, size );
+		} else {
+			for (i = 0; i <= sh->sh_maxorder - order_start; i++) {
+				so = LDAP_LIST_FIRST(&sh->sh_free[i]);
+				while (so) {
+					struct slab_object *so_tmp = so;
+					so = LDAP_LIST_NEXT(so, so_link);
+					LDAP_LIST_INSERT_HEAD(&sh->sh_sopool, so_tmp, so_link);
+				}
+				ch_free(sh->sh_map[i]);
+			}
+			ch_free(sh->sh_free);
+			ch_free(sh->sh_map);
+
+			so = LDAP_LIST_FIRST(&sh->sh_sopool);
+			while (so) {
+				struct slab_object *so_tmp = so;
+				so = LDAP_LIST_NEXT(so, so_link);
+				if (!so_tmp->so_blockhead) {
+					LDAP_LIST_REMOVE(so_tmp, so_link);
+				}
+			}
+			so = LDAP_LIST_FIRST(&sh->sh_sopool);
+			while (so) {
+				struct slab_object *so_tmp = so;
+				so = LDAP_LIST_NEXT(so, so_link);
+				ch_free(so_tmp);
+			}
+
+			if (size > (char *)sh->sh_end - (char *)sh->sh_base) {
+				sh->sh_base = realloc(sh->sh_base, size);
+			}
+		}
+		sh->sh_end = (char *)sh->sh_base + size;
+		sh->sh_maxorder = order_end;
+
+		sh->sh_free = (struct sh_freelist *)
+						ch_malloc(order * sizeof(struct sh_freelist));
+		for (i = 0; i < order; i++) {
+			LDAP_LIST_INIT(&sh->sh_free[i]);
+		}
+
+		LDAP_LIST_INIT(&sh->sh_sopool);
+
+		if (LDAP_LIST_EMPTY(&sh->sh_sopool)) {
+			so_block = (struct slab_object *)ch_malloc(
+							SLAP_SLAB_SOBLOCK * sizeof( struct slab_object));
+			so_block[0].so_blockhead = 1;
+			LDAP_LIST_INSERT_HEAD(&sh->sh_sopool, &so_block[0], so_link);
+			for (k = 1; k < SLAP_SLAB_SOBLOCK; k++) {
+				so_block[k].so_blockhead = 0;
+				LDAP_LIST_INSERT_HEAD(&sh->sh_sopool, &so_block[k], so_link);
+			}
+			so = LDAP_LIST_FIRST(&sh->sh_sopool);
+			LDAP_LIST_REMOVE(so, so_link);
+			so->so_ptr = sh->sh_base;
+		} else {
+			so = LDAP_LIST_FIRST(&sh->sh_sopool);
+			LDAP_LIST_REMOVE(so, so_link);
+			so->so_ptr = sh->sh_base;
+		}
+
+		LDAP_LIST_INSERT_HEAD(&sh->sh_free[order-1], so, so_link);
+
+		sh->sh_map = (unsigned char **)
+					ch_malloc(order * sizeof(unsigned long *));
+		for (i = 0; i < order; i++) {
+			sh->sh_map[i] = (unsigned char *)
+							ch_malloc(size >> (1 << (order_start + i + 3)));
+			memset(sh->sh_map[i], 0, size >> (1 << (order_start + i + 3)));
+		}
+		sh->sh_stack = stack;
+		return sh;
 	}
-	sh->h_last = sh->h_base;
-	sh->h_end = (char *) sh->h_base + size;
-	return sh;
 }
 
 void
@@ -109,27 +247,106 @@ slap_sl_malloc(
 )
 {
 	struct slab_heap *sh = ctx;
-	int pad = 2*sizeof(int)-1;
-	ber_len_t *new;
+	int size_shift;
+	int pad = 2*sizeof(int)-1, pad_shift;
+	int order = -1, order_start = -1;
+	struct slab_object *so_new, *so_left, *so_right, *so_block;
+	ber_len_t *ptr, *new;
+	unsigned long diff;
+	int i, j, k;
 
 	/* ber_set_option calls us like this */
-	if (!ctx) return ber_memalloc_x( size, NULL );
+	if (!ctx) return ber_memalloc_x(size, NULL);
+
+	Debug(LDAP_DEBUG_ANY, "slap_sl_malloc (%d)\n", size, 0, 0);
 
 	/* round up to doubleword boundary */
-	size += pad + sizeof( ber_len_t );
+	size += pad + sizeof(ber_len_t);
 	size &= ~pad;
 
-	if ((char *) sh->h_last + size >= (char *) sh->h_end ) {
-		Debug( LDAP_DEBUG_TRACE,
-			"slap_sl_malloc of %lu bytes failed, using ch_malloc\n",
-			(long)size, 0,0 );
-		return ch_malloc( size );
+	if (sh->sh_stack) {
+		if ((char *)sh->sh_last + size >= (char *)sh->sh_end) {
+			Debug(LDAP_DEBUG_TRACE,
+				"slap_sl_malloc of %lu bytes failed, using ch_malloc\n",
+				(long)size, 0, 0);
+			return ch_malloc(size);
+		}
+		new = sh->sh_last;
+		*new++ = size - sizeof(ber_len_t);
+		sh->sh_last = (char *) sh->sh_last + size;
+		return( (void *)new );
+	} else {
+		size_shift = size - 1;
+		do {
+			order++;
+		} while (size_shift >>= 1);
+
+		pad_shift = pad - 1;
+		do {
+			order_start++;
+		} while (pad_shift >>= 1);
+
+		for (i = order; i <= sh->sh_maxorder &&
+				LDAP_LIST_EMPTY(&sh->sh_free[i-order_start]); i++);
+
+		if (i == order) {
+			so_new = LDAP_LIST_FIRST(&sh->sh_free[i-order_start]);
+			LDAP_LIST_REMOVE(so_new, so_link);
+			ptr = so_new->so_ptr;
+			diff = (unsigned long)((char*)ptr -
+					(char*)sh->sh_base) >> (order + 1);
+			sh->sh_map[order-order_start][diff>>3] |= (1 << (diff & 0x7));
+			*ptr++ = size - sizeof(ber_len_t);
+			LDAP_LIST_INSERT_HEAD(&sh->sh_sopool, so_new, so_link);
+			return((void*)ptr);
+		} else if (i <= sh->sh_maxorder) {
+			for (j = i; j > order; j--) {
+				so_left = LDAP_LIST_FIRST(&sh->sh_free[j-order_start]);
+				LDAP_LIST_REMOVE(so_left, so_link);
+				if (LDAP_LIST_EMPTY(&sh->sh_sopool)) {
+					so_block = (struct slab_object *)ch_malloc(
+								SLAP_SLAB_SOBLOCK * sizeof(struct slab_object));
+					so_block[0].so_blockhead = 1;
+					LDAP_LIST_INSERT_HEAD(
+							&sh->sh_sopool, &so_block[0], so_link);
+					for (k = 1; k < SLAP_SLAB_SOBLOCK; k++) {
+						so_block[k].so_blockhead = 0;
+						LDAP_LIST_INSERT_HEAD(
+							&sh->sh_sopool, &so_block[k], so_link);
+					}
+					so_right = LDAP_LIST_FIRST(&sh->sh_sopool);
+					LDAP_LIST_REMOVE(so_right, so_link);
+					so_right->so_ptr = so_left->so_ptr + (1 << j);
+				} else {
+					so_right = LDAP_LIST_FIRST(&sh->sh_sopool);
+					LDAP_LIST_REMOVE(so_right, so_link);
+					so_right->so_ptr = so_left->so_ptr + (1 << j);
+				}
+				if (j == order + 1) {
+					ptr = so_left->so_ptr;
+					diff = (unsigned long)((char*)ptr -
+							(char*)sh->sh_base) >> (order+1);
+					sh->sh_map[order-order_start][diff>>3] |=
+							(1 << (diff & 0x7));
+					*ptr++ = size - sizeof(ber_len_t);
+					LDAP_LIST_INSERT_HEAD(
+							&sh->sh_free[j-1-order_start], so_right, so_link);
+					LDAP_LIST_INSERT_HEAD(&sh->sh_sopool, so_left, so_link);
+					return((void*)ptr);
+				} else {
+					LDAP_LIST_INSERT_HEAD(
+							&sh->sh_free[j-1-order_start], so_right, so_link);
+					LDAP_LIST_INSERT_HEAD(
+							&sh->sh_free[j-1-order_start], so_left, so_link);
+				}
+			}
+		} else {
+			Debug( LDAP_DEBUG_TRACE,
+				"slap_sl_malloc of %lu bytes failed, using ch_malloc\n",
+				(long)size, 0, 0);
+			return (void*)ch_malloc(size);
+		}
 	}
-	new = sh->h_last;
-	*new++ = size - sizeof(ber_len_t);
-	sh->h_last = (char *) sh->h_last + size;
-	
-	return( (void *)new );
 }
 
 void *
@@ -145,66 +362,262 @@ slap_sl_calloc( ber_len_t n, ber_len_t size, void *ctx )
 }
 
 void *
-slap_sl_realloc( void *ptr, ber_len_t size, void *ctx )
+slap_sl_realloc(void *ptr, ber_len_t size, void *ctx)
 {
 	struct slab_heap *sh = ctx;
-	int pad = 2*sizeof(int)-1;
-	ber_len_t *p = (ber_len_t *)ptr;
-	ber_len_t *new;
+	int size_shift;
+	int pad = 2*sizeof(int)-1, pad_shift;
+	int order_start = -1, order = -1;
+	struct slab_object *so;
+	ber_len_t *p = (ber_len_t *)ptr, *new;
+	unsigned long diff;
 
-	if ( ptr == NULL ) return slap_sl_malloc( size, ctx );
+	if (ptr == NULL)
+		return slap_sl_malloc(size, ctx);
 
 	/* Not our memory? */
-	if ( !sh || ptr < sh->h_base || ptr >= sh->h_end ) {
-		/* duplicate of ch_realloc behavior, oh well */
-		new = ber_memrealloc_x( ptr, size, NULL );
-		if (new ) {
+	if (!sh || ptr < sh->sh_base || ptr >= sh->sh_end) {
+		/* duplicate of realloc behavior, oh well */
+		new = ber_memrealloc_x(ptr, size, NULL);
+		if (new) {
 			return new;
 		}
-		Debug( LDAP_DEBUG_ANY, "ch_realloc of %lu bytes failed\n",
-			(long) size, 0, 0 );
-		assert( 0 );
+		Debug(LDAP_DEBUG_ANY, "ch_realloc of %lu bytes failed\n",
+				(long) size, 0, 0);
+		assert(0);
 		exit( EXIT_FAILURE );
 	}
 
-	if ( size == 0 ) {
-		slap_sl_free( ptr, ctx );
+	if (size == 0) {
+		slap_sl_free(ptr, ctx);
 		return NULL;
 	}
 
-	/* round up to doubleword boundary */
-	size += pad + sizeof( ber_len_t );
-	size &= ~pad;
-
-	/* Never shrink blocks */
-	if (size <= p[-1]) {
-		new = p;
+	if (sh->sh_stack) {
+		/* Never shrink blocks */
+		if (size <= p[-1]) {
+			new = p;
 	
-	/* If reallocing the last block, we can grow it */
-	} else if ( (char *)ptr + p[-1] == sh->h_last ) {
-		new = p;
-		sh->h_last = (char *) sh->h_last + size - p[-1];
-		p[-1] = size;
+		/* If reallocing the last block, we can grow it */
+		} else if ((char *)ptr + p[-1] == sh->sh_last) {
+			new = p;
+			sh->sh_last = (char *)sh->sh_last + size - p[-1];
+			p[-1] = size;
 	
-	/* Nowhere to grow, need to alloc and copy */
+		/* Nowhere to grow, need to alloc and copy */
+		} else {
+			new = slap_sl_malloc(size, ctx);
+			AC_MEMCPY(new, ptr, p[-1]);
+		}
+		return new;
 	} else {
-		new = slap_sl_malloc( size, ctx );
-		AC_MEMCPY( new, ptr, p[-1] );
+		void *newptr;
+		newptr = slap_sl_malloc(size, ctx);
+		if (size < p[-1]) {
+			AC_MEMCPY(newptr, ptr, size);
+		} else {
+			AC_MEMCPY(newptr, ptr, p[-1]);
+		}
+		slap_sl_free(ptr, ctx);
+		return newptr;
 	}
-	return new;
 }
 
 void
-slap_sl_free( void *ptr, void *ctx )
+slap_sl_free(void *ptr, void *ctx)
 {
 	struct slab_heap *sh = ctx;
-	ber_len_t *p = (ber_len_t *)ptr;
-
-	if ( !sh || ptr < sh->h_base || ptr >= sh->h_end ) {
-		ber_memfree_x( ptr, NULL );
-	} else if ( (char *)ptr + p[-1] == sh->h_last ) {
+	int size, size_shift, order_size;
+	int pad = 2*sizeof(int)-1, pad_shift;
+	ber_len_t *p = (ber_len_t *)ptr, *tmpp;
+	int order_start = -1, order = -1;
+	struct slab_object *so, *so_block;
+	unsigned long diff;
+	int i, k, inserted = 0;
+
+	Debug( LDAP_DEBUG_ANY, "slap_sl_free \n", 0, 0, 0);
+
+	if (!sh || ptr < sh->sh_base || ptr >= sh->sh_end) {
+		ber_memfree_x(ptr, NULL);
+	} else if (sh->sh_stack && (char *)ptr + p[-1] == sh->sh_last) {
 		p--;
-		sh->h_last = p;
+		sh->sh_last = p;
+	} else if (!sh->sh_stack) {
+		size = *(--p);
+		size_shift = size + sizeof(ber_len_t) - 1;
+		do {
+			order++;
+		} while (size_shift >>= 1);
+
+		pad_shift = pad - 1;
+		do {
+			order_start++;
+		} while (pad_shift >>= 1);
+
+		for (i = order, tmpp = p; i <= sh->sh_maxorder; i++) {
+			order_size = 1 << (i+1);
+			diff = (unsigned long)((char*)tmpp - (char*)sh->sh_base) >> (i+1);
+			sh->sh_map[i-order_start][diff>>3] &= (~(1 << (diff & 0x7)));
+			if (diff == ((diff>>1)<<1)) {
+				if (!(sh->sh_map[i-order_start][(diff+1)>>3] &
+						(1<<((diff+1)&0x7)))) {
+					so = LDAP_LIST_FIRST(&sh->sh_free[i-order_start]);
+					while (so) {
+						if ((char*)so->so_ptr == (char*)tmpp) {
+							LDAP_LIST_REMOVE( so, so_link );
+						} else if ((char*)so->so_ptr ==
+								(char*)tmpp + order_size) {
+							LDAP_LIST_REMOVE(so, so_link);
+							break;
+						}
+						so = LDAP_LIST_NEXT(so, so_link);
+					}
+					if (so) {
+						if (i < sh->sh_maxorder) {
+							inserted = 1;
+							so->so_ptr = tmpp;
+							LDAP_LIST_INSERT_HEAD(&sh->sh_free[i-order_start+1],
+									so, so_link);
+						}
+						continue;
+					} else {
+						if (LDAP_LIST_EMPTY(&sh->sh_sopool)) {
+							so_block = (struct slab_object *)ch_malloc(
+										SLAP_SLAB_SOBLOCK *
+										sizeof( struct slab_object));
+							so_block[0].so_blockhead = 1;
+							LDAP_LIST_INSERT_HEAD( &sh->sh_sopool,
+									&so_block[0], so_link );
+							for ( k = 1; k < SLAP_SLAB_SOBLOCK; k++ ) {
+								so_block[k].so_blockhead = 0;
+								LDAP_LIST_INSERT_HEAD( &sh->sh_sopool,
+										&so_block[k], so_link );
+							}
+							so = LDAP_LIST_FIRST(&sh->sh_sopool);
+							LDAP_LIST_REMOVE(so, so_link);
+							so->so_ptr = tmpp;
+						} else {
+							so = LDAP_LIST_FIRST(&sh->sh_sopool);
+							LDAP_LIST_REMOVE(so, so_link);
+							so->so_ptr = tmpp;
+						}
+						LDAP_LIST_INSERT_HEAD(&sh->sh_free[i-order_start],
+								so, so_link);
+						break;
+
+						Debug(LDAP_DEBUG_ANY, "slap_sl_free: "
+							"free object not found while bit is clear.\n",
+							0, 0, 0);
+						assert(so);
+
+					}
+				} else {
+					if (!inserted) {
+						if (LDAP_LIST_EMPTY(&sh->sh_sopool)) {
+							so_block = (struct slab_object *)ch_malloc(
+										SLAP_SLAB_SOBLOCK *
+										sizeof(struct slab_object));
+							so_block[0].so_blockhead = 1;
+							LDAP_LIST_INSERT_HEAD(&sh->sh_sopool,
+									&so_block[0], so_link);
+							for (k = 1; k < SLAP_SLAB_SOBLOCK; k++) {
+								so_block[k].so_blockhead = 0;
+								LDAP_LIST_INSERT_HEAD(&sh->sh_sopool,
+										&so_block[k], so_link);
+							}
+							so = LDAP_LIST_FIRST(&sh->sh_sopool);
+							LDAP_LIST_REMOVE(so, so_link);
+							so->so_ptr = tmpp;
+						} else {
+							so = LDAP_LIST_FIRST(&sh->sh_sopool);
+							LDAP_LIST_REMOVE(so, so_link);
+							so->so_ptr = tmpp;
+						}
+						LDAP_LIST_INSERT_HEAD(&sh->sh_free[i-order_start],
+								so, so_link);
+					}
+					break;
+				}
+			} else {
+				if (!(sh->sh_map[i-order_start][(diff-1)>>3] &
+						(1<<((diff-1)&0x7)))) {
+					so = LDAP_LIST_FIRST(&sh->sh_free[i-order_start]);
+					while (so) {
+						if ((char*)so->so_ptr == (char*)tmpp) {
+							LDAP_LIST_REMOVE(so, so_link);
+						} else if ((char*)tmpp == so->so_ptr + order_size) {
+							LDAP_LIST_REMOVE(so, so_link);
+							tmpp = so->so_ptr;
+							break;
+						}
+						so = LDAP_LIST_NEXT(so, so_link);
+					}
+					if (so) {
+						if (i < sh->sh_maxorder) {
+							inserted = 1;
+							LDAP_LIST_INSERT_HEAD(&sh->sh_free[i-order_start+1],									so, so_link);
+							continue;
+						}
+					} else {
+						if (LDAP_LIST_EMPTY(&sh->sh_sopool)) {
+							so_block = (struct slab_object *)ch_malloc(
+											SLAP_SLAB_SOBLOCK *
+											sizeof(struct slab_object));
+							so_block[0].so_blockhead = 1;
+							LDAP_LIST_INSERT_HEAD(&sh->sh_sopool,
+									&so_block[0], so_link);
+							for (k = 1; k < SLAP_SLAB_SOBLOCK; k++) {
+								so_block[k].so_blockhead = 0;
+								LDAP_LIST_INSERT_HEAD(&sh->sh_sopool,
+										&so_block[k], so_link );
+							}
+							so = LDAP_LIST_FIRST(&sh->sh_sopool);
+							LDAP_LIST_REMOVE(so, so_link);
+							so->so_ptr = tmpp;
+						} else {
+							so = LDAP_LIST_FIRST(&sh->sh_sopool);
+							LDAP_LIST_REMOVE(so, so_link);
+							so->so_ptr = tmpp;
+						}
+						LDAP_LIST_INSERT_HEAD(&sh->sh_free[i-order_start],
+								so, so_link);
+						break;
+
+						Debug(LDAP_DEBUG_ANY, "slap_sl_free: "
+							"free object not found while bit is clear.\n",
+							0, 0, 0 );
+						assert( so );
+
+					}
+				} else {
+					if ( !inserted ) {
+						if (LDAP_LIST_EMPTY(&sh->sh_sopool)) {
+							so_block = (struct slab_object *)ch_malloc(
+											SLAP_SLAB_SOBLOCK *
+											sizeof(struct slab_object));
+							so_block[0].so_blockhead = 1;
+							LDAP_LIST_INSERT_HEAD(&sh->sh_sopool,
+									&so_block[0], so_link );
+							for (k = 1; k < SLAP_SLAB_SOBLOCK; k++) {
+								so_block[k].so_blockhead = 0;
+								LDAP_LIST_INSERT_HEAD(&sh->sh_sopool,
+										&so_block[k], so_link );
+							}
+							so = LDAP_LIST_FIRST(&sh->sh_sopool);
+							LDAP_LIST_REMOVE(so, so_link);
+							so->so_ptr = tmpp;
+						} else {
+							so = LDAP_LIST_FIRST(&sh->sh_sopool);
+							LDAP_LIST_REMOVE(so, so_link);
+							so->so_ptr = tmpp;
+						}
+						LDAP_LIST_INSERT_HEAD(&sh->sh_free[i-order_start],
+								so, so_link);
+					}
+					break;
+				}
+			}
+		}
 	}
 }
 
@@ -219,11 +632,53 @@ slap_sl_context( void *ptr )
 #else
 	ctx = ldap_pvt_thread_pool_context();
 
-	ldap_pvt_thread_pool_getkey( ctx, (void *)slap_sl_mem_init, (void **)&sh, NULL );
+	ldap_pvt_thread_pool_getkey(ctx, (void *)slap_sl_mem_init,
+			(void **)&sh, NULL);
 #endif
 
-	if ( sh && ptr >= sh->h_base && ptr <= sh->h_end ) {
+	if (sh && ptr >= sh->sh_base && ptr <= sh->sh_end) {
 		return sh;
 	}
 	return NULL;
 }
+
+static void
+print_slheap(int level, void *ctx)
+{
+	struct slab_heap *sh = ctx;
+	int order_start = -1;
+	int pad = 2*sizeof(int)-1, pad_shift;
+	struct slab_object *so;
+	int i, j, once = 0;
+
+	if (!ctx) {
+		Debug(level, "NULL memctx\n", 0, 0, 0);
+		return;
+	}
+
+	pad_shift = pad - 1;
+	do {
+		order_start++;
+	} while (pad_shift >>= 1);
+
+	Debug(level, "sh->sh_maxorder=%d\n", sh->sh_maxorder, 0, 0);
+
+	for (i = order_start; i <= sh->sh_maxorder; i++) {
+		once = 0;
+		Debug(level, "order=%d\n", i, 0, 0);
+		for (j = 0; j < (1<<(sh->sh_maxorder-i))/8; j++) {
+			Debug(level, "%02x ", sh->sh_map[i-order_start][j], 0, 0);
+			once = 1;
+		}
+		if (!once) {
+			Debug(level, "%02x ", sh->sh_map[i-order_start][0], 0, 0);
+		}
+		Debug(level, "\n", 0, 0, 0);
+		Debug(level, "free list:\n", 0, 0, 0);
+		so = LDAP_LIST_FIRST(&sh->sh_free[i-order_start]);
+		while (so) {
+			Debug(level, "%x\n",so->so_ptr, 0, 0);
+			so = LDAP_LIST_NEXT(so, so_link);
+		}
+	}
+}
diff --git a/servers/slapd/slap.h b/servers/slapd/slap.h
index 464e7c637a..af6f8793cb 100644
--- a/servers/slapd/slap.h
+++ b/servers/slapd/slap.h
@@ -2596,6 +2596,8 @@ typedef int (SLAP_CTRL_PARSE_FN) LDAP_P((
 	LDAPControl *ctrl ));
 
 #define SLAP_SLAB_SIZE	(1024*1024)
+#define SLAP_SLAB_STACK 1
+#define SLAP_SLAB_SOBLOCK 64
 
 #if defined(LDAP_DEVEL) && defined(ENABLE_REWRITE)
 /* use librewrite for sasl-regexp */
@@ -2776,6 +2778,25 @@ typedef struct slap_component_syntax_info {
 
 #endif
 
+/* slab heap data structures */
+
+struct slab_object {
+    void *so_ptr;
+	int so_blockhead;
+    LDAP_LIST_ENTRY(slab_object) so_link;
+};
+
+struct slab_heap {
+    void *sh_base;
+    void *sh_last;
+    void *sh_end;
+	int sh_stack;
+	int sh_maxorder;
+    unsigned char **sh_map;
+    LDAP_LIST_HEAD( sh_freelist, slab_object ) *sh_free;
+	LDAP_LIST_HEAD( sh_so, slab_object ) sh_sopool;
+};
+
 #define SLAP_BACKEND_INIT_MODULE(b) \
 	int \
 	init_module( int argc, char *argv[] ) \