X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=rculfhash.c;h=5ad75833a37d77ba4f347d68834d0127e8bc574d;hp=0b3996416c270072b069fe700764515165bc50b5;hb=9d72a73f9c1fbbdd686a2e39a96f1917d5bb4f96;hpb=e1a68f1d99b97020243da2c47a81c74705dc3381

diff --git a/rculfhash.c b/rculfhash.c
index 0b39964..5ad7583 100644
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -4,6 +4,7 @@
  * Userspace RCU library - Lock-Free Resizable RCU Hash Table
  *
  * Copyright 2010-2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright 2011 - Lai Jiangshan <laijs@cn.fujitsu.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -45,7 +46,7 @@
  * - The resize operation executes concurrently with add/remove/lookup.
  * - Hash table nodes are contained within a split-ordered list. This
  *   list is ordered by incrementing reversed-bits-hash value.
- * - An index of dummy nodes is kept. These dummy nodes are the hash
+ * - An index of bucket nodes is kept. These bucket nodes are the hash
  *   table "buckets", and they are also chained together in the
  *   split-ordered list, which allows recursive expansion.
  * - The resize operation for small tables only allows expanding the hash table.
@@ -53,7 +54,7 @@
  *   operation.
  * - The resize operation for larger tables (and available through an
  *   API) allows both expanding and shrinking the hash table.
- * - Per-CPU Split-counters are used to keep track of the number of
+ * - Split-counters are used to keep track of the number of
  *   nodes within the hash table for automatic resize triggering.
  * - Resize operation initiated by long chain detection is executed by a
  *   call_rcu thread, which keeps lock-freedom of add and remove.
@@ -74,7 +75,7 @@
  *   successfully set the "removed" flag (with a cmpxchg) into a node's
  *   next pointer is considered to have succeeded its removal (and thus
  *   owns the node to reclaim). Because we garbage-collect starting from
- *   an invariant node (the start-of-bucket dummy node) up to the
+ *   an invariant node (the start-of-bucket bucket node) up to the
  *   "removed" node (or find a reverse-hash that is higher), we are sure
  *   that a successful traversal of the chain leads to a chain that is
  *   present in the linked-list (the start node is never removed) and
@@ -88,15 +89,35 @@
  *   for it do to so.
  * - A RCU "order table" indexed by log2(hash index) is copied and
  *   expanded by the resize operation. This order table allows finding
- *   the "dummy node" tables.
- * - There is one dummy node table per hash index order. The size of
- *   each dummy node table is half the number of hashes contained in
- *   this order.
- * - call_rcu is used to garbage-collect the old order table.
- * - The per-order dummy node tables contain a compact version of the
+ *   the "bucket node" tables.
+ * - There is one bucket node table per hash index order. The size of
+ *   each bucket node table is half the number of hashes contained in
+ *   this order (except for order 0).
+ * - synchronzie_rcu is used to garbage-collect the old bucket node table.
+ * - The per-order bucket node tables contain a compact version of the
  *   hash table nodes. These tables are invariant after they are
  *   populated into the hash table.
- * 
+ *
+ * Bucket node tables:
+ *
+ * hash table	hash table	the last	all bucket node tables
+ * order	size		bucket node	0   1   2   3   4   5   6(index)
+ * 				table size
+ * 0		1		1		1
+ * 1		2		1		1   1
+ * 2		4		2		1   1   2
+ * 3		8		4		1   1   2   4
+ * 4		16		8		1   1   2   4   8
+ * 5		32		16		1   1   2   4   8  16
+ * 6		64		32		1   1   2   4   8  16  32
+ *
+ * When growing/shrinking, we only focus on the last bucket node table
+ * which size is (!order ? 1 : (1 << (order -1))).
+ *
+ * Example for growing/shrinking:
+ * grow hash table from order 5 to 6: init the index=6 bucket node table
+ * shrink hash table from order 6 to 5: fini the index=6 bucket node table
+ *
  * A bit of ascii art explanation:
  * 
  * Order index is the off-by-one compare to the actual power of 2 because 
@@ -119,12 +140,9 @@
  * 
  * order              bits       reverse
  * 0               0  000        000
- *                 |
- * 1               |  1  001        100       <-    <-
- *                 |  |                        |     |
- * 2               |  |  2  010        010     |     |
+ * 1               |  1  001        100             <-
+ * 2               |  |  2  010        010    <-     |
  *                 |  |  |  3  011        110  | <-  |
- *                 |  |  |  |                  |  |  |
  * 3               -> |  |  |  4  100        001  |  |
  *                    -> |  |     5  101        101  |
  *                       -> |        6  110        011
@@ -144,7 +162,6 @@
 #include <urcu-call-rcu.h>
 #include <urcu/arch.h>
 #include <urcu/uatomic.h>
-#include <urcu/jhash.h>
 #include <urcu/compiler.h>
 #include <urcu/rculfhash.h>
 #include <stdio.h>
@@ -157,24 +174,36 @@
 #endif
 
 /*
- * Per-CPU split-counters lazily update the global counter each 1024
+ * Split-counters lazily update the global counter each 1024
  * addition/removal. It automatically keeps track of resize required.
  * We use the bucket length as indicator for need to expand for small
  * tables and machines lacking per-cpu data suppport.
  */
 #define COUNT_COMMIT_ORDER		10
+#define DEFAULT_SPLIT_COUNT_MASK	0xFUL
 #define CHAIN_LEN_TARGET		1
 #define CHAIN_LEN_RESIZE_THRESHOLD	3
 
 /*
- * Define the minimum table size. Protects against hash table resize overload
- * when too many entries are added quickly before the resize can complete.
- * This is especially the case if the table could be shrinked to a size of 1.
- * TODO: we might want to make the add/remove operations help the resize to
- * add or remove dummy nodes when a resize is ongoing to ensure upper-bound on
- * chain length.
+ * Define the minimum table size.
  */
-#define MIN_TABLE_SIZE			128
+#define MIN_TABLE_SIZE			1
+
+#if (CAA_BITS_PER_LONG == 32)
+#define MAX_TABLE_ORDER			32
+#else
+#define MAX_TABLE_ORDER			64
+#endif
+
+/*
+ * Minimum number of bucket nodes to touch per thread to parallelize grow/shrink.
+ */
+#define MIN_PARTITION_PER_THREAD_ORDER	12
+#define MIN_PARTITION_PER_THREAD	(1UL << MIN_PARTITION_PER_THREAD_ORDER)
+
+#ifndef min
+#define min(a, b)	((a) < (b) ? (a) : (b))
+#endif
 
 #ifndef max
 #define max(a, b)	((a) > (b) ? (a) : (b))
@@ -182,50 +211,120 @@
 
 /*
  * The removed flag needs to be updated atomically with the pointer.
- * The dummy flag does not require to be updated atomically with the
+ * It indicates that no node must attach to the node scheduled for
+ * removal, and that node garbage collection must be performed.
+ * The bucket flag does not require to be updated atomically with the
  * pointer, but it is added as a pointer low bit flag to save space.
  */
 #define REMOVED_FLAG		(1UL << 0)
-#define DUMMY_FLAG		(1UL << 1)
+#define BUCKET_FLAG		(1UL << 1)
 #define FLAGS_MASK		((1UL << 2) - 1)
 
+/* Value of the end pointer. Should not interact with flags. */
+#define END_VALUE		NULL
+
+/*
+ * ht_items_count: Split-counters counting the number of node addition
+ * and removal in the table. Only used if the CDS_LFHT_ACCOUNTING flag
+ * is set at hash table creation.
+ *
+ * These are free-running counters, never reset to zero. They count the
+ * number of add/remove, and trigger every (1 << COUNT_COMMIT_ORDER)
+ * operations to update the global counter. We choose a power-of-2 value
+ * for the trigger to deal with 32 or 64-bit overflow of the counter.
+ */
 struct ht_items_count {
-	unsigned long add, remove;
+	unsigned long add, del;
 } __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
 
+/*
+ * rcu_level: Contains the per order-index-level bucket node table. The
+ * size of each bucket node table is half the number of hashes contained
+ * in this order (except for order 0). The minimum allocation size
+ * parameter allows combining the bucket node arrays of the lowermost
+ * levels to improve cache locality for small index orders.
+ */
 struct rcu_level {
-	struct rcu_head head;
-	struct _cds_lfht_node nodes[0];
+	/* Note: manually update allocation length when adding a field */
+	struct cds_lfht_node nodes[0];
 };
 
+/*
+ * rcu_table: Contains the size and desired new size if a resize
+ * operation is in progress, as well as the statically-sized array of
+ * rcu_level pointers.
+ */
 struct rcu_table {
-	unsigned long size;	/* always a power of 2 */
+	unsigned long size;	/* always a power of 2, shared (RCU) */
 	unsigned long resize_target;
 	int resize_initiated;
-	struct rcu_head head;
-	struct rcu_level *tbl[0];
+	struct rcu_level *tbl[MAX_TABLE_ORDER];
 };
 
+/*
+ * cds_lfht: Top-level data structure representing a lock-free hash
+ * table. Defined in the implementation file to make it be an opaque
+ * cookie to users.
+ */
 struct cds_lfht {
-	struct rcu_table *t;		/* shared */
-	cds_lfht_hash_fct hash_fct;
-	cds_lfht_compare_fct compare_fct;
-	unsigned long hash_seed;
+	struct rcu_table t;
+	unsigned long min_alloc_order;
+	unsigned long min_alloc_size;
 	int flags;
+	/*
+	 * We need to put the work threads offline (QSBR) when taking this
+	 * mutex, because we use synchronize_rcu within this mutex critical
+	 * section, which waits on read-side critical sections, and could
+	 * therefore cause grace-period deadlock if we hold off RCU G.P.
+	 * completion.
+	 */
 	pthread_mutex_t resize_mutex;	/* resize mutex: add/del mutex */
 	unsigned int in_progress_resize, in_progress_destroy;
 	void (*cds_lfht_call_rcu)(struct rcu_head *head,
 		      void (*func)(struct rcu_head *head));
 	void (*cds_lfht_synchronize_rcu)(void);
-	unsigned long count;		/* global approximate item count */
-	struct ht_items_count *percpu_count;	/* per-cpu item count */
+	void (*cds_lfht_rcu_read_lock)(void);
+	void (*cds_lfht_rcu_read_unlock)(void);
+	void (*cds_lfht_rcu_thread_offline)(void);
+	void (*cds_lfht_rcu_thread_online)(void);
+	void (*cds_lfht_rcu_register_thread)(void);
+	void (*cds_lfht_rcu_unregister_thread)(void);
+	pthread_attr_t *resize_attr;	/* Resize threads attributes */
+	long count;			/* global approximate item count */
+	struct ht_items_count *split_count;	/* split item count */
 };
 
+/*
+ * rcu_resize_work: Contains arguments passed to RCU worker thread
+ * responsible for performing lazy resize.
+ */
 struct rcu_resize_work {
 	struct rcu_head head;
 	struct cds_lfht *ht;
 };
 
+/*
+ * partition_resize_work: Contains arguments passed to worker threads
+ * executing the hash table resize on partitions of the hash table
+ * assigned to each processor's worker thread.
+ */
+struct partition_resize_work {
+	pthread_t thread_id;
+	struct cds_lfht *ht;
+	unsigned long i, start, len;
+	void (*fct)(struct cds_lfht *ht, unsigned long i,
+		    unsigned long start, unsigned long len);
+};
+
+static
+void _cds_lfht_add(struct cds_lfht *ht,
+		cds_lfht_match_fct match,
+		const void *key,
+		unsigned long size,
+		struct cds_lfht_node *node,
+		struct cds_lfht_iter *unique_ret,
+		int bucket);
+
 /*
  * Algorithm to reverse bits in a word by lookup table, extended to
  * 64-bit words.
@@ -391,190 +490,195 @@ unsigned int fls_u32(uint32_t x)
 
 unsigned int fls_ulong(unsigned long x)
 {
-#if (CAA_BITS_PER_lONG == 32)
+#if (CAA_BITS_PER_LONG == 32)
 	return fls_u32(x);
 #else
 	return fls_u64(x);
 #endif
 }
 
+/*
+ * Return the minimum order for which x <= (1UL << order).
+ * Return -1 if x is 0.
+ */
 int get_count_order_u32(uint32_t x)
 {
-	int order;
+	if (!x)
+		return -1;
 
-	order = fls_u32(x) - 1;
-	if (x & (x - 1))
-		order++;
-	return order;
+	return fls_u32(x - 1);
 }
 
+/*
+ * Return the minimum order for which x <= (1UL << order).
+ * Return -1 if x is 0.
+ */
 int get_count_order_ulong(unsigned long x)
 {
-	int order;
+	if (!x)
+		return -1;
 
-	order = fls_ulong(x) - 1;
-	if (x & (x - 1))
-		order++;
-	return order;
+	return fls_ulong(x - 1);
 }
 
-static
-void cds_lfht_resize_lazy(struct cds_lfht *ht, struct rcu_table *t, int growth);
+#ifdef POISON_FREE
+#define poison_free(ptr)					\
+	do {							\
+		if (ptr) {					\
+			memset(ptr, 0x42, sizeof(*(ptr)));	\
+			free(ptr);				\
+		}						\
+	} while (0)
+#else
+#define poison_free(ptr)	free(ptr)
+#endif
 
-/*
- * If the sched_getcpu() and sysconf(_SC_NPROCESSORS_CONF) calls are
- * available, then we support hash table item accounting.
- * In the unfortunate event the number of CPUs reported would be
- * inaccurate, we use modulo arithmetic on the number of CPUs we got.
- */
-#if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF)
+static
+void cds_lfht_resize_lazy_grow(struct cds_lfht *ht, unsigned long size, int growth);
 
 static
-void cds_lfht_resize_lazy_count(struct cds_lfht *ht, struct rcu_table *t,
+void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size,
 				unsigned long count);
 
 static long nr_cpus_mask = -1;
+static long split_count_mask = -1;
+
+#if defined(HAVE_SYSCONF)
+static void ht_init_nr_cpus_mask(void)
+{
+	long maxcpus;
+
+	maxcpus = sysconf(_SC_NPROCESSORS_CONF);
+	if (maxcpus <= 0) {
+		nr_cpus_mask = -2;
+		return;
+	}
+	/*
+	 * round up number of CPUs to next power of two, so we
+	 * can use & for modulo.
+	 */
+	maxcpus = 1UL << get_count_order_ulong(maxcpus);
+	nr_cpus_mask = maxcpus - 1;
+}
+#else /* #if defined(HAVE_SYSCONF) */
+static void ht_init_nr_cpus_mask(void)
+{
+	nr_cpus_mask = -2;
+}
+#endif /* #else #if defined(HAVE_SYSCONF) */
 
 static
-struct ht_items_count *alloc_per_cpu_items_count(void)
+void alloc_split_items_count(struct cds_lfht *ht)
 {
 	struct ht_items_count *count;
 
-	switch (nr_cpus_mask) {
-	case -2:
-		return NULL;
-	case -1:
-	{
-		long maxcpus;
-
-		maxcpus = sysconf(_SC_NPROCESSORS_CONF);
-		if (maxcpus <= 0) {
-			nr_cpus_mask = -2;
-			return NULL;
-		}
-		/*
-		 * round up number of CPUs to next power of two, so we
-		 * can use & for modulo.
-		 */
-		maxcpus = 1UL << get_count_order_ulong(maxcpus);
-		nr_cpus_mask = maxcpus - 1;
+	if (nr_cpus_mask == -1)	{
+		ht_init_nr_cpus_mask();
+		if (nr_cpus_mask < 0)
+			split_count_mask = DEFAULT_SPLIT_COUNT_MASK;
+		else
+			split_count_mask = nr_cpus_mask;
 	}
-		/* Fall-through */
-	default:
-		return calloc(nr_cpus_mask + 1, sizeof(*count));
+
+	assert(split_count_mask >= 0);
+
+	if (ht->flags & CDS_LFHT_ACCOUNTING) {
+		ht->split_count = calloc(split_count_mask + 1, sizeof(*count));
+		assert(ht->split_count);
+	} else {
+		ht->split_count = NULL;
 	}
 }
 
 static
-void free_per_cpu_items_count(struct ht_items_count *count)
+void free_split_items_count(struct cds_lfht *ht)
 {
-	free(count);
+	poison_free(ht->split_count);
 }
 
+#if defined(HAVE_SCHED_GETCPU)
 static
-int ht_get_cpu(void)
+int ht_get_split_count_index(unsigned long hash)
 {
 	int cpu;
 
-	assert(nr_cpus_mask >= 0);
+	assert(split_count_mask >= 0);
 	cpu = sched_getcpu();
-	if (unlikely(cpu < 0))
-		return cpu;
+	if (caa_unlikely(cpu < 0))
+		return hash & split_count_mask;
 	else
-		return cpu & nr_cpus_mask;
+		return cpu & split_count_mask;
+}
+#else /* #if defined(HAVE_SCHED_GETCPU) */
+static
+int ht_get_split_count_index(unsigned long hash)
+{
+	return hash & split_count_mask;
 }
+#endif /* #else #if defined(HAVE_SCHED_GETCPU) */
 
 static
-void ht_count_add(struct cds_lfht *ht, struct rcu_table *t)
+void ht_count_add(struct cds_lfht *ht, unsigned long size, unsigned long hash)
 {
-	unsigned long percpu_count;
-	int cpu;
+	unsigned long split_count;
+	int index;
 
-	if (unlikely(!ht->percpu_count))
-		return;
-	cpu = ht_get_cpu();
-	if (unlikely(cpu < 0))
+	if (caa_unlikely(!ht->split_count))
 		return;
-	percpu_count = uatomic_add_return(&ht->percpu_count[cpu].add, 1);
-	if (unlikely(!(percpu_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) {
-		unsigned long count;
+	index = ht_get_split_count_index(hash);
+	split_count = uatomic_add_return(&ht->split_count[index].add, 1);
+	if (caa_unlikely(!(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) {
+		long count;
 
-		dbg_printf("add percpu %lu\n", percpu_count);
+		dbg_printf("add split count %lu\n", split_count);
 		count = uatomic_add_return(&ht->count,
 					   1UL << COUNT_COMMIT_ORDER);
 		/* If power of 2 */
 		if (!(count & (count - 1))) {
-			if ((count >> CHAIN_LEN_RESIZE_THRESHOLD)
-					< t->size)
+			if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) < size)
 				return;
-			dbg_printf("add set global %lu\n", count);
-			cds_lfht_resize_lazy_count(ht, t,
+			dbg_printf("add set global %ld\n", count);
+			cds_lfht_resize_lazy_count(ht, size,
 				count >> (CHAIN_LEN_TARGET - 1));
 		}
 	}
 }
 
 static
-void ht_count_remove(struct cds_lfht *ht, struct rcu_table *t)
+void ht_count_del(struct cds_lfht *ht, unsigned long size, unsigned long hash)
 {
-	unsigned long percpu_count;
-	int cpu;
+	unsigned long split_count;
+	int index;
 
-	if (unlikely(!ht->percpu_count))
-		return;
-	cpu = ht_get_cpu();
-	if (unlikely(cpu < 0))
+	if (caa_unlikely(!ht->split_count))
 		return;
-	percpu_count = uatomic_add_return(&ht->percpu_count[cpu].remove, -1);
-	if (unlikely(!(percpu_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) {
-		unsigned long count;
+	index = ht_get_split_count_index(hash);
+	split_count = uatomic_add_return(&ht->split_count[index].del, 1);
+	if (caa_unlikely(!(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) {
+		long count;
 
-		dbg_printf("remove percpu %lu\n", percpu_count);
+		dbg_printf("del split count %lu\n", split_count);
 		count = uatomic_add_return(&ht->count,
 					   -(1UL << COUNT_COMMIT_ORDER));
 		/* If power of 2 */
 		if (!(count & (count - 1))) {
-			if ((count >> CHAIN_LEN_RESIZE_THRESHOLD)
-					>= t->size)
+			if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) >= size)
 				return;
-			dbg_printf("remove set global %lu\n", count);
-			cds_lfht_resize_lazy_count(ht, t,
+			dbg_printf("del set global %ld\n", count);
+			/*
+			 * Don't shrink table if the number of nodes is below a
+			 * certain threshold.
+			 */
+			if (count < (1UL << COUNT_COMMIT_ORDER) * (split_count_mask + 1))
+				return;
+			cds_lfht_resize_lazy_count(ht, size,
 				count >> (CHAIN_LEN_TARGET - 1));
 		}
 	}
 }
 
-#else /* #if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) */
-
-static const long nr_cpus_mask = -1;
-
-static
-struct ht_items_count *alloc_per_cpu_items_count(void)
-{
-	return NULL;
-}
-
-static
-void free_per_cpu_items_count(struct ht_items_count *count)
-{
-}
-
-static
-void ht_count_add(struct cds_lfht *ht, struct rcu_table *t)
-{
-}
-
 static
-void ht_count_remove(struct cds_lfht *ht, struct rcu_table *t)
-{
-}
-
-#endif /* #else #if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) */
-
-
-static
-void check_resize(struct cds_lfht *ht, struct rcu_table *t,
-		  uint32_t chain_len)
+void check_resize(struct cds_lfht *ht, unsigned long size, uint32_t chain_len)
 {
 	unsigned long count;
 
@@ -591,7 +695,7 @@ void check_resize(struct cds_lfht *ht, struct rcu_table *t,
 		dbg_printf("WARNING: large chain length: %u.\n",
 			   chain_len);
 	if (chain_len >= CHAIN_LEN_RESIZE_THRESHOLD)
-		cds_lfht_resize_lazy(ht, t,
+		cds_lfht_resize_lazy_grow(ht, size,
 			get_count_order_u32(chain_len - (CHAIN_LEN_TARGET - 1)));
 }
 
@@ -614,19 +718,32 @@ struct cds_lfht_node *flag_removed(struct cds_lfht_node *node)
 }
 
 static
-int is_dummy(struct cds_lfht_node *node)
+int is_bucket(struct cds_lfht_node *node)
 {
-	return ((unsigned long) node) & DUMMY_FLAG;
+	return ((unsigned long) node) & BUCKET_FLAG;
 }
 
 static
-struct cds_lfht_node *flag_dummy(struct cds_lfht_node *node)
+struct cds_lfht_node *flag_bucket(struct cds_lfht_node *node)
 {
-	return (struct cds_lfht_node *) (((unsigned long) node) | DUMMY_FLAG);
+	return (struct cds_lfht_node *) (((unsigned long) node) | BUCKET_FLAG);
 }
- 
+
 static
-unsigned long _uatomic_max(unsigned long *ptr, unsigned long v)
+struct cds_lfht_node *get_end(void)
+{
+	return (struct cds_lfht_node *) END_VALUE;
+}
+
+static
+int is_end(struct cds_lfht_node *node)
+{
+	return clear_flag(node) == (struct cds_lfht_node *) END_VALUE;
+}
+
+static
+unsigned long _uatomic_xchg_monotonic_increase(unsigned long *ptr,
+		unsigned long v)
 {
 	unsigned long old1, old2;
 
@@ -636,86 +753,161 @@ unsigned long _uatomic_max(unsigned long *ptr, unsigned long v)
 		if (old2 >= v)
 			return old2;
 	} while ((old1 = uatomic_cmpxchg(ptr, old2, v)) != old2);
-	return v;
+	return old2;
 }
 
-static
-void cds_lfht_free_table_cb(struct rcu_head *head)
+static inline
+struct cds_lfht_node *bucket_at(struct cds_lfht *ht, unsigned long index)
 {
-	struct rcu_table *t =
-		caa_container_of(head, struct rcu_table, head);
-	free(t);
+	unsigned long order;
+
+	if ((__builtin_constant_p(index) && index == 0)
+			|| index < ht->min_alloc_size) {
+		dbg_printf("bucket index %lu order 0 aridx 0\n", index);
+		return &ht->t.tbl[0]->nodes[index];
+	}
+	/*
+	 * equivalent to get_count_order_ulong(index + 1), but optimizes
+	 * away the non-existing 0 special-case for
+	 * get_count_order_ulong.
+	 */
+	order = fls_ulong(index);
+	dbg_printf("bucket index %lu order %lu aridx %lu\n",
+		   index, order, index & ((1UL << (order - 1)) - 1));
+	return &ht->t.tbl[order]->nodes[index & ((1UL << (order - 1)) - 1)];
 }
 
-static
-void cds_lfht_free_level(struct rcu_head *head)
+static inline
+struct cds_lfht_node *lookup_bucket(struct cds_lfht *ht, unsigned long size,
+		unsigned long hash)
 {
-	struct rcu_level *l =
-		caa_container_of(head, struct rcu_level, head);
-	free(l);
+	assert(size > 0);
+	return bucket_at(ht, hash & (size - 1));
 }
 
 /*
  * Remove all logically deleted nodes from a bucket up to a certain node key.
  */
 static
-void _cds_lfht_gc_bucket(struct cds_lfht_node *dummy, struct cds_lfht_node *node)
+void _cds_lfht_gc_bucket(struct cds_lfht_node *bucket, struct cds_lfht_node *node)
 {
 	struct cds_lfht_node *iter_prev, *iter, *next, *new_next;
 
-	assert(!is_dummy(dummy));
-	assert(!is_removed(dummy));
-	assert(!is_dummy(node));
+	assert(!is_bucket(bucket));
+	assert(!is_removed(bucket));
+	assert(!is_bucket(node));
 	assert(!is_removed(node));
 	for (;;) {
-		iter_prev = dummy;
-		/* We can always skip the dummy node initially */
-		iter = rcu_dereference(iter_prev->p.next);
-		assert(iter_prev->p.reverse_hash <= node->p.reverse_hash);
+		iter_prev = bucket;
+		/* We can always skip the bucket node initially */
+		iter = rcu_dereference(iter_prev->next);
+		assert(!is_removed(iter));
+		assert(iter_prev->reverse_hash <= node->reverse_hash);
 		/*
-		 * We should never be called with dummy (start of chain)
+		 * We should never be called with bucket (start of chain)
 		 * and logically removed node (end of path compression
 		 * marker) being the actual same node. This would be a
 		 * bug in the algorithm implementation.
 		 */
-		assert(dummy != node);
+		assert(bucket != node);
 		for (;;) {
-			if (unlikely(!clear_flag(iter)))
+			if (caa_unlikely(is_end(iter)))
 				return;
-			if (likely(clear_flag(iter)->p.reverse_hash > node->p.reverse_hash))
+			if (caa_likely(clear_flag(iter)->reverse_hash > node->reverse_hash))
 				return;
-			next = rcu_dereference(clear_flag(iter)->p.next);
-			if (likely(is_removed(next)))
+			next = rcu_dereference(clear_flag(iter)->next);
+			if (caa_likely(is_removed(next)))
 				break;
 			iter_prev = clear_flag(iter);
 			iter = next;
 		}
 		assert(!is_removed(iter));
-		if (is_dummy(iter))
-			new_next = flag_dummy(clear_flag(next));
+		if (is_bucket(iter))
+			new_next = flag_bucket(clear_flag(next));
 		else
 			new_next = clear_flag(next);
-		(void) uatomic_cmpxchg(&iter_prev->p.next, iter, new_next);
+		(void) uatomic_cmpxchg(&iter_prev->next, iter, new_next);
+	}
+	return;
+}
+
+static
+int _cds_lfht_replace(struct cds_lfht *ht, unsigned long size,
+		struct cds_lfht_node *old_node,
+		struct cds_lfht_node *old_next,
+		struct cds_lfht_node *new_node)
+{
+	struct cds_lfht_node *bucket, *ret_next;
+
+	if (!old_node)	/* Return -ENOENT if asked to replace NULL node */
+		return -ENOENT;
+
+	assert(!is_removed(old_node));
+	assert(!is_bucket(old_node));
+	assert(!is_removed(new_node));
+	assert(!is_bucket(new_node));
+	assert(new_node != old_node);
+	for (;;) {
+		/* Insert after node to be replaced */
+		if (is_removed(old_next)) {
+			/*
+			 * Too late, the old node has been removed under us
+			 * between lookup and replace. Fail.
+			 */
+			return -ENOENT;
+		}
+		assert(!is_bucket(old_next));
+		assert(new_node != clear_flag(old_next));
+		new_node->next = clear_flag(old_next);
+		/*
+		 * Here is the whole trick for lock-free replace: we add
+		 * the replacement node _after_ the node we want to
+		 * replace by atomically setting its next pointer at the
+		 * same time we set its removal flag. Given that
+		 * the lookups/get next use an iterator aware of the
+		 * next pointer, they will either skip the old node due
+		 * to the removal flag and see the new node, or use
+		 * the old node, but will not see the new one.
+		 */
+		ret_next = uatomic_cmpxchg(&old_node->next,
+			      old_next, flag_removed(new_node));
+		if (ret_next == old_next)
+			break;		/* We performed the replacement. */
+		old_next = ret_next;
 	}
+
+	/*
+	 * Ensure that the old node is not visible to readers anymore:
+	 * lookup for the node, and remove it (along with any other
+	 * logically removed node) if found.
+	 */
+	bucket = lookup_bucket(ht, size, bit_reverse_ulong(old_node->reverse_hash));
+	_cds_lfht_gc_bucket(bucket, new_node);
+
+	assert(is_removed(rcu_dereference(old_node->next)));
+	return 0;
 }
 
+/*
+ * A non-NULL unique_ret pointer uses the "add unique" (or uniquify) add
+ * mode. A NULL unique_ret allows creation of duplicate keys.
+ */
 static
-struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, struct rcu_table *t,
-				struct cds_lfht_node *node, int unique, int dummy)
+void _cds_lfht_add(struct cds_lfht *ht,
+		cds_lfht_match_fct match,
+		const void *key,
+		unsigned long size,
+		struct cds_lfht_node *node,
+		struct cds_lfht_iter *unique_ret,
+		int bucket_flag)
 {
 	struct cds_lfht_node *iter_prev, *iter, *next, *new_node, *new_next,
-			*dummy_node;
-	struct _cds_lfht_node *lookup;
-	unsigned long hash, index, order;
+			*return_node;
+	struct cds_lfht_node *bucket;
 
-	assert(!is_dummy(node));
+	assert(!is_bucket(node));
 	assert(!is_removed(node));
-	if (!t->size) {
-		assert(dummy);
-		node->p.next = flag_dummy(NULL);
-		return node;	/* Initial first add (head) */
-	}
-	hash = bit_reverse_ulong(node->p.reverse_hash);
+	bucket = lookup_bucket(ht, size, bit_reverse_ulong(node->reverse_hash));
 	for (;;) {
 		uint32_t chain_len = 0;
 
@@ -723,385 +915,697 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, struct rcu_table *t,
 		 * iter_prev points to the non-removed node prior to the
 		 * insert location.
 		 */
-		index = hash & (t->size - 1);
-		order = get_count_order_ulong(index + 1);
-		lookup = &t->tbl[order]->nodes[index & ((!order ? 0 : (1UL << (order - 1))) - 1)];
-		iter_prev = (struct cds_lfht_node *) lookup;
-		/* We can always skip the dummy node initially */
-		iter = rcu_dereference(iter_prev->p.next);
-		assert(iter_prev->p.reverse_hash <= node->p.reverse_hash);
+		iter_prev = bucket;
+		/* We can always skip the bucket node initially */
+		iter = rcu_dereference(iter_prev->next);
+		assert(iter_prev->reverse_hash <= node->reverse_hash);
 		for (;;) {
-			/* TODO: check if removed */
-			if (unlikely(!clear_flag(iter)))
+			if (caa_unlikely(is_end(iter)))
+				goto insert;
+			if (caa_likely(clear_flag(iter)->reverse_hash > node->reverse_hash))
 				goto insert;
-			/* TODO: check if removed */
-			if (likely(clear_flag(iter)->p.reverse_hash > node->p.reverse_hash))
+
+			/* bucket node is the first node of the identical-hash-value chain */
+			if (bucket_flag && clear_flag(iter)->reverse_hash == node->reverse_hash)
 				goto insert;
-			next = rcu_dereference(clear_flag(iter)->p.next);
-			if (unlikely(is_removed(next)))
+
+			next = rcu_dereference(clear_flag(iter)->next);
+			if (caa_unlikely(is_removed(next)))
 				goto gc_node;
-			if (unique
-			    && !is_dummy(next)
-			    && !ht->compare_fct(node->key, node->key_len,
-						clear_flag(iter)->key,
-						clear_flag(iter)->key_len))
-				return clear_flag(iter);
+
+			/* uniquely add */
+			if (unique_ret
+			    && !is_bucket(next)
+			    && clear_flag(iter)->reverse_hash == node->reverse_hash) {
+				struct cds_lfht_iter d_iter = { .node = node, .next = iter, };
+
+				/*
+				 * uniquely adding inserts the node as the first
+				 * node of the identical-hash-value node chain.
+				 *
+				 * This semantic ensures no duplicated keys
+				 * should ever be observable in the table
+				 * (including observe one node by one node
+				 * by forward iterations)
+				 */
+				cds_lfht_next_duplicate(ht, match, key, &d_iter);
+				if (!d_iter.node)
+					goto insert;
+
+				*unique_ret = d_iter;
+				return;
+			}
+
 			/* Only account for identical reverse hash once */
-			if (iter_prev->p.reverse_hash != clear_flag(iter)->p.reverse_hash
-			    && !is_dummy(next))
-				check_resize(ht, t, ++chain_len);
+			if (iter_prev->reverse_hash != clear_flag(iter)->reverse_hash
+			    && !is_bucket(next))
+				check_resize(ht, size, ++chain_len);
 			iter_prev = clear_flag(iter);
 			iter = next;
 		}
+
 	insert:
 		assert(node != clear_flag(iter));
 		assert(!is_removed(iter_prev));
 		assert(!is_removed(iter));
 		assert(iter_prev != node);
-		if (!dummy)
-			node->p.next = clear_flag(iter);
+		if (!bucket_flag)
+			node->next = clear_flag(iter);
 		else
-			node->p.next = flag_dummy(clear_flag(iter));
-		if (is_dummy(iter))
-			new_node = flag_dummy(node);
+			node->next = flag_bucket(clear_flag(iter));
+		if (is_bucket(iter))
+			new_node = flag_bucket(node);
 		else
 			new_node = node;
-		if (uatomic_cmpxchg(&iter_prev->p.next, iter,
-				    new_node) != iter)
+		if (uatomic_cmpxchg(&iter_prev->next, iter,
+				    new_node) != iter) {
 			continue;	/* retry */
-		else
-			goto gc_end;
+		} else {
+			return_node = node;
+			goto end;
+		}
+
 	gc_node:
 		assert(!is_removed(iter));
-		if (is_dummy(iter))
-			new_next = flag_dummy(clear_flag(next));
+		if (is_bucket(iter))
+			new_next = flag_bucket(clear_flag(next));
 		else
 			new_next = clear_flag(next);
-		(void) uatomic_cmpxchg(&iter_prev->p.next, iter, new_next);
+		(void) uatomic_cmpxchg(&iter_prev->next, iter, new_next);
 		/* retry */
 	}
-gc_end:
-	/* Garbage collect logically removed nodes in the bucket */
-	index = hash & (t->size - 1);
-	order = get_count_order_ulong(index + 1);
-	lookup = &t->tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1)) - 1))];
-	dummy_node = (struct cds_lfht_node *) lookup;
-	_cds_lfht_gc_bucket(dummy_node, node);
-	return node;
+end:
+	if (unique_ret) {
+		unique_ret->node = return_node;
+		/* unique_ret->next left unset, never used. */
+	}
 }
 
 static
-int _cds_lfht_remove(struct cds_lfht *ht, struct rcu_table *t,
-		struct cds_lfht_node *node, int dummy_removal)
+int _cds_lfht_del(struct cds_lfht *ht, unsigned long size,
+		struct cds_lfht_node *node,
+		int bucket_removal)
 {
-	struct cds_lfht_node *dummy, *next, *old;
-	struct _cds_lfht_node *lookup;
-	int flagged = 0;
-	unsigned long hash, index, order;
+	struct cds_lfht_node *bucket, *next, *old;
+
+	if (!node)	/* Return -ENOENT if asked to delete NULL node */
+		return -ENOENT;
 
 	/* logically delete the node */
-	assert(!is_dummy(node));
+	assert(!is_bucket(node));
 	assert(!is_removed(node));
-	old = rcu_dereference(node->p.next);
+	old = rcu_dereference(node->next);
 	do {
+		struct cds_lfht_node *new_next;
+
 		next = old;
-		if (unlikely(is_removed(next)))
-			goto end;
-		if (dummy_removal)
-			assert(is_dummy(next));
+		if (caa_unlikely(is_removed(next)))
+			return -ENOENT;
+		if (bucket_removal)
+			assert(is_bucket(next));
 		else
-			assert(!is_dummy(next));
-		old = uatomic_cmpxchg(&node->p.next, next,
-				      flag_removed(next));
+			assert(!is_bucket(next));
+		new_next = flag_removed(next);
+		old = uatomic_cmpxchg(&node->next, next, new_next);
 	} while (old != next);
-
 	/* We performed the (logical) deletion. */
-	flagged = 1;
 
 	/*
 	 * Ensure that the node is not visible to readers anymore: lookup for
 	 * the node, and remove it (along with any other logically removed node)
 	 * if found.
 	 */
-	hash = bit_reverse_ulong(node->p.reverse_hash);
-	assert(t->size > 0);
-	index = hash & (t->size - 1);
-	order = get_count_order_ulong(index + 1);
-	lookup = &t->tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1)) - 1))];
-	dummy = (struct cds_lfht_node *) lookup;
-	_cds_lfht_gc_bucket(dummy, node);
-end:
+	bucket = lookup_bucket(ht, size, bit_reverse_ulong(node->reverse_hash));
+	_cds_lfht_gc_bucket(bucket, node);
+
+	assert(is_removed(rcu_dereference(node->next)));
+	return 0;
+}
+
+static
+void *partition_resize_thread(void *arg)
+{
+	struct partition_resize_work *work = arg;
+
+	work->ht->cds_lfht_rcu_register_thread();
+	work->fct(work->ht, work->i, work->start, work->len);
+	work->ht->cds_lfht_rcu_unregister_thread();
+	return NULL;
+}
+
+static
+void partition_resize_helper(struct cds_lfht *ht, unsigned long i,
+		unsigned long len,
+		void (*fct)(struct cds_lfht *ht, unsigned long i,
+			unsigned long start, unsigned long len))
+{
+	unsigned long partition_len;
+	struct partition_resize_work *work;
+	int thread, ret;
+	unsigned long nr_threads;
+
 	/*
-	 * Only the flagging action indicated that we (and no other)
-	 * removed the node from the hash.
+	 * Note: nr_cpus_mask + 1 is always power of 2.
+	 * We spawn just the number of threads we need to satisfy the minimum
+	 * partition size, up to the number of CPUs in the system.
 	 */
-	if (flagged) {
-		assert(is_removed(rcu_dereference(node->p.next)));
-		return 0;
-	} else
-		return -ENOENT;
+	if (nr_cpus_mask > 0) {
+		nr_threads = min(nr_cpus_mask + 1,
+				 len >> MIN_PARTITION_PER_THREAD_ORDER);
+	} else {
+		nr_threads = 1;
+	}
+	partition_len = len >> get_count_order_ulong(nr_threads);
+	work = calloc(nr_threads, sizeof(*work));
+	assert(work);
+	for (thread = 0; thread < nr_threads; thread++) {
+		work[thread].ht = ht;
+		work[thread].i = i;
+		work[thread].len = partition_len;
+		work[thread].start = thread * partition_len;
+		work[thread].fct = fct;
+		ret = pthread_create(&(work[thread].thread_id), ht->resize_attr,
+			partition_resize_thread, &work[thread]);
+		assert(!ret);
+	}
+	for (thread = 0; thread < nr_threads; thread++) {
+		ret = pthread_join(work[thread].thread_id, NULL);
+		assert(!ret);
+	}
+	free(work);
 }
 
+/*
+ * Holding RCU read lock to protect _cds_lfht_add against memory
+ * reclaim that could be performed by other call_rcu worker threads (ABA
+ * problem).
+ *
+ * When we reach a certain length, we can split this population phase over
+ * many worker threads, based on the number of CPUs available in the system.
+ * This should therefore take care of not having the expand lagging behind too
+ * many concurrent insertion threads by using the scheduler's ability to
+ * schedule bucket node population fairly with insertions.
+ */
 static
-void init_table(struct cds_lfht *ht, struct rcu_table *t,
-		unsigned long first_order, unsigned long len_order)
+void init_table_populate_partition(struct cds_lfht *ht, unsigned long i,
+				   unsigned long start, unsigned long len)
 {
-	unsigned long i, end_order;
+	unsigned long j, size = 1UL << (i - 1);
+
+	assert(i > ht->min_alloc_order);
+	ht->cds_lfht_rcu_read_lock();
+	for (j = size + start; j < size + start + len; j++) {
+		struct cds_lfht_node *new_node = bucket_at(ht, j);
+
+		assert(j >= size && j < (size << 1));
+		dbg_printf("init populate: order %lu index %lu hash %lu\n",
+			   i, j, j);
+		new_node->reverse_hash = bit_reverse_ulong(j);
+		_cds_lfht_add(ht, NULL, NULL, size, new_node, NULL, 1);
+	}
+	ht->cds_lfht_rcu_read_unlock();
+}
 
-	dbg_printf("init table: first_order %lu end_order %lu\n",
-		   first_order, first_order + len_order);
-	end_order = first_order + len_order;
-	t->size = !first_order ? 0 : (1UL << (first_order - 1));
-	for (i = first_order; i < end_order; i++) {
-		unsigned long j, len;
+static
+void init_table_populate(struct cds_lfht *ht, unsigned long i,
+			 unsigned long len)
+{
+	assert(nr_cpus_mask != -1);
+	if (nr_cpus_mask < 0 || len < 2 * MIN_PARTITION_PER_THREAD) {
+		ht->cds_lfht_rcu_thread_online();
+		init_table_populate_partition(ht, i, 0, len);
+		ht->cds_lfht_rcu_thread_offline();
+		return;
+	}
+	partition_resize_helper(ht, i, len, init_table_populate_partition);
+}
+
+static
+void init_table(struct cds_lfht *ht,
+		unsigned long first_order, unsigned long last_order)
+{
+	unsigned long i;
+
+	dbg_printf("init table: first_order %lu last_order %lu\n",
+		   first_order, last_order);
+	assert(first_order > ht->min_alloc_order);
+	for (i = first_order; i <= last_order; i++) {
+		unsigned long len;
 
-		len = !i ? 1 : 1UL << (i - 1);
+		len = 1UL << (i - 1);
 		dbg_printf("init order %lu len: %lu\n", i, len);
-		t->tbl[i] = calloc(1, sizeof(struct rcu_level)
-				+ (len * sizeof(struct _cds_lfht_node)));
-		for (j = 0; j < len; j++) {
-			struct cds_lfht_node *new_node =
-				(struct cds_lfht_node *) &t->tbl[i]->nodes[j];
-
-			dbg_printf("init entry: i %lu j %lu hash %lu\n",
-				   i, j, !i ? 0 : (1UL << (i - 1)) + j);
-			new_node->p.reverse_hash =
-				bit_reverse_ulong(!i ? 0 : (1UL << (i - 1)) + j);
-			(void) _cds_lfht_add(ht, t, new_node, 0, 1);
-			if (CMM_LOAD_SHARED(ht->in_progress_destroy))
-				break;
-		}
-		/* Update table size */
-		t->size = !i ? 1 : (1UL << i);
-		dbg_printf("init new size: %lu\n", t->size);
+
+		/* Stop expand if the resize target changes under us */
+		if (CMM_LOAD_SHARED(ht->t.resize_target) < (1UL << i))
+			break;
+
+		ht->t.tbl[i] = calloc(1, len * sizeof(struct cds_lfht_node));
+		assert(ht->t.tbl[i]);
+
+		/*
+		 * Set all bucket nodes reverse hash values for a level and
+		 * link all bucket nodes into the table.
+		 */
+		init_table_populate(ht, i, len);
+
+		/*
+		 * Update table size.
+		 */
+		cmm_smp_wmb();	/* populate data before RCU size */
+		CMM_STORE_SHARED(ht->t.size, 1UL << i);
+
+		dbg_printf("init new size: %lu\n", 1UL << i);
 		if (CMM_LOAD_SHARED(ht->in_progress_destroy))
 			break;
 	}
-	t->resize_target = t->size;
-	t->resize_initiated = 0;
+}
+
+/*
+ * Holding RCU read lock to protect _cds_lfht_remove against memory
+ * reclaim that could be performed by other call_rcu worker threads (ABA
+ * problem).
+ * For a single level, we logically remove and garbage collect each node.
+ *
+ * As a design choice, we perform logical removal and garbage collection on a
+ * node-per-node basis to simplify this algorithm. We also assume keeping good
+ * cache locality of the operation would overweight possible performance gain
+ * that could be achieved by batching garbage collection for multiple levels.
+ * However, this would have to be justified by benchmarks.
+ *
+ * Concurrent removal and add operations are helping us perform garbage
+ * collection of logically removed nodes. We guarantee that all logically
+ * removed nodes have been garbage-collected (unlinked) before call_rcu is
+ * invoked to free a hole level of bucket nodes (after a grace period).
+ *
+ * Logical removal and garbage collection can therefore be done in batch or on a
+ * node-per-node basis, as long as the guarantee above holds.
+ *
+ * When we reach a certain length, we can split this removal over many worker
+ * threads, based on the number of CPUs available in the system. This should
+ * take care of not letting resize process lag behind too many concurrent
+ * updater threads actively inserting into the hash table.
+ */
+static
+void remove_table_partition(struct cds_lfht *ht, unsigned long i,
+			    unsigned long start, unsigned long len)
+{
+	unsigned long j, size = 1UL << (i - 1);
+
+	assert(i > ht->min_alloc_order);
+	ht->cds_lfht_rcu_read_lock();
+	for (j = size + start; j < size + start + len; j++) {
+		struct cds_lfht_node *fini_node = bucket_at(ht, j);
+
+		assert(j >= size && j < (size << 1));
+		dbg_printf("remove entry: order %lu index %lu hash %lu\n",
+			   i, j, j);
+		fini_node->reverse_hash = bit_reverse_ulong(j);
+		(void) _cds_lfht_del(ht, size, fini_node, 1);
+	}
+	ht->cds_lfht_rcu_read_unlock();
 }
 
 static
-void fini_table(struct cds_lfht *ht, struct rcu_table *t,
-		unsigned long first_order, unsigned long len_order)
+void remove_table(struct cds_lfht *ht, unsigned long i, unsigned long len)
 {
-	long i, end_order;
 
-	dbg_printf("fini table: first_order %lu end_order %lu\n",
-		   first_order, first_order + len_order);
-	end_order = first_order + len_order;
-	assert(first_order > 0);
-	assert(t->size == (1UL << (end_order - 1)));
-	for (i = end_order - 1; i >= first_order; i--) {
-		unsigned long j, len;
+	assert(nr_cpus_mask != -1);
+	if (nr_cpus_mask < 0 || len < 2 * MIN_PARTITION_PER_THREAD) {
+		ht->cds_lfht_rcu_thread_online();
+		remove_table_partition(ht, i, 0, len);
+		ht->cds_lfht_rcu_thread_offline();
+		return;
+	}
+	partition_resize_helper(ht, i, len, remove_table_partition);
+}
+
+static
+void fini_table(struct cds_lfht *ht,
+		unsigned long first_order, unsigned long last_order)
+{
+	long i;
+	void *free_by_rcu = NULL;
+
+	dbg_printf("fini table: first_order %lu last_order %lu\n",
+		   first_order, last_order);
+	assert(first_order > ht->min_alloc_order);
+	for (i = last_order; i >= first_order; i--) {
+		unsigned long len;
 
-		len = !i ? 1 : 1UL << (i - 1);
+		len = 1UL << (i - 1);
 		dbg_printf("fini order %lu len: %lu\n", i, len);
+
+		/* Stop shrink if the resize target changes under us */
+		if (CMM_LOAD_SHARED(ht->t.resize_target) > (1UL << (i - 1)))
+			break;
+
+		cmm_smp_wmb();	/* populate data before RCU size */
+		CMM_STORE_SHARED(ht->t.size, 1UL << (i - 1));
+
 		/*
-		 * Update table size. Need to shrink this table prior to
-		 * removal so gc lookups use non-logically-removed dummy
-		 * nodes.
+		 * We need to wait for all add operations to reach Q.S. (and
+		 * thus use the new table for lookups) before we can start
+		 * releasing the old bucket nodes. Otherwise their lookup will
+		 * return a logically removed node as insert position.
 		 */
-		t->size = 1UL << (i - 1);
-		/* Unlink */
-		for (j = 0; j < len; j++) {
-			struct cds_lfht_node *fini_node =
-				(struct cds_lfht_node *) &t->tbl[i]->nodes[j];
-
-			dbg_printf("fini entry: i %lu j %lu hash %lu\n",
-				   i, j, !i ? 0 : (1UL << (i - 1)) + j);
-			fini_node->p.reverse_hash =
-				bit_reverse_ulong(!i ? 0 : (1UL << (i - 1)) + j);
-			(void) _cds_lfht_remove(ht, t, fini_node, 1);
-			if (CMM_LOAD_SHARED(ht->in_progress_destroy))
-				break;
-		}
-		ht->cds_lfht_call_rcu(&t->tbl[i]->head, cds_lfht_free_level);
-		dbg_printf("fini new size: %lu\n", t->size);
+		ht->cds_lfht_synchronize_rcu();
+		if (free_by_rcu)
+			free(free_by_rcu);
+
+		/*
+		 * Set "removed" flag in bucket nodes about to be removed.
+		 * Unlink all now-logically-removed bucket node pointers.
+		 * Concurrent add/remove operation are helping us doing
+		 * the gc.
+		 */
+		remove_table(ht, i, len);
+
+		free_by_rcu = ht->t.tbl[i];
+
+		dbg_printf("fini new size: %lu\n", 1UL << i);
 		if (CMM_LOAD_SHARED(ht->in_progress_destroy))
 			break;
 	}
-	t->resize_target = t->size;
-	t->resize_initiated = 0;
+
+	if (free_by_rcu) {
+		ht->cds_lfht_synchronize_rcu();
+		free(free_by_rcu);
+	}
+}
+
+static
+void cds_lfht_create_bucket(struct cds_lfht *ht, unsigned long size)
+{
+	struct cds_lfht_node *prev, *node;
+	unsigned long order, len, i;
+
+	ht->t.tbl[0] = calloc(1, ht->min_alloc_size * sizeof(struct cds_lfht_node));
+	assert(ht->t.tbl[0]);
+
+	dbg_printf("create bucket: order 0 index 0 hash 0\n");
+	node = bucket_at(ht, 0);
+	node->next = flag_bucket(get_end());
+	node->reverse_hash = 0;
+
+	for (order = 1; order < get_count_order_ulong(size) + 1; order++) {
+		len = 1UL << (order - 1);
+		if (order <= ht->min_alloc_order) {
+			ht->t.tbl[order] = (struct rcu_level *) (ht->t.tbl[0]->nodes + len);
+		} else {
+			ht->t.tbl[order] = calloc(1, len * sizeof(struct cds_lfht_node));
+			assert(ht->t.tbl[order]);
+		}
+
+		for (i = 0; i < len; i++) {
+			/*
+			 * Now, we are trying to init the node with the
+			 * hash=(len+i) (which is also a bucket with the
+			 * index=(len+i)) and insert it into the hash table,
+			 * so this node has to be inserted after the bucket
+			 * with the index=(len+i)&(len-1)=i. And because there
+			 * is no other non-bucket node nor bucket node with
+			 * larger index/hash inserted, so the bucket node
+			 * being inserted should be inserted directly linked
+			 * after the bucket node with index=i.
+			 */
+			prev = bucket_at(ht, i);
+			node = bucket_at(ht, len + i);
+
+			dbg_printf("create bucket: order %lu index %lu hash %lu\n",
+				   order, len + i, len + i);
+			node->reverse_hash = bit_reverse_ulong(len + i);
+
+			/* insert after prev */
+			assert(is_bucket(prev->next));
+			node->next = prev->next;
+			prev->next = flag_bucket(node);
+		}
+	}
 }
 
-struct cds_lfht *cds_lfht_new(cds_lfht_hash_fct hash_fct,
-			cds_lfht_compare_fct compare_fct,
-			unsigned long hash_seed,
-			unsigned long init_size,
+struct cds_lfht *_cds_lfht_new(unsigned long init_size,
+			unsigned long min_alloc_size,
 			int flags,
 			void (*cds_lfht_call_rcu)(struct rcu_head *head,
 					void (*func)(struct rcu_head *head)),
-			void (*cds_lfht_synchronize_rcu)(void))
+			void (*cds_lfht_synchronize_rcu)(void),
+			void (*cds_lfht_rcu_read_lock)(void),
+			void (*cds_lfht_rcu_read_unlock)(void),
+			void (*cds_lfht_rcu_thread_offline)(void),
+			void (*cds_lfht_rcu_thread_online)(void),
+			void (*cds_lfht_rcu_register_thread)(void),
+			void (*cds_lfht_rcu_unregister_thread)(void),
+			pthread_attr_t *attr)
 {
 	struct cds_lfht *ht;
 	unsigned long order;
 
+	/* min_alloc_size must be power of two */
+	if (!min_alloc_size || (min_alloc_size & (min_alloc_size - 1)))
+		return NULL;
 	/* init_size must be power of two */
-	if (init_size && (init_size & (init_size - 1)))
+	if (!init_size || (init_size & (init_size - 1)))
 		return NULL;
+	min_alloc_size = max(min_alloc_size, MIN_TABLE_SIZE);
+	init_size = max(init_size, min_alloc_size);
 	ht = calloc(1, sizeof(struct cds_lfht));
-	ht->hash_fct = hash_fct;
-	ht->compare_fct = compare_fct;
-	ht->hash_seed = hash_seed;
+	assert(ht);
+	ht->flags = flags;
 	ht->cds_lfht_call_rcu = cds_lfht_call_rcu;
 	ht->cds_lfht_synchronize_rcu = cds_lfht_synchronize_rcu;
-	ht->in_progress_resize = 0;
-	ht->percpu_count = alloc_per_cpu_items_count();
+	ht->cds_lfht_rcu_read_lock = cds_lfht_rcu_read_lock;
+	ht->cds_lfht_rcu_read_unlock = cds_lfht_rcu_read_unlock;
+	ht->cds_lfht_rcu_thread_offline = cds_lfht_rcu_thread_offline;
+	ht->cds_lfht_rcu_thread_online = cds_lfht_rcu_thread_online;
+	ht->cds_lfht_rcu_register_thread = cds_lfht_rcu_register_thread;
+	ht->cds_lfht_rcu_unregister_thread = cds_lfht_rcu_unregister_thread;
+	ht->resize_attr = attr;
+	alloc_split_items_count(ht);
 	/* this mutex should not nest in read-side C.S. */
 	pthread_mutex_init(&ht->resize_mutex, NULL);
-	order = get_count_order_ulong(max(init_size, MIN_TABLE_SIZE)) + 1;
-	ht->t = calloc(1, sizeof(struct cds_lfht)
-		       + (order * sizeof(struct rcu_level *)));
-	ht->t->size = 0;
-	ht->flags = flags;
-	pthread_mutex_lock(&ht->resize_mutex);
-	init_table(ht, ht->t, 0, order);
-	pthread_mutex_unlock(&ht->resize_mutex);
+	order = get_count_order_ulong(init_size);
+	ht->t.resize_target = 1UL << order;
+	ht->min_alloc_size = min_alloc_size;
+	ht->min_alloc_order = get_count_order_ulong(min_alloc_size);
+	cds_lfht_create_bucket(ht, 1UL << order);
+	ht->t.size = 1UL << order;
 	return ht;
 }
 
-struct cds_lfht_node *cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len)
+void cds_lfht_lookup(struct cds_lfht *ht, unsigned long hash,
+		cds_lfht_match_fct match, const void *key,
+		struct cds_lfht_iter *iter)
 {
-	struct rcu_table *t;
-	struct cds_lfht_node *node, *next;
-	struct _cds_lfht_node *lookup;
-	unsigned long hash, reverse_hash, index, order;
+	struct cds_lfht_node *node, *next, *bucket;
+	unsigned long reverse_hash, size;
 
-	hash = ht->hash_fct(key, key_len, ht->hash_seed);
 	reverse_hash = bit_reverse_ulong(hash);
 
-	t = rcu_dereference(ht->t);
-	index = hash & (t->size - 1);
-	order = get_count_order_ulong(index + 1);
-	lookup = &t->tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1))) - 1)];
-	dbg_printf("lookup hash %lu index %lu order %lu aridx %lu\n",
-		   hash, index, order, index & (!order ? 0 : ((1UL << (order - 1)) - 1)));
-	node = (struct cds_lfht_node *) lookup;
+	size = rcu_dereference(ht->t.size);
+	bucket = lookup_bucket(ht, size, hash);
+	/* We can always skip the bucket node initially */
+	node = rcu_dereference(bucket->next);
+	node = clear_flag(node);
 	for (;;) {
-		if (unlikely(!node))
+		if (caa_unlikely(is_end(node))) {
+			node = next = NULL;
 			break;
-		if (unlikely(node->p.reverse_hash > reverse_hash)) {
-			node = NULL;
+		}
+		if (caa_unlikely(node->reverse_hash > reverse_hash)) {
+			node = next = NULL;
 			break;
 		}
-		next = rcu_dereference(node->p.next);
-		if (likely(!is_removed(next))
-		    && !is_dummy(next)
-		    && likely(!ht->compare_fct(node->key, node->key_len, key, key_len))) {
+		next = rcu_dereference(node->next);
+		assert(node == clear_flag(node));
+		if (caa_likely(!is_removed(next))
+		    && !is_bucket(next)
+		    && node->reverse_hash == reverse_hash
+		    && caa_likely(match(node, key))) {
 				break;
 		}
 		node = clear_flag(next);
 	}
-	assert(!node || !is_dummy(rcu_dereference(node->p.next)));
-	return node;
+	assert(!node || !is_bucket(rcu_dereference(node->next)));
+	iter->node = node;
+	iter->next = next;
 }
 
-struct cds_lfht_node *cds_lfht_next(struct cds_lfht *ht,
-				struct cds_lfht_node *node)
+void cds_lfht_next_duplicate(struct cds_lfht *ht, cds_lfht_match_fct match,
+		const void *key, struct cds_lfht_iter *iter)
 {
-	struct cds_lfht_node *next;
+	struct cds_lfht_node *node, *next;
 	unsigned long reverse_hash;
-	void *key;
-	size_t key_len;
 
-	reverse_hash = node->p.reverse_hash;
-	key = node->key;
-	key_len = node->key_len;
-	next = rcu_dereference(node->p.next);
+	node = iter->node;
+	reverse_hash = node->reverse_hash;
+	next = iter->next;
 	node = clear_flag(next);
 
 	for (;;) {
-		if (unlikely(!node))
+		if (caa_unlikely(is_end(node))) {
+			node = next = NULL;
 			break;
-		if (unlikely(node->p.reverse_hash > reverse_hash)) {
-			node = NULL;
+		}
+		if (caa_unlikely(node->reverse_hash > reverse_hash)) {
+			node = next = NULL;
 			break;
 		}
-		next = rcu_dereference(node->p.next);
-		if (likely(!is_removed(next))
-		    && !is_dummy(next)
-		    && likely(!ht->compare_fct(node->key, node->key_len, key, key_len))) {
+		next = rcu_dereference(node->next);
+		if (caa_likely(!is_removed(next))
+		    && !is_bucket(next)
+		    && caa_likely(match(node, key))) {
 				break;
 		}
 		node = clear_flag(next);
 	}
-	assert(!node || !is_dummy(rcu_dereference(node->p.next)));
-	return node;
+	assert(!node || !is_bucket(rcu_dereference(node->next)));
+	iter->node = node;
+	iter->next = next;
 }
 
-void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node)
+void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter)
 {
-	struct rcu_table *t;
-	unsigned long hash;
+	struct cds_lfht_node *node, *next;
 
-	hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed);
-	node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash);
+	node = clear_flag(iter->next);
+	for (;;) {
+		if (caa_unlikely(is_end(node))) {
+			node = next = NULL;
+			break;
+		}
+		next = rcu_dereference(node->next);
+		if (caa_likely(!is_removed(next))
+		    && !is_bucket(next)) {
+				break;
+		}
+		node = clear_flag(next);
+	}
+	assert(!node || !is_bucket(rcu_dereference(node->next)));
+	iter->node = node;
+	iter->next = next;
+}
 
-	t = rcu_dereference(ht->t);
-	(void) _cds_lfht_add(ht, t, node, 0, 0);
-	ht_count_add(ht, t);
+void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter)
+{
+	/*
+	 * Get next after first bucket node. The first bucket node is the
+	 * first node of the linked list.
+	 */
+	iter->next = bucket_at(ht, 0)->next;
+	cds_lfht_next(ht, iter);
+}
+
+void cds_lfht_add(struct cds_lfht *ht, unsigned long hash,
+		struct cds_lfht_node *node)
+{
+	unsigned long size;
+
+	node->reverse_hash = bit_reverse_ulong((unsigned long) hash);
+	size = rcu_dereference(ht->t.size);
+	_cds_lfht_add(ht, NULL, NULL, size, node, NULL, 0);
+	ht_count_add(ht, size, hash);
 }
 
 struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
-					struct cds_lfht_node *node)
+				unsigned long hash,
+				cds_lfht_match_fct match,
+				const void *key,
+				struct cds_lfht_node *node)
 {
-	struct rcu_table *t;
-	unsigned long hash;
-	struct cds_lfht_node *ret;
+	unsigned long size;
+	struct cds_lfht_iter iter;
+
+	node->reverse_hash = bit_reverse_ulong((unsigned long) hash);
+	size = rcu_dereference(ht->t.size);
+	_cds_lfht_add(ht, match, key, size, node, &iter, 0);
+	if (iter.node == node)
+		ht_count_add(ht, size, hash);
+	return iter.node;
+}
 
-	hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed);
-	node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash);
+struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht,
+				unsigned long hash,
+				cds_lfht_match_fct match,
+				const void *key,
+				struct cds_lfht_node *node)
+{
+	unsigned long size;
+	struct cds_lfht_iter iter;
 
-	t = rcu_dereference(ht->t);
-	ret = _cds_lfht_add(ht, t, node, 1, 0);
-	if (ret != node)
-		ht_count_add(ht, t);
-	return ret;
+	node->reverse_hash = bit_reverse_ulong((unsigned long) hash);
+	size = rcu_dereference(ht->t.size);
+	for (;;) {
+		_cds_lfht_add(ht, match, key, size, node, &iter, 0);
+		if (iter.node == node) {
+			ht_count_add(ht, size, hash);
+			return NULL;
+		}
+
+		if (!_cds_lfht_replace(ht, size, iter.node, iter.next, node))
+			return iter.node;
+	}
+}
+
+int cds_lfht_replace(struct cds_lfht *ht, struct cds_lfht_iter *old_iter,
+		struct cds_lfht_node *new_node)
+{
+	unsigned long size;
+
+	size = rcu_dereference(ht->t.size);
+	return _cds_lfht_replace(ht, size, old_iter->node, old_iter->next,
+			new_node);
 }
 
-int cds_lfht_remove(struct cds_lfht *ht, struct cds_lfht_node *node)
+int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_iter *iter)
 {
-	struct rcu_table *t;
+	unsigned long size, hash;
 	int ret;
 
-	t = rcu_dereference(ht->t);
-	ret = _cds_lfht_remove(ht, t, node, 0);
-	if (!ret)
-		ht_count_remove(ht, t);
+	size = rcu_dereference(ht->t.size);
+	ret = _cds_lfht_del(ht, size, iter->node, 0);
+	if (!ret) {
+		hash = bit_reverse_ulong(iter->node->reverse_hash);
+		ht_count_del(ht, size, hash);
+	}
 	return ret;
 }
 
 static
-int cds_lfht_delete_dummy(struct cds_lfht *ht)
+int cds_lfht_delete_bucket(struct cds_lfht *ht)
 {
-	struct rcu_table *t;
 	struct cds_lfht_node *node;
-	struct _cds_lfht_node *lookup;
-	unsigned long order, i;
+	unsigned long order, i, size;
 
-	t = ht->t;
 	/* Check that the table is empty */
-	lookup = &t->tbl[0]->nodes[0];
-	node = (struct cds_lfht_node *) lookup;
+	node = bucket_at(ht, 0);
 	do {
-		node = clear_flag(node)->p.next;
-		if (!is_dummy(node))
+		node = clear_flag(node)->next;
+		if (!is_bucket(node))
 			return -EPERM;
 		assert(!is_removed(node));
-	} while (clear_flag(node));
-	/* Internal sanity check: all nodes left should be dummy */
-	for (order = 0; order < get_count_order_ulong(t->size) + 1; order++) {
+	} while (!is_end(node));
+	/*
+	 * size accessed without rcu_dereference because hash table is
+	 * being destroyed.
+	 */
+	size = ht->t.size;
+	/* Internal sanity check: all nodes left should be bucket */
+	for (order = 0; order < get_count_order_ulong(size) + 1; order++) {
 		unsigned long len;
 
 		len = !order ? 1 : 1UL << (order - 1);
 		for (i = 0; i < len; i++) {
 			dbg_printf("delete order %lu i %lu hash %lu\n",
 				order, i,
-				bit_reverse_ulong(t->tbl[order]->nodes[i].reverse_hash));
-			assert(is_dummy(t->tbl[order]->nodes[i].next));
+				bit_reverse_ulong(ht->t.tbl[order]->nodes[i].reverse_hash));
+			assert(is_bucket(ht->t.tbl[order]->nodes[i].next));
 		}
-		free(t->tbl[order]);
+
+		if (order == ht->min_alloc_order)
+			poison_free(ht->t.tbl[0]);
+		else if (order > ht->min_alloc_order)
+			poison_free(ht->t.tbl[order]);
+		/* Nothing to delete for order < ht->min_alloc_order */
 	}
 	return 0;
 }
@@ -1110,113 +1614,105 @@ int cds_lfht_delete_dummy(struct cds_lfht *ht)
  * Should only be called when no more concurrent readers nor writers can
  * possibly access the table.
  */
-int cds_lfht_destroy(struct cds_lfht *ht)
+int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr)
 {
 	int ret;
 
 	/* Wait for in-flight resize operations to complete */
-	CMM_STORE_SHARED(ht->in_progress_destroy, 1);
+	_CMM_STORE_SHARED(ht->in_progress_destroy, 1);
+	cmm_smp_mb();	/* Store destroy before load resize */
 	while (uatomic_read(&ht->in_progress_resize))
 		poll(NULL, 0, 100);	/* wait for 100ms */
-	ret = cds_lfht_delete_dummy(ht);
+	ret = cds_lfht_delete_bucket(ht);
 	if (ret)
 		return ret;
-	free(ht->t);
-	free_per_cpu_items_count(ht->percpu_count);
-	free(ht);
+	free_split_items_count(ht);
+	if (attr)
+		*attr = ht->resize_attr;
+	poison_free(ht);
 	return ret;
 }
 
 void cds_lfht_count_nodes(struct cds_lfht *ht,
+		long *approx_before,
 		unsigned long *count,
-		unsigned long *removed)
+		unsigned long *removed,
+		long *approx_after)
 {
-	struct rcu_table *t;
 	struct cds_lfht_node *node, *next;
-	struct _cds_lfht_node *lookup;
-	unsigned long nr_dummy = 0;
+	unsigned long nr_bucket = 0;
+
+	*approx_before = 0;
+	if (ht->split_count) {
+		int i;
+
+		for (i = 0; i < split_count_mask + 1; i++) {
+			*approx_before += uatomic_read(&ht->split_count[i].add);
+			*approx_before -= uatomic_read(&ht->split_count[i].del);
+		}
+	}
 
 	*count = 0;
 	*removed = 0;
 
-	t = rcu_dereference(ht->t);
-	/* Count non-dummy nodes in the table */
-	lookup = &t->tbl[0]->nodes[0];
-	node = (struct cds_lfht_node *) lookup;
+	/* Count non-bucket nodes in the table */
+	node = bucket_at(ht, 0);
 	do {
-		next = rcu_dereference(node->p.next);
+		next = rcu_dereference(node->next);
 		if (is_removed(next)) {
-			assert(!is_dummy(next));
-			(*removed)++;
-		} else if (!is_dummy(next))
+			if (!is_bucket(next))
+				(*removed)++;
+			else
+				(nr_bucket)++;
+		} else if (!is_bucket(next))
 			(*count)++;
 		else
-			(nr_dummy)++;
+			(nr_bucket)++;
 		node = clear_flag(next);
-	} while (node);
-	dbg_printf("number of dummy nodes: %lu\n", nr_dummy);
+	} while (!is_end(node));
+	dbg_printf("number of bucket nodes: %lu\n", nr_bucket);
+	*approx_after = 0;
+	if (ht->split_count) {
+		int i;
+
+		for (i = 0; i < split_count_mask + 1; i++) {
+			*approx_after += uatomic_read(&ht->split_count[i].add);
+			*approx_after -= uatomic_read(&ht->split_count[i].del);
+		}
+	}
 }
 
 /* called with resize mutex held */
 static
-void _do_cds_lfht_grow(struct cds_lfht *ht, struct rcu_table *old_t,
+void _do_cds_lfht_grow(struct cds_lfht *ht,
 		unsigned long old_size, unsigned long new_size)
 {
 	unsigned long old_order, new_order;
-	struct rcu_table *new_t;
-
-	old_order = get_count_order_ulong(old_size) + 1;
-	new_order = get_count_order_ulong(new_size) + 1;
-	printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n",
-	       old_size, old_order, new_size, new_order);
-	new_t = malloc(sizeof(struct cds_lfht)
-			+ (new_order * sizeof(struct rcu_level *)));
+
+	old_order = get_count_order_ulong(old_size);
+	new_order = get_count_order_ulong(new_size);
+	dbg_printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n",
+		   old_size, old_order, new_size, new_order);
 	assert(new_size > old_size);
-	memcpy(&new_t->tbl, &old_t->tbl,
-	       old_order * sizeof(struct rcu_level *));
-	init_table(ht, new_t, old_order, new_order - old_order);
-	/* Changing table and size atomically wrt lookups */
-	rcu_assign_pointer(ht->t, new_t);
-	ht->cds_lfht_call_rcu(&old_t->head, cds_lfht_free_table_cb);
+	init_table(ht, old_order + 1, new_order);
 }
 
 /* called with resize mutex held */
 static
-void _do_cds_lfht_shrink(struct cds_lfht *ht, struct rcu_table *old_t,
+void _do_cds_lfht_shrink(struct cds_lfht *ht,
 		unsigned long old_size, unsigned long new_size)
 {
 	unsigned long old_order, new_order;
-	struct rcu_table *new_t;
-
-	new_size = max(new_size, MIN_TABLE_SIZE);
-	old_order = get_count_order_ulong(old_size) + 1;
-	new_order = get_count_order_ulong(new_size) + 1;
-	printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n",
-	       old_size, old_order, new_size, new_order);
-	new_t = malloc(sizeof(struct cds_lfht)
-			+ (new_order * sizeof(struct rcu_level *)));
-	assert(new_size < old_size);
-	memcpy(&new_t->tbl, &old_t->tbl,
-	       new_order * sizeof(struct rcu_level *));
-	new_t->size = !new_order ? 1 : (1UL << (new_order - 1));
-	assert(new_t->size == new_size);
-	new_t->resize_target = new_t->size;
-	new_t->resize_initiated = 0;
 
-	/* Changing table and size atomically wrt lookups */
-	rcu_assign_pointer(ht->t, new_t);
-
-	/*
-	 * We need to wait for all add operations to reach Q.S. (and
-	 * thus use the new table for lookups) before we can start
-	 * releasing the old dummy nodes. Otherwise their lookup will
-	 * return a logically removed node as insert position.
-	 */
-	ht->cds_lfht_synchronize_rcu();
+	new_size = max(new_size, ht->min_alloc_size);
+	old_order = get_count_order_ulong(old_size);
+	new_order = get_count_order_ulong(new_size);
+	dbg_printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n",
+		   old_size, old_order, new_size, new_order);
+	assert(new_size < old_size);
 
-	/* Unlink and remove all now-unused dummy node pointers. */
-	fini_table(ht, old_t, new_order, old_order - new_order);
-	ht->cds_lfht_call_rcu(&old_t->head, cds_lfht_free_table_cb);
+	/* Remove and unlink all bucket nodes to remove. */
+	fini_table(ht, new_order + 1, old_order);
 }
 
 
@@ -1225,44 +1721,50 @@ static
 void _do_cds_lfht_resize(struct cds_lfht *ht)
 {
 	unsigned long new_size, old_size;
-	struct rcu_table *old_t;
-
-	old_t = ht->t;
-	old_size = old_t->size;
-	new_size = CMM_LOAD_SHARED(old_t->resize_target);
-	if (old_size < new_size)
-		_do_cds_lfht_grow(ht, old_t, old_size, new_size);
-	else if (old_size > new_size)
-		_do_cds_lfht_shrink(ht, old_t, old_size, new_size);
-	else
-		CMM_STORE_SHARED(old_t->resize_initiated, 0);
+
+	/*
+	 * Resize table, re-do if the target size has changed under us.
+	 */
+	do {
+		assert(uatomic_read(&ht->in_progress_resize));
+		if (CMM_LOAD_SHARED(ht->in_progress_destroy))
+			break;
+		ht->t.resize_initiated = 1;
+		old_size = ht->t.size;
+		new_size = CMM_LOAD_SHARED(ht->t.resize_target);
+		if (old_size < new_size)
+			_do_cds_lfht_grow(ht, old_size, new_size);
+		else if (old_size > new_size)
+			_do_cds_lfht_shrink(ht, old_size, new_size);
+		ht->t.resize_initiated = 0;
+		/* write resize_initiated before read resize_target */
+		cmm_smp_mb();
+	} while (ht->t.size != CMM_LOAD_SHARED(ht->t.resize_target));
 }
 
 static
-unsigned long resize_target_update(struct rcu_table *t,
-				   int growth_order)
+unsigned long resize_target_grow(struct cds_lfht *ht, unsigned long new_size)
 {
-	return _uatomic_max(&t->resize_target,
-			    t->size << growth_order);
+	return _uatomic_xchg_monotonic_increase(&ht->t.resize_target, new_size);
 }
 
 static
-void resize_target_update_count(struct rcu_table *t,
+void resize_target_update_count(struct cds_lfht *ht,
 				unsigned long count)
 {
-	count = max(count, MIN_TABLE_SIZE);
-	uatomic_set(&t->resize_target, count);
+	count = max(count, ht->min_alloc_size);
+	uatomic_set(&ht->t.resize_target, count);
 }
 
 void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size)
 {
-	struct rcu_table *t = rcu_dereference(ht->t);
-
-	resize_target_update_count(t, new_size);
-	CMM_STORE_SHARED(t->resize_initiated, 1);
+	resize_target_update_count(ht, new_size);
+	CMM_STORE_SHARED(ht->t.resize_initiated, 1);
+	ht->cds_lfht_rcu_thread_offline();
 	pthread_mutex_lock(&ht->resize_mutex);
 	_do_cds_lfht_resize(ht);
 	pthread_mutex_unlock(&ht->resize_mutex);
+	ht->cds_lfht_rcu_thread_online();
 }
 
 static
@@ -1272,50 +1774,78 @@ void do_resize_cb(struct rcu_head *head)
 		caa_container_of(head, struct rcu_resize_work, head);
 	struct cds_lfht *ht = work->ht;
 
+	ht->cds_lfht_rcu_thread_offline();
 	pthread_mutex_lock(&ht->resize_mutex);
 	_do_cds_lfht_resize(ht);
 	pthread_mutex_unlock(&ht->resize_mutex);
-	free(work);
+	ht->cds_lfht_rcu_thread_online();
+	poison_free(work);
 	cmm_smp_mb();	/* finish resize before decrement */
 	uatomic_dec(&ht->in_progress_resize);
 }
 
 static
-void cds_lfht_resize_lazy(struct cds_lfht *ht, struct rcu_table *t, int growth)
+void __cds_lfht_resize_lazy_launch(struct cds_lfht *ht)
 {
 	struct rcu_resize_work *work;
-	unsigned long target_size;
 
-	target_size = resize_target_update(t, growth);
-	if (!CMM_LOAD_SHARED(t->resize_initiated) && t->size < target_size) {
+	/* Store resize_target before read resize_initiated */
+	cmm_smp_mb();
+	if (!CMM_LOAD_SHARED(ht->t.resize_initiated)) {
 		uatomic_inc(&ht->in_progress_resize);
-		cmm_smp_mb();	/* increment resize count before calling it */
+		cmm_smp_mb();	/* increment resize count before load destroy */
+		if (CMM_LOAD_SHARED(ht->in_progress_destroy)) {
+			uatomic_dec(&ht->in_progress_resize);
+			return;
+		}
 		work = malloc(sizeof(*work));
 		work->ht = ht;
 		ht->cds_lfht_call_rcu(&work->head, do_resize_cb);
-		CMM_STORE_SHARED(t->resize_initiated, 1);
+		CMM_STORE_SHARED(ht->t.resize_initiated, 1);
 	}
 }
 
-#if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF)
+static
+void cds_lfht_resize_lazy_grow(struct cds_lfht *ht, unsigned long size, int growth)
+{
+	unsigned long target_size = size << growth;
+
+	if (resize_target_grow(ht, target_size) >= target_size)
+		return;
+
+	__cds_lfht_resize_lazy_launch(ht);
+}
 
+/*
+ * We favor grow operations over shrink. A shrink operation never occurs
+ * if a grow operation is queued for lazy execution. A grow operation
+ * cancels any pending shrink lazy execution.
+ */
 static
-void cds_lfht_resize_lazy_count(struct cds_lfht *ht, struct rcu_table *t,
+void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size,
 				unsigned long count)
 {
-	struct rcu_resize_work *work;
-
 	if (!(ht->flags & CDS_LFHT_AUTO_RESIZE))
 		return;
-	resize_target_update_count(t, count);
-	if (!CMM_LOAD_SHARED(t->resize_initiated)) {
-		uatomic_inc(&ht->in_progress_resize);
-		cmm_smp_mb();	/* increment resize count before calling it */
-		work = malloc(sizeof(*work));
-		work->ht = ht;
-		ht->cds_lfht_call_rcu(&work->head, do_resize_cb);
-		CMM_STORE_SHARED(t->resize_initiated, 1);
+	count = max(count, ht->min_alloc_size);
+	if (count == size)
+		return;		/* Already the right size, no resize needed */
+	if (count > size) {	/* lazy grow */
+		if (resize_target_grow(ht, count) >= count)
+			return;
+	} else {		/* lazy shrink */
+		for (;;) {
+			unsigned long s;
+
+			s = uatomic_cmpxchg(&ht->t.resize_target, size, count);
+			if (s == size)
+				break;	/* no resize needed */
+			if (s > size)
+				return;	/* growing is/(was just) in progress */
+			if (s <= count)
+				return;	/* some other thread do shrink */
+			size = s;
+		}
 	}
+	__cds_lfht_resize_lazy_launch(ht);
 }
-
-#endif