X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;f=rculfhash.c;h=ce1cbb79a55f4cc69ed729dddb170773a46d17d8;hb=cf77d1fac55a2b5c711d26b6fff22c68cf52dc72;hp=08d024c10996833462c94e1ea96162f609502195;hpb=f9c8034108dccf1434c99da6b5768aad0b8c10f1;p=urcu.git

diff --git a/rculfhash.c b/rculfhash.c
index 08d024c..ce1cbb7 100644
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -813,7 +813,6 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht,
 			new_next = flag_dummy(clear_flag(next));
 		else
 			new_next = clear_flag(next);
-		assert(new_next != NULL);
 		(void) uatomic_cmpxchg(&iter_prev->p.next, iter, new_next);
 		/* retry */
 	}
@@ -849,7 +848,6 @@ int _cds_lfht_remove(struct cds_lfht *ht, unsigned long size,
 			assert(is_dummy(next));
 		else
 			assert(!is_dummy(next));
-		assert(next != NULL);
 		old = uatomic_cmpxchg(&node->p.next, next,
 				      flag_removed(next));
 	} while (old != next);
@@ -881,32 +879,19 @@ end:
 		return -ENOENT;
 }
 
-static
-void init_table_hash(struct cds_lfht *ht, unsigned long i,
-		unsigned long len)
-{
-	unsigned long j;
-
-	for (j = 0; j < len; j++) {
-		struct cds_lfht_node *new_node =
-			(struct cds_lfht_node *) &ht->t.tbl[i]->nodes[j];
-
-		dbg_printf("init hash 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);
-		if (CMM_LOAD_SHARED(ht->in_progress_destroy))
-			break;
-	}
-}
-
 /*
  * Holding RCU read lock to protect _cds_lfht_add against memory
  * reclaim that could be performed by other call_rcu worker threads (ABA
  * problem).
+ *
+ * TODO: 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 dummy node population fairly with insertions.
  */
 static
-void init_table_link(struct cds_lfht *ht, unsigned long i, unsigned long len)
+void init_table_populate(struct cds_lfht *ht, unsigned long i, unsigned long len)
 {
 	unsigned long j;
 
@@ -916,8 +901,10 @@ void init_table_link(struct cds_lfht *ht, unsigned long i, unsigned long len)
 		struct cds_lfht_node *new_node =
 			(struct cds_lfht_node *) &ht->t.tbl[i]->nodes[j];
 
-		dbg_printf("init link: i %lu j %lu hash %lu\n",
+		dbg_printf("init populate: 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, !i ? 0 : (1UL << (i - 1)),
 				new_node, 0, 1);
 		if (CMM_LOAD_SHARED(ht->in_progress_destroy))
@@ -949,14 +936,11 @@ void init_table(struct cds_lfht *ht,
 		ht->t.tbl[i] = calloc(1, sizeof(struct rcu_level)
 				+ (len * sizeof(struct _cds_lfht_node)));
 
-		/* Set all dummy nodes reverse hash values for a level */
-		init_table_hash(ht, i, len);
-
 		/*
-		 * Link all dummy nodes into the table. Concurrent
-		 * add/remove are helping us.
+		 * Set all dummy nodes reverse hash values for a level and
+		 * link all dummy nodes into the table.
 		 */
-		init_table_link(ht, i, len);
+		init_table_populate(ht, i, len);
 
 		/*
 		 * Update table size.
@@ -989,6 +973,11 @@ void init_table(struct cds_lfht *ht,
  *
  * 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.
+ *
+ * TODO: 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(struct cds_lfht *ht, unsigned long i, unsigned long len)
@@ -1061,7 +1050,7 @@ void fini_table(struct cds_lfht *ht,
 	}
 }
 
-struct cds_lfht *cds_lfht_new(cds_lfht_hash_fct hash_fct,
+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,