rculfhash: min size only needed on shrink, take nr cpus into account

[urcu.git] / rculfhash.c

diff --git a/rculfhash.c b/rculfhash.c
index 7e959fb4cd8228b161cbb7b4516ff36c4224270b..359de13c82cb427a691fae8645da3adf4c5f1b08 100644 (file)
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -246,7 +246,7 @@ struct cds_lfht {
        void (*cds_lfht_rcu_register_thread)(void);
        void (*cds_lfht_rcu_unregister_thread)(void);
        pthread_attr_t *resize_attr;    /* Resize threads attributes */
-       unsigned long count;            /* global approximate item count */
+       long count;                     /* global approximate item count */
        struct ht_items_count *percpu_count;    /* per-cpu item count */
 };
 
@@ -556,7 +556,7 @@ void ht_count_add(struct cds_lfht *ht, unsigned long size)
                return;
        percpu_count = uatomic_add_return(&ht->percpu_count[cpu].add, 1);
        if (unlikely(!(percpu_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) {
-               unsigned long count;
+               long count;
 
                dbg_printf("add percpu %lu\n", percpu_count);
                count = uatomic_add_return(&ht->count,
@@ -565,7 +565,7 @@ void ht_count_add(struct cds_lfht *ht, unsigned long size)
                if (!(count & (count - 1))) {
                        if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) < size)
                                return;
-                       dbg_printf("add set global %lu\n", count);
+                       dbg_printf("add set global %ld\n", count);
                        cds_lfht_resize_lazy_count(ht, size,
                                count >> (CHAIN_LEN_TARGET - 1));
                }
@@ -585,7 +585,7 @@ void ht_count_del(struct cds_lfht *ht, unsigned long size)
                return;
        percpu_count = uatomic_add_return(&ht->percpu_count[cpu].del, 1);
        if (unlikely(!(percpu_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) {
-               unsigned long count;
+               long count;
 
                dbg_printf("del percpu %lu\n", percpu_count);
                count = uatomic_add_return(&ht->count,
@@ -594,7 +594,13 @@ void ht_count_del(struct cds_lfht *ht, unsigned long size)
                if (!(count & (count - 1))) {
                        if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) >= size)
                                return;
-                       dbg_printf("del set global %lu\n", count);
+                       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) * (nr_cpus_mask + 1))
+                               return;
                        cds_lfht_resize_lazy_count(ht, size,
                                count >> (CHAIN_LEN_TARGET - 1));
                }