arguemnt -> argument I think we need to discuss the semantic of max_size: here, you propose that max_size is just the number of buckets, but it does not limit the ability of the table to contain more elements than max_size.
IMHO, it would be nice to have max_size limit the number of elements that the table can accept, e.g. ensuring that insertion fails if the number of elements gets over the max_size threshold. It might not need to be an exact thing though, just giving an approximated upper limit might be fine (using the split-counters), as long as it is documented. Thanks, Mathieu * Lai Jiangshan ([email protected]) wrote: > Signed-off-by: Lai Jiangshan <[email protected]> > --- > rculfhash.c | 17 +++++++++++++++++ > tests/test_urcu_hash.c | 2 +- > urcu/rculfhash.h | 9 ++++++--- > 3 files changed, 24 insertions(+), 4 deletions(-) > > diff --git a/rculfhash.c b/rculfhash.c > index 2df133c..b7be893 100644 > --- a/rculfhash.c > +++ b/rculfhash.c > @@ -266,6 +266,7 @@ struct cds_lfht { > struct rcu_table t; > unsigned long min_alloc_order; > unsigned long min_alloc_size; > + unsigned long max_size; > int flags; > /* > * We need to put the work threads offline (QSBR) when taking this > @@ -1351,6 +1352,7 @@ void cds_lfht_create_bucket(struct cds_lfht *ht, > unsigned long size) > > struct cds_lfht *_cds_lfht_new(unsigned long init_size, > unsigned long min_alloc_size, > + unsigned long max_size, > int flags, > void (*cds_lfht_call_rcu)(struct rcu_head *head, > void (*func)(struct rcu_head *head)), > @@ -1369,11 +1371,22 @@ struct cds_lfht *_cds_lfht_new(unsigned long > init_size, > /* 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))) > return NULL; > + > + if (!max_size) > + max_size = 1UL << (MAX_TABLE_ORDER - 1); > + > + /* max_size must be power of two */ > + if (!max_size || (max_size & (max_size - 1))) > + return NULL; > + > min_alloc_size = max(min_alloc_size, MIN_TABLE_SIZE); > init_size = max(init_size, MIN_TABLE_SIZE); > + max_size = max(max_size, min_alloc_size); > + init_size = min(init_size, max_size); > ht = calloc(1, sizeof(struct cds_lfht)); > assert(ht); > ht->flags = flags; > @@ -1393,6 +1406,7 @@ struct cds_lfht *_cds_lfht_new(unsigned long 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); > + ht->max_size = max_size; > cds_lfht_create_bucket(ht, 1UL << order); > ht->t.size = 1UL << order; > return ht; > @@ -1752,6 +1766,7 @@ void resize_target_update_count(struct cds_lfht *ht, > unsigned long count) > { > count = max(count, MIN_TABLE_SIZE); > + count = min(count, ht->max_size); > uatomic_set(&ht->t.resize_target, count); > } > > @@ -1809,6 +1824,7 @@ void cds_lfht_resize_lazy_grow(struct cds_lfht *ht, > unsigned long size, int grow > { > unsigned long target_size = size << growth; > > + target_size = min(target_size, ht->max_size); > if (resize_target_grow(ht, target_size) >= target_size) > return; > > @@ -1827,6 +1843,7 @@ void cds_lfht_resize_lazy_count(struct cds_lfht *ht, > unsigned long size, > if (!(ht->flags & CDS_LFHT_AUTO_RESIZE)) > return; > count = max(count, MIN_TABLE_SIZE); > + count = min(count, ht->max_size); > if (count == size) > return; /* Already the right size, no resize needed */ > if (count > size) { /* lazy grow */ > diff --git a/tests/test_urcu_hash.c b/tests/test_urcu_hash.c > index b9e3e81..2961177 100644 > --- a/tests/test_urcu_hash.c > +++ b/tests/test_urcu_hash.c > @@ -967,7 +967,7 @@ int main(int argc, char **argv) > * thread from the point of view of resize. > */ > rcu_register_thread(); > - test_ht = cds_lfht_new(init_hash_size, min_hash_alloc_size, > + test_ht = cds_lfht_new(init_hash_size, min_hash_alloc_size, (1UL << 18), > (opt_auto_resize ? CDS_LFHT_AUTO_RESIZE : 0) | > CDS_LFHT_ACCOUNTING, NULL); > ret = populate_hash(); > diff --git a/urcu/rculfhash.h b/urcu/rculfhash.h > index c13d3df..2eefd2c 100644 > --- a/urcu/rculfhash.h > +++ b/urcu/rculfhash.h > @@ -98,6 +98,7 @@ enum { > */ > struct cds_lfht *_cds_lfht_new(unsigned long init_size, > unsigned long min_alloc_size, > + unsigned long max_size, > int flags, > void (*cds_lfht_call_rcu)(struct rcu_head *head, > void (*func)(struct rcu_head *head)), > @@ -112,8 +113,9 @@ struct cds_lfht *_cds_lfht_new(unsigned long init_size, > > /* > * cds_lfht_new - allocate a hash table. > - * @init_size: number of nodes to allocate initially. Must be power of two. > - * @min_alloc_size: the smallest allocation size to use. Must be power of > two. > + * @init_size: number of buckets to allocate initially. Must be power of two. > + * @min_alloc_size: the smallest allocation buckets size to use. Must be > power of two. > + * @max_size: the max size of buckets for future growing. Must be power of > two. > * @flags: hash table creation flags (can be combined with bitwise or: '|'). > * 0: no flags. > * CDS_LFHT_AUTO_RESIZE: automatically resize hash table. > @@ -134,10 +136,11 @@ struct cds_lfht *_cds_lfht_new(unsigned long init_size, > static inline > struct cds_lfht *cds_lfht_new(unsigned long init_size, > unsigned long min_alloc_size, > + unsigned long max_size, > int flags, > pthread_attr_t *attr) > { > - return _cds_lfht_new(init_size, min_alloc_size, flags, > + return _cds_lfht_new(init_size, min_alloc_size, max_size, flags, > call_rcu, synchronize_rcu, rcu_read_lock, > rcu_read_unlock, rcu_thread_offline, > rcu_thread_online, rcu_register_thread, > -- > 1.7.4.4 > -- Mathieu Desnoyers Operating System Efficiency R&D Consultant EfficiOS Inc. http://www.efficios.com _______________________________________________ ltt-dev mailing list [email protected] http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
