[lttng-dev] [PATCH 06/12] add max_nr_buckets argument

[Mathieu Desnoyers]

* Lai Jiangshan (laijs at cn.fujitsu.com) wrote:
> Signed-off-by: Lai Jiangshan <laijs at cn.fujitsu.com>

Merged, thanks!

[ Edit by Mathieu Desnoyers: clarify cds_lfht_new() description. ]

Mathieu

> ---
>  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 8282f09..4a611a1 100644
> --- a/rculfhash.c
> +++ b/rculfhash.c
> @@ -267,6 +267,7 @@ struct cds_lfht {
>  	struct rcu_table t;
>  	unsigned long min_alloc_buckets_order;
>  	unsigned long min_nr_alloc_buckets;
> +	unsigned long max_nr_buckets;
>  	int flags;
>  	/*
>  	 * We need to put the work threads offline (QSBR) when taking this
> @@ -1365,6 +1366,7 @@ 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_nr_alloc_buckets,
> +			unsigned long max_nr_buckets,
>  			int flags,
>  			void (*cds_lfht_call_rcu)(struct rcu_head *head,
>  					void (*func)(struct rcu_head *head)),
> @@ -1383,11 +1385,22 @@ struct cds_lfht *_cds_lfht_new(unsigned long init_size,
>  	/* min_nr_alloc_buckets must be power of two */
>  	if (!min_nr_alloc_buckets || (min_nr_alloc_buckets & (min_nr_alloc_buckets - 1)))
>  		return NULL;
> +
>  	/* init_size must be power of two */
>  	if (!init_size || (init_size & (init_size - 1)))
>  		return NULL;
> +
> +	if (!max_nr_buckets)
> +		max_nr_buckets = 1UL << (MAX_TABLE_ORDER - 1);
> +
> +	/* max_nr_buckets must be power of two */
> +	if (!max_nr_buckets || (max_nr_buckets & (max_nr_buckets - 1)))
> +		return NULL;
> +
>  	min_nr_alloc_buckets = max(min_nr_alloc_buckets, MIN_TABLE_SIZE);
>  	init_size = max(init_size, MIN_TABLE_SIZE);
> +	max_nr_buckets = max(max_nr_buckets, min_nr_alloc_buckets);
> +	init_size = min(init_size, max_nr_buckets);
>  	ht = calloc(1, sizeof(struct cds_lfht));
>  	assert(ht);
>  	ht->flags = flags;
> @@ -1407,6 +1420,7 @@ struct cds_lfht *_cds_lfht_new(unsigned long init_size,
>  	ht->t.resize_target = 1UL << order;
>  	ht->min_nr_alloc_buckets = min_nr_alloc_buckets;
>  	ht->min_alloc_buckets_order = get_count_order_ulong(min_nr_alloc_buckets);
> +	ht->max_nr_buckets = max_nr_buckets;
>  	cds_lfht_create_bucket(ht, 1UL << order);
>  	ht->t.size = 1UL << order;
>  	return ht;
> @@ -1766,6 +1780,7 @@ void resize_target_update_count(struct cds_lfht *ht,
>  				unsigned long count)
>  {
>  	count = max(count, MIN_TABLE_SIZE);
> +	count = min(count, ht->max_nr_buckets);
>  	uatomic_set(&ht->t.resize_target, count);
>  }
>  
> @@ -1823,6 +1838,7 @@ 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_nr_buckets);
>  	if (resize_target_grow(ht, target_size) >= target_size)
>  		return;
>  
> @@ -1841,6 +1857,7 @@ 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_nr_buckets);
>  	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 01ae01a..043a33a 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 d242ff6..bff883f 100644
> --- a/urcu/rculfhash.h
> +++ b/urcu/rculfhash.h
> @@ -99,6 +99,7 @@ enum {
>   */
>  struct cds_lfht *_cds_lfht_new(unsigned long init_size,
>  			unsigned long min_nr_alloc_buckets,
> +			unsigned long max_nr_buckets,
>  			int flags,
>  			void (*cds_lfht_call_rcu)(struct rcu_head *head,
>  				void (*func)(struct rcu_head *head)),
> @@ -113,8 +114,9 @@ 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_nr_alloc_buckets: 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_nr_alloc_buckets: the smallest allocation buckets size to use. Must be power of two.
> + * @max_nr_buckets: 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.
> @@ -138,10 +140,11 @@ 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_nr_alloc_buckets,
> +			unsigned long max_nr_buckets,
>  			int flags,
>  			pthread_attr_t *attr)
>  {
> -	return _cds_lfht_new(init_size, min_nr_alloc_buckets, flags,
> +	return _cds_lfht_new(init_size, min_nr_alloc_buckets, max_nr_buckets, 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