[ltt-dev] [PATCH 05/10 round10] add max_size arguemnt

[Lai Jiangshan]

On 11/22/2011 06:11 PM, Mathieu Desnoyers wrote:
> 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.

documented: "max_size: the max size of buckets for future growing"

Is max_bucket_size better?
and min_alloc_size need to be changed to min_alloc_bucket_size?

I'm not planing to add "max_size" for the number of elements in this
round or near future.

Thanks,
Lai

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