[ltt-dev] [PATCH 4/6 respin] Avoid alloc small memory pieces
Lai Jiangshan
laijs at cn.fujitsu.com
Thu Oct 27 06:31:40 EDT 2011
On 10/27/2011 05:56 PM, Mathieu Desnoyers wrote:
> * Lai Jiangshan (laijs at cn.fujitsu.com) wrote:
>> Add min_alloc_size(minimum allocation size) for allocation.
>>
>> Now we can gain better cache locality by
>> specifying larger minimum allocation size.
>>
>> Signed-off-by: Lai Jiangshan <laijs at cn.fujitsu.com>
>> ---
>> rculfhash.c | 42 ++++++++++++++++++++++++++++++------------
>> tests/test_urcu_hash.c | 2 +-
>> urcu/rculfhash.h | 5 ++++-
>> 3 files changed, 35 insertions(+), 14 deletions(-)
>>
>> diff --git a/rculfhash.c b/rculfhash.c
>> index a3dfbfe..32ea649 100644
>> --- a/rculfhash.c
>> +++ b/rculfhash.c
>> @@ -244,6 +244,8 @@ struct cds_lfht {
>> struct rcu_table t;
>> cds_lfht_hash_fct hash_fct;
>> cds_lfht_compare_fct compare_fct;
>> + unsigned long min_alloc_order;
>> + unsigned long min_alloc_size;
>> unsigned long hash_seed;
>> int flags;
>> /*
>> @@ -1076,7 +1078,7 @@ void init_table_populate_partition(struct cds_lfht *ht, unsigned long i,
>> {
>> unsigned long j;
>>
>> - assert(i > 0);
>> + assert(i > ht->min_alloc_order);
>> ht->cds_lfht_rcu_read_lock();
>> for (j = start; j < start + len; j++) {
>> struct cds_lfht_node *new_node =
>> @@ -1114,7 +1116,7 @@ void init_table(struct cds_lfht *ht,
>>
>> dbg_printf("init table: first_order %lu end_order %lu\n",
>> first_order, end_order);
>> - assert(first_order > 0);
>> + assert(first_order > ht->min_alloc_order);
>> for (i = first_order; i <= end_order; i++) {
>> unsigned long len;
>>
>> @@ -1177,7 +1179,7 @@ void remove_table_partition(struct cds_lfht *ht, unsigned long i,
>> {
>> unsigned long j;
>>
>> - assert(i > 0);
>> + assert(i > ht->min_alloc_order);
>> ht->cds_lfht_rcu_read_lock();
>> for (j = start; j < start + len; j++) {
>> struct cds_lfht_node *fini_node =
>> @@ -1215,7 +1217,7 @@ void fini_table(struct cds_lfht *ht,
>>
>> dbg_printf("fini table: first_order %lu end_order %lu\n",
>> first_order, end_order);
>> - assert(first_order > 0);
>> + assert(first_order > ht->min_alloc_order);
>> for (i = end_order; i >= first_order; i--) {
>> unsigned long len;
>>
>> @@ -1266,7 +1268,7 @@ void cds_lfht_create_dummy(struct cds_lfht *ht, unsigned long size)
>> struct _cds_lfht_node *prev, *node;
>> unsigned long order, len, i, j;
>>
>> - ht->t.tbl[0] = calloc(1, sizeof(struct _cds_lfht_node));
>> + ht->t.tbl[0] = calloc(1, ht->min_alloc_size * sizeof(struct _cds_lfht_node));
>> assert(ht->t.tbl[0]);
>>
>> dbg_printf("create dummy: order %lu index %lu hash %lu\n", 0, 0, 0);
>> @@ -1275,8 +1277,12 @@ void cds_lfht_create_dummy(struct cds_lfht *ht, unsigned long size)
>>
>> for (order = 1; order < get_count_order_ulong(size) + 1; order++) {
>> len = 1UL << (order - 1);
>> - ht->t.tbl[order] = calloc(1, len * sizeof(struct _cds_lfht_node));
>> - assert(ht->t.tbl[order]);
>> + if (order <= ht->min_alloc_order) {
>> + ht->t.tbl[order] = (void *)(ht->t.tbl[0]->nodes + len);
>
> not sure why we need to cast to void * here. I'm probably missing
> something. Can you enlighten me ? Is there any other way we could do
> this ?
The types are different between both site of "=".
this code simulate a "malloc", and since "malloc" return "void *",
so I use "void *" for cast.
"""
calloc() len * sizeof(struct _cds_lfht_node) bytes which locals at
((void *)ht->t.tbl[0]->nodes) + len * sizeof(struct _cds_lfht_node)
"""
Thanks,
Lai.
>
> Thanks,
>
> Mathieu
>
>> + } else {
>> + ht->t.tbl[order] = calloc(1, len * sizeof(struct _cds_lfht_node));
>> + assert(ht->t.tbl[order]);
>> + }
>>
>> i = 0;
>> prev = ht->t.tbl[i]->nodes;
>> @@ -1303,6 +1309,7 @@ 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,
>> + unsigned long min_alloc_size,
>> int flags,
>> void (*cds_lfht_call_rcu)(struct rcu_head *head,
>> void (*func)(struct rcu_head *head)),
>> @@ -1318,9 +1325,14 @@ struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct,
>> struct cds_lfht *ht;
>> unsigned long order;
>>
>> + /* 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)))
>> + if (!init_size || (init_size & (init_size - 1)))
>> return NULL;
>> + min_alloc_size = max(min_alloc_size, MIN_TABLE_SIZE);
>> + init_size = max(init_size, min_alloc_size);
>> ht = calloc(1, sizeof(struct cds_lfht));
>> assert(ht);
>> ht->hash_fct = hash_fct;
>> @@ -1339,10 +1351,12 @@ struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct,
>> /* this mutex should not nest in read-side C.S. */
>> pthread_mutex_init(&ht->resize_mutex, NULL);
>> ht->flags = flags;
>> - order = get_count_order_ulong(max(init_size, MIN_TABLE_SIZE));
>> + order = get_count_order_ulong(init_size);
>> ht->t.resize_target = 1UL << order;
>> cds_lfht_create_dummy(ht, 1UL << order);
>> ht->t.size = 1UL << order;
>> + ht->min_alloc_size = min_alloc_size;
>> + ht->min_alloc_order = get_count_order_ulong(min_alloc_size);
>> return ht;
>> }
>>
>> @@ -1560,7 +1574,11 @@ int cds_lfht_delete_dummy(struct cds_lfht *ht)
>> bit_reverse_ulong(ht->t.tbl[order]->nodes[i].reverse_hash));
>> assert(is_dummy(ht->t.tbl[order]->nodes[i].next));
>> }
>> - poison_free(ht->t.tbl[order]);
>> +
>> + if (order == ht->min_alloc_order)
>> + poison_free(ht->t.tbl[0]);
>> + else if (order > ht->min_alloc_order)
>> + poison_free(ht->t.tbl[order]);
>> }
>> return 0;
>> }
>> @@ -1661,7 +1679,7 @@ void _do_cds_lfht_shrink(struct cds_lfht *ht,
>> {
>> unsigned long old_order, new_order;
>>
>> - new_size = max(new_size, MIN_TABLE_SIZE);
>> + new_size = max(new_size, ht->min_alloc_size);
>> old_order = get_count_order_ulong(old_size);
>> new_order = get_count_order_ulong(new_size);
>> dbg_printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n",
>> @@ -1711,7 +1729,7 @@ static
>> void resize_target_update_count(struct cds_lfht *ht,
>> unsigned long count)
>> {
>> - count = max(count, MIN_TABLE_SIZE);
>> + count = max(count, ht->min_alloc_size);
>> uatomic_set(&ht->t.resize_target, count);
>> }
>>
>> diff --git a/tests/test_urcu_hash.c b/tests/test_urcu_hash.c
>> index db45c8c..70db8b3 100644
>> --- a/tests/test_urcu_hash.c
>> +++ b/tests/test_urcu_hash.c
>> @@ -888,7 +888,7 @@ int main(int argc, char **argv)
>> */
>> rcu_register_thread();
>> test_ht = cds_lfht_new(test_hash, test_compare, 0x42UL,
>> - init_hash_size,
>> + init_hash_size, 1,
>> opt_auto_resize ? CDS_LFHT_AUTO_RESIZE : 0, NULL);
>> ret = populate_hash();
>> assert(!ret);
>> diff --git a/urcu/rculfhash.h b/urcu/rculfhash.h
>> index 1376b5a..fd67b6b 100644
>> --- a/urcu/rculfhash.h
>> +++ b/urcu/rculfhash.h
>> @@ -103,6 +103,7 @@ 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,
>> + unsigned long min_alloc_size,
>> int flags,
>> void (*cds_lfht_call_rcu)(struct rcu_head *head,
>> void (*func)(struct rcu_head *head)),
>> @@ -121,6 +122,7 @@ struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct,
>> * @compare_fct: the key comparison function.
>> * @hash_seed: the seed for hash function.
>> * @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.
>> * @flags: hash table creation flags (can be combined with bitwise or: '|').
>> * 0: no flags.
>> * CDS_LFHT_AUTO_RESIZE: automatically resize hash table.
>> @@ -143,11 +145,12 @@ 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,
>> + unsigned long min_alloc_size,
>> int flags,
>> pthread_attr_t *attr)
>> {
>> return _cds_lfht_new(hash_fct, compare_fct, hash_seed,
>> - init_size, flags,
>> + init_size, min_alloc_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
>>
>
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