[ltt-dev] [PATCH 4/6 respin] Avoid alloc small memory pieces
Mathieu Desnoyers
mathieu.desnoyers at efficios.com
Thu Oct 27 05:56:29 EDT 2011
* 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 ?
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
>
--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
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