* Lai Jiangshan ([email protected]) wrote:
> On 10/27/2011 05:56 PM, Mathieu Desnoyers wrote:
> > * Lai Jiangshan ([email protected]) 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 <[email protected]>
> >> ---
> >>  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)
> """

I think we can keep some typing information there by casting to struct
rcu_level *. I try to avoid void * as much as possible:

Fixed with:

commit eb631bf261cb0dad1db55ecb8fdda0fe761cf0c9
Author: Mathieu Desnoyers <[email protected]>
Date:   Fri Oct 28 08:18:30 2011 +0200

    rculfhash: Cast to struct rcu_level * instead of void * (cleanup)
    
    Signed-off-by: Mathieu Desnoyers <[email protected]>

diff --git a/rculfhash.c b/rculfhash.c
index 1f6ee71..ca63457 100644
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -1284,7 +1284,7 @@ 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);
                if (order <= ht->min_alloc_order) {
-                       ht->t.tbl[order] = (void *)(ht->t.tbl[0]->nodes + len);
+                       ht->t.tbl[order] = (struct rcu_level *) 
(ht->t.tbl[0]->nodes + len);
                } else {
                        ht->t.tbl[order] = calloc(1, len * sizeof(struct 
_cds_lfht_node));
                        assert(ht->t.tbl[order]);

> 
> 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
> >>
> > 
> 

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com

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