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rhashtable: Introduce max_size/min_size 

This patch adds the parameters max_size and min_size which are
meant to replace max_shift and min_shift.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu 2015-03-18 20:01:16 +11:00 committed by David S. Miller
parent 6aebd94084
commit c2e213cff7
2 changed files with 12 additions and 4 deletions
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4
include/linux/rhashtable.h
View File

@ -85,6 +85,8 @@ struct rhashtable;
* @head_offset: Offset of rhash_head in struct to be hashed
* @max_shift: Maximum number of shifts while expanding
* @min_shift: Minimum number of shifts while shrinking
* @max_size: Maximum size while expanding
* @min_size: Minimum size while shrinking
* @nulls_base: Base value to generate nulls marker
* @locks_mul: Number of bucket locks to allocate per cpu (default: 128)
* @hashfn: Function to hash key
@ -97,6 +99,8 @@ struct rhashtable_params {
size_t head_offset;
size_t max_shift;
size_t min_shift;
unsigned int max_size;
unsigned int min_size;
u32 nulls_base;
size_t locks_mul;
rht_hashfn_t hashfn;

12
lib/rhashtable.c
View File

@ -27,7 +27,7 @@
#include <linux/err.h>
#define HASH_DEFAULT_SIZE 64UL
#define HASH_MIN_SIZE 4UL
#define HASH_MIN_SIZE 4U
#define BUCKET_LOCKS_PER_CPU 128UL
/* Base bits plus 1 bit for nulls marker */
@ -188,7 +188,8 @@ static bool rht_grow_above_75(const struct rhashtable *ht,
{
/* Expand table when exceeding 75% load */
return atomic_read(&ht->nelems) > (tbl->size / 4 * 3) &&
(!ht->p.max_shift || tbl->size < (1 << ht->p.max_shift));
(!ht->p.max_shift || tbl->size < (1 << ht->p.max_shift)) &&
(!ht->p.max_size || tbl->size < ht->p.max_size);
}
/**
@ -201,7 +202,8 @@ static bool rht_shrink_below_30(const struct rhashtable *ht,
{
/* Shrink table beneath 30% load */
return atomic_read(&ht->nelems) < (tbl->size * 3 / 10) &&
tbl->size > (1 << ht->p.min_shift);
tbl->size > (1 << ht->p.min_shift) &&
tbl->size > ht->p.min_size;
}
static int rhashtable_rehash_one(struct rhashtable *ht, unsigned old_hash)
@ -873,7 +875,8 @@ EXPORT_SYMBOL_GPL(rhashtable_walk_stop);
static size_t rounded_hashtable_size(struct rhashtable_params *params)
{
return max(roundup_pow_of_two(params->nelem_hint * 4 / 3),
1UL << params->min_shift);
max(1UL << params->min_shift,
(unsigned long)params->min_size));
}
/**
@ -935,6 +938,7 @@ int rhashtable_init(struct rhashtable *ht, struct rhashtable_params *params)
params->min_shift = max_t(size_t, params->min_shift,
ilog2(HASH_MIN_SIZE));
params->min_size = max(params->min_size, HASH_MIN_SIZE);
if (params->nelem_hint)
size = rounded_hashtable_size(params);