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authorHerbert Xu <herbert@gondor.apana.org.au>2015-03-18 10:01:16 +0100
committerDavid S. Miller <davem@davemloft.net>2015-03-18 17:46:40 +0100
commitc2e213cff701fce71a0aba8de82f2c2a4acf52ae (patch)
tree5b26d130b31b9a8acea6fca416021c08731d6e81
parentrhashtable: Remove shift from bucket_table (diff)
downloadlinux-c2e213cff701fce71a0aba8de82f2c2a4acf52ae.tar.xz
linux-c2e213cff701fce71a0aba8de82f2c2a4acf52ae.zip
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>
-rw-r--r--include/linux/rhashtable.h4
-rw-r--r--lib/rhashtable.c12
2 files changed, 12 insertions, 4 deletions
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index f16e85692959..81267fef85d7 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -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;
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 097400362467..c4061bbd0113 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -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);