Commit c2e213cf authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
Browse files

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: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6aebd940

include/linux/rhashtable.h

+4 −0
Original line number Diff line number Diff line
@@ -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;

lib/rhashtable.c

+8 −4
Original line number Diff line number Diff line
@@ -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);