diff mbox

[v1,2/14] rhashtable: Introduce max_size/min_size

Message ID E1YX61y-0005mR-MK@gondolin.me.apana.org.au
State Changes Requested, archived
Delegated to: David Miller
Headers show

Commit Message

Herbert Xu March 15, 2015, 10:44 a.m. UTC 
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>
---

 include/linux/rhashtable.h |    4 ++++
 lib/rhashtable.c           |   12 ++++++++----
 2 files changed, 12 insertions(+), 4 deletions(-)

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Comments

Sergei Shtylyov March 15, 2015, 3:12 p.m. UTC | #1 
Hello.

On 3/15/2015 1:44 PM, Herbert Xu wrote:

> 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>

[...]
> diff --git a/lib/rhashtable.c b/lib/rhashtable.c
> index 4a99c0c..5101e18 100644
> --- a/lib/rhashtable.c
> +++ b/lib/rhashtable.c
[...]
> @@ -872,7 +874,8 @@ 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,

    max_t(), perhaps?

> +		       (unsigned long)params->min_size));
>   }
>
>   /**
[...]

WBR, Sergei

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Herbert Xu March 15, 2015, 8:21 p.m. UTC | #2 
On Sun, Mar 15, 2015 at 06:12:02PM +0300, Sergei Shtylyov wrote:
> Hello.
> 
> On 3/15/2015 1:44 PM, Herbert Xu wrote:
> 
> >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>
> 
> [...]
> >diff --git a/lib/rhashtable.c b/lib/rhashtable.c
> >index 4a99c0c..5101e18 100644
> >--- a/lib/rhashtable.c
> >+++ b/lib/rhashtable.c
> [...]
> >@@ -872,7 +874,8 @@ 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,
> 
>    max_t(), perhaps?

max works just fine.  Besides, this max goes away a few patches
down.

Cheers,
diff mbox

Patch

diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index f16e856..81267fe 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 4a99c0c..5101e18 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)
@@ -872,7 +874,8 @@  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));
 }
 
 /**
@@ -934,6 +937,7 @@  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);