[PATCH net] rhashtable: ensure cache line alignment on bucket_table

[PATCH net] rhashtable: ensure cache line alignment on bucket_table

[Eric Dumazet]

From: Eric Dumazet <edumazet@google.com>

struct bucket_table contains mostly read fields :

size, locks_mask, locks.

Make sure these are not sharing a cache line with buckets[]

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 include/linux/rhashtable.h |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index 58851275fed9..cb2104be2135 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -54,10 +54,11 @@ struct rhash_head {
  * @buckets: size * hash buckets
  */
 struct bucket_table {
-	size_t				size;
-	unsigned int			locks_mask;
-	spinlock_t			*locks;
-	struct rhash_head __rcu		*buckets[];
+	size_t			size;
+	unsigned int		locks_mask;
+	spinlock_t		*locks;
+
+	struct rhash_head __rcu	*buckets[] ____cacheline_aligned_in_smp;
 };
 
 typedef u32 (*rht_hashfn_t)(const void *data, u32 len, u32 seed);

Re: [PATCH net] rhashtable: ensure cache line alignment on bucket_table

[Daniel Borkmann]

On 02/20/2015 03:48 PM, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@google.com>
>
> struct bucket_table contains mostly read fields :
>
> size, locks_mask, locks.
>
> Make sure these are not sharing a cache line with buckets[]
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Acked-by: Daniel Borkmann <daniel@iogearbox.net>

Re: [PATCH net] rhashtable: ensure cache line alignment on bucket_table

[Thomas Graf]

On 02/20/15 at 06:48am, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@google.com>
> 
> struct bucket_table contains mostly read fields :
> 
> size, locks_mask, locks.
> 
> Make sure these are not sharing a cache line with buckets[]
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Acked-by: Thomas Graf <tgraf@suug.ch>

Re: [PATCH net] rhashtable: ensure cache line alignment on bucket_table

[David Miller]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 20 Feb 2015 06:48:57 -0800

> From: Eric Dumazet <edumazet@google.com>
> 
> struct bucket_table contains mostly read fields :
> 
> size, locks_mask, locks.
> 
> Make sure these are not sharing a cache line with buckets[]
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Applied.