inet: frags: reorganize struct netns_frags

commit c2615cf5a761b32bf74e85bddc223dfff3d9b9f0 upstream.

Put the read-mostly fields in a separate cache line
at the beginning of struct netns_frags, to reduce
false sharing noticed in inet_frag_kill()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 4.4: adjust context]
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h
index 197c172..41a830b 100644 (file)
--- a/include/net/inet_frag.h
+++ b/include/net/inet_frag.h
@@ -4,15 +4,16 @@
 #include <linux/rhashtable.h>
 
 struct netns_frags {
-       struct rhashtable       rhashtable ____cacheline_aligned_in_smp;
-
-       /* Keep atomic mem on separate cachelines in structs that include it */
-       atomic_long_t           mem ____cacheline_aligned_in_smp;
        /* sysctls */
        long                    high_thresh;
        long                    low_thresh;
        int                     timeout;
        struct inet_frags       *f;
+
+       struct rhashtable       rhashtable ____cacheline_aligned_in_smp;
+
+       /* Keep atomic mem on separate cachelines in structs that include it */
+       atomic_long_t           mem ____cacheline_aligned_in_smp;
 };
 
 /**