net: cacheline adjust struct netns_frags for better frag performance
This small cacheline adjustment of struct netns_frags improves
performance significantly for the fragmentation code.
Struct members 'lru_list' and 'mem' are both hot elements, and it
hurts performance, due to cacheline bouncing at every call point,
when they share a cacheline. Also notice, how mem is placed
together with 'high_thresh' and 'low_thresh', as they are used in
the compare operations together.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h
index 32786a0..91e7797 100644
--- a/include/net/inet_frag.h
+++ b/include/net/inet_frag.h
@@ -3,9 +3,12 @@
struct netns_frags {
int nqueues;
- atomic_t mem;
struct list_head lru_list;
+ /* Its important for performance to keep lru_list and mem on
+ * separate cachelines
+ */
+ atomic_t mem ____cacheline_aligned_in_smp;
/* sysctls */
int timeout;
int high_thresh;