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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>
This commit is contained in:
Jesper Dangaard Brouer 2013-01-28 23:44:14 +00:00 committed by David S. Miller
parent 656a05c899
commit cd39a7890a
1 changed files with 4 additions and 1 deletions
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5
include/net/inet_frag.h
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@ -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;