From patchwork Thu Jan 24 14:04:12 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [net-next, 1/6] net: cacheline adjust struct netns_frags for better frag performance Date: Thu, 24 Jan 2013 04:04:12 -0000 From: Jesper Dangaard Brouer X-Patchwork-Id: 215355 Message-Id: <20130124140405.14119.49967.stgit@dragon> To: Eric Dumazet , "David S. Miller" , Florian Westphal Cc: Jesper Dangaard Brouer , netdev@vger.kernel.org, Pablo Neira Ayuso , Cong Wang , "Patrick McHardy" , Herbert Xu , Daniel Borkmann 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 --- include/net/inet_frag.h | 5 ++++- 1 files changed, 4 insertions(+), 1 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html 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;