[Bridge] [PATCH net-next 4/4] bridge: fdb: write to used and updated at most once per jiffy

[Nikolay Aleksandrov]

Writing once per jiffy is enough to limit the bridge's false sharing.
After this change the bridge doesn't show up in the local load HitM stats.

Suggested-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Nikolay Aleksandrov <nikolay at cumulusnetworks.com>
---
 net/bridge/br_fdb.c   | 3 ++-
 net/bridge/br_input.c | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index 5cbed5c0db88..5028691fa68a 100644
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -597,7 +597,8 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
 				fdb->dst = source;
 				fdb_modified = true;
 			}
-			fdb->updated = jiffies;
+			if (jiffies != fdb->updated)
+				fdb->updated = jiffies;
 			if (unlikely(added_by_user))
 				fdb->added_by_user = 1;
 			if (unlikely(fdb_modified))
diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index fba38d8a1a08..220943f920d2 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -198,7 +198,8 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
 		if (dst->is_local)
 			return br_pass_frame_up(skb);
 
-		dst->used = jiffies;
+		if (jiffies != dst->used)
+			dst->used = jiffies;
 		br_forward(dst->dst, skb, local_rcv, false);
 	} else {
 		if (!mcast_hit)
-- 
2.1.4