Nikolay Aleksandrov
2017-Feb-04 17:05 UTC
[Bridge] [PATCH net-next 4/4] bridge: fdb: write to used and updated at most once per jiffy
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
Stephen Hemminger
2017-Feb-07 16:46 UTC
[Bridge] [PATCH net-next] bridge: avoid unnecessary read of jiffies
Jiffies is volatile so read it once.
Signed-off-by: Stephen Hemminger <sthemmin at microsoft.com>
---
net/bridge/br_fdb.c | 6 ++++--
net/bridge/br_input.c | 6 ++++--
2 files changed, 8 insertions(+), 4 deletions(-)
diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index 5028691fa68a..5693168e88b6 100644
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -592,13 +592,15 @@ void br_fdb_update(struct net_bridge *br, struct
net_bridge_port *source,
br_warn(br, "received packet on %s with own address as source address
(addr:%pM, vlan:%u)\n",
source->dev->name, addr, vid);
} else {
+ unsigned long now = jiffies;
+
/* fastpath: update of existing entry */
if (unlikely(source != fdb->dst)) {
fdb->dst = source;
fdb_modified = true;
}
- if (jiffies != fdb->updated)
- fdb->updated = jiffies;
+ if (now != fdb->updated)
+ fdb->updated = now;
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 220943f920d2..4615a9b3e26c 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -195,11 +195,13 @@ int br_handle_frame_finish(struct net *net, struct sock
*sk, struct sk_buff *skb
}
if (dst) {
+ unsigned long now = jiffies;
+
if (dst->is_local)
return br_pass_frame_up(skb);
- if (jiffies != dst->used)
- dst->used = jiffies;
+ if (now != dst->used)
+ dst->used = now;
br_forward(dst->dst, skb, local_rcv, false);
} else {
if (!mcast_hit)
--
2.11.0