Being able to turn off fdb "used" updates makes it possible to avoid
false-sharing on each packet transmit/receive for that fdb. The best way
to completely avoid false-sharing is by binding ports to CPUs so receive
will write to the "updated" field only on a single CPU and transmit to
that fdb will not touch the "used" field. The default is used_enabled =
1 to avoid breaking user-space, strongly suggest if not needed to set it
to 0.
Signed-off-by: Nikolay Aleksandrov <niko...@cumulusnetworks.com>
---
include/uapi/linux/if_link.h | 1 +
net/bridge/br_device.c | 1 +
net/bridge/br_input.c | 3 ++-
net/bridge/br_netlink.c | 10 +++++++++-
net/bridge/br_private.h | 1 +
net/bridge/br_sysfs_br.c | 23 +++++++++++++++++++++++
6 files changed, 37 insertions(+), 2 deletions(-)
diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index b9aa5641ebe5..8bcd234fed03 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -277,6 +277,7 @@ enum {
IFLA_BR_MCAST_STATS_ENABLED,
IFLA_BR_MCAST_IGMP_VERSION,
IFLA_BR_MCAST_MLD_VERSION,
+ IFLA_BR_USED_ENABLED,
__IFLA_BR_MAX,
};
diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index 89b414fd1901..b1fa1b031fea 100644
--- a/net/bridge/br_device.c
+++ b/net/bridge/br_device.c
@@ -408,6 +408,7 @@ void br_dev_setup(struct net_device *dev)
br->bridge_hello_time = br->hello_time = 2 * HZ;
br->bridge_forward_delay = br->forward_delay = 15 * HZ;
br->bridge_ageing_time = br->ageing_time = BR_DEFAULT_AGEING_TIME;
+ br->used_enabled = 1;
dev->max_mtu = ETH_MAX_MTU;
br_netfilter_rtable_init(br);
diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 855b72fbe1da..8a320901aaa7 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -197,7 +197,8 @@ 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 (br->used_enabled)
+ dst->used = jiffies;
br_forward(dst->dst, skb, local_rcv, false);
} else {
if (!mcast_hit)
diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index d63ad8337dcd..49272efaad00 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -851,6 +851,7 @@ static const struct nla_policy br_policy[IFLA_BR_MAX + 1] =
{
[IFLA_BR_MCAST_STATS_ENABLED] = { .type = NLA_U8 },
[IFLA_BR_MCAST_IGMP_VERSION] = { .type = NLA_U8 },
[IFLA_BR_MCAST_MLD_VERSION] = { .type = NLA_U8 },
+ [IFLA_BR_USED_ENABLED] = { .type = NLA_U8 },
};
static int br_changelink(struct net_device *brdev, struct nlattr *tb[],
@@ -1102,6 +1103,11 @@ static int br_changelink(struct net_device *brdev,
struct nlattr *tb[],
br->nf_call_arptables = val ? true : false;
}
#endif
+ if (data[IFLA_BR_USED_ENABLED]) {
+ u8 val = nla_get_u8(data[IFLA_BR_USED_ENABLED]);
+
+ br->used_enabled = !!val;
+ }
return 0;
}
@@ -1175,6 +1181,7 @@ static size_t br_get_size(const struct net_device *brdev)
nla_total_size(sizeof(u8)) + /* IFLA_BR_NF_CALL_IP6TABLES */
nla_total_size(sizeof(u8)) + /* IFLA_BR_NF_CALL_ARPTABLES */
#endif
+ nla_total_size(sizeof(u8)) + /* IFLA_BR_USED_ENABLED */
0;
}
@@ -1246,7 +1253,8 @@ static int br_fill_info(struct sk_buff *skb, const struct
net_device *brdev)
nla_put_u32(skb, IFLA_BR_MCAST_STARTUP_QUERY_CNT,
br->multicast_startup_query_count) ||
nla_put_u8(skb, IFLA_BR_MCAST_IGMP_VERSION,
- br->multicast_igmp_version))
+ br->multicast_igmp_version) ||
+ nla_put_u8(skb, IFLA_BR_USED_ENABLED, br->used_enabled))
return -EMSGSIZE;
#if IS_ENABLED(CONFIG_IPV6)
if (nla_put_u8(skb, IFLA_BR_MCAST_MLD_VERSION,
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 1e1b9a07e2da..4b6eb2393d7e 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -281,6 +281,7 @@ struct net_bridge {
struct net_device *dev;
struct pcpu_sw_netstats __percpu *stats;
/* These fields are accessed on each packet */
+ u8 used_enabled;
#ifdef CONFIG_BRIDGE_VLAN_FILTERING
u8 vlan_enabled;
u8 vlan_stats_enabled;
diff --git a/net/bridge/br_sysfs_br.c b/net/bridge/br_sysfs_br.c
index 0f4034934d56..22adc29e8721 100644
--- a/net/bridge/br_sysfs_br.c
+++ b/net/bridge/br_sysfs_br.c
@@ -334,6 +334,28 @@ static ssize_t flush_store(struct device *d,
}
static DEVICE_ATTR_WO(flush);
+static ssize_t used_enabled_show(struct device *d,
+ struct device_attribute *attr, char *buf)
+{
+ struct net_bridge *br = to_bridge(d);
+
+ return sprintf(buf, "%u\n", br->used_enabled);
+}
+
+static int set_used_enabled(struct net_bridge *br, unsigned long val)
+{
+ br->used_enabled = !!val;
+ return 0;
+}
+
+static ssize_t used_enabled_store(struct device *d,
+ struct device_attribute *attr,
+ const char *buf, size_t len)
+{
+ return store_bridge_parm(d, buf, len, set_used_enabled);
+}
+static DEVICE_ATTR_RW(used_enabled);
+
#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
static ssize_t multicast_router_show(struct device *d,
struct device_attribute *attr, char *buf)
@@ -829,6 +851,7 @@ static struct attribute *bridge_attrs[] = {
&dev_attr_gc_timer.attr,
&dev_attr_group_addr.attr,
&dev_attr_flush.attr,
+ &dev_attr_used_enabled.attr,
#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
&dev_attr_multicast_router.attr,
&dev_attr_multicast_snooping.attr,
--
2.1.4
