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authorEric Dumazet <edumazet@google.com>2013-02-07 16:41:02 +0000
committerDavid S. Miller <davem@davemloft.net>2013-02-08 17:55:48 -0500
commit3807ff5899f892abb4f06747c245fd648a2acdc5 (patch)
treea4c6bc690e612da44dab7e8beb71c5c0bdb8b6ba /drivers/net/macvlan.c
parentd527043040740f41192dfd71793f905a998ee4f6 (diff)
macvlan: add a salt to mc_hash()
Some multicast addresses are common to all macvlans, so if a multicast message has a hash value collision, we have to deliver a copy to all macvlans, adding significant latency and possible packet drops if netdev_max_backlog limit is hit. Having a per macvlan hash function permits to reduce the impact of hash collisions. Suggested-by: Maciej Żenczykowski <maze@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Maciej Żenczykowski <maze@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/macvlan.c')
-rw-r--r--drivers/net/macvlan.c17
1 files changed, 13 insertions, 4 deletions
diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index ce7c9268c74..e4b8078e88a 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -127,10 +127,18 @@ static int macvlan_broadcast_one(struct sk_buff *skb,
return vlan->receive(skb);
}
-static unsigned int mc_hash(const unsigned char *addr)
+static u32 macvlan_hash_mix(const struct macvlan_dev *vlan)
+{
+ return (u32)(((unsigned long)vlan) >> L1_CACHE_SHIFT);
+}
+
+
+static unsigned int mc_hash(const struct macvlan_dev *vlan,
+ const unsigned char *addr)
{
u32 val = __get_unaligned_cpu32(addr + 2);
+ val ^= macvlan_hash_mix(vlan);
return hash_32(val, MACVLAN_MC_FILTER_BITS);
}
@@ -145,7 +153,7 @@ static void macvlan_broadcast(struct sk_buff *skb,
struct sk_buff *nskb;
unsigned int i;
int err;
- unsigned int hash = mc_hash(eth->h_dest);
+ unsigned int hash;
if (skb->protocol == htons(ETH_P_PAUSE))
return;
@@ -155,6 +163,7 @@ static void macvlan_broadcast(struct sk_buff *skb,
if (vlan->dev == src || !(vlan->mode & mode))
continue;
+ hash = mc_hash(vlan, eth->h_dest);
if (!test_bit(hash, vlan->mc_filter))
continue;
nskb = skb_clone(skb, GFP_ATOMIC);
@@ -424,10 +433,10 @@ static void macvlan_set_mac_lists(struct net_device *dev)
bitmap_zero(filter, MACVLAN_MC_FILTER_SZ);
netdev_for_each_mc_addr(ha, dev) {
- __set_bit(mc_hash(ha->addr), filter);
+ __set_bit(mc_hash(vlan, ha->addr), filter);
}
- __set_bit(mc_hash(dev->broadcast), filter);
+ __set_bit(mc_hash(vlan, dev->broadcast), filter);
bitmap_copy(vlan->mc_filter, filter, MACVLAN_MC_FILTER_SZ);
}