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| author | Eric Dumazet <edumazet@google.com> | 2013-02-07 16:41:02 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-02-08 17:55:48 -0500 |
| commit | 3807ff5899f892abb4f06747c245fd648a2acdc5 (patch) | |
| tree | a4c6bc690e612da44dab7e8beb71c5c0bdb8b6ba /drivers/net/macvlan.c | |
| parent | d527043040740f41192dfd71793f905a998ee4f6 (diff) | |
| download | lwn-3807ff5899f892abb4f06747c245fd648a2acdc5.tar.gz lwn-3807ff5899f892abb4f06747c245fd648a2acdc5.zip | |
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.c | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c index ce7c9268c740..e4b8078e88a9 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); } |