diff options
| author | David Held <drheld@google.com> | 2014-07-15 23:28:32 -0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2014-07-16 23:29:52 -0700 |
| commit | 2dc41cff7545d55c6294525c811594576f8e119c (patch) | |
| tree | cab09b28d188606139b1b50b661f42da157c52ba /net/ipv4/udp.c | |
| parent | 5cf3d46192fccf68b4a4759e4d7346e41c669a76 (diff) | |
| download | linux-rt-2dc41cff7545d55c6294525c811594576f8e119c.tar.gz | |
udp: Use hash2 for long hash1 chains in __udp*_lib_mcast_deliver.
Many multicast sources can have the same port which can result in a very
large list when hashing by port only. Hash by address and port instead
if this is the case. This makes multicast more similar to unicast.
On a 24-core machine receiving from 500 multicast sockets on the same
port, before this patch 80% of system CPU was used up by spin locking
and only ~25% of packets were successfully delivered.
With this patch, all packets are delivered and kernel overhead is ~8%
system CPU on spinlocks.
Signed-off-by: David Held <drheld@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/udp.c')
| -rw-r--r-- | net/ipv4/udp.c | 31 |
1 files changed, 21 insertions, 10 deletions
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index bbcc33737ef1..f31053b90ee0 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1619,6 +1619,8 @@ static void flush_stack(struct sock **stack, unsigned int count, if (skb1 && udp_queue_rcv_skb(sk, skb1) <= 0) skb1 = NULL; + + sock_put(sk); } if (unlikely(skb1)) kfree_skb(skb1); @@ -1651,10 +1653,20 @@ static int __udp4_lib_mcast_deliver(struct net *net, struct sk_buff *skb, unsigned short hnum = ntohs(uh->dest); struct udp_hslot *hslot = udp_hashslot(udptable, net, hnum); int dif = skb->dev->ifindex; - unsigned int i, count = 0; + unsigned int count = 0, offset = offsetof(typeof(*sk), sk_nulls_node); + unsigned int hash2 = 0, hash2_any = 0, use_hash2 = (hslot->count > 10); + + if (use_hash2) { + hash2_any = udp4_portaddr_hash(net, htonl(INADDR_ANY), hnum) & + udp_table.mask; + hash2 = udp4_portaddr_hash(net, daddr, hnum) & udp_table.mask; +start_lookup: + hslot = &udp_table.hash2[hash2]; + offset = offsetof(typeof(*sk), __sk_common.skc_portaddr_node); + } spin_lock(&hslot->lock); - sk_nulls_for_each(sk, node, &hslot->head) { + sk_nulls_for_each_entry_offset(sk, node, &hslot->head, offset) { if (__udp_is_mcast_sock(net, sk, uh->dest, daddr, uh->source, saddr, @@ -1664,24 +1676,23 @@ static int __udp4_lib_mcast_deliver(struct net *net, struct sk_buff *skb, count = 0; } stack[count++] = sk; + sock_hold(sk); } } - /* - * before releasing chain lock, we must take a reference on sockets - */ - for (i = 0; i < count; i++) - sock_hold(stack[i]); spin_unlock(&hslot->lock); + /* Also lookup *:port if we are using hash2 and haven't done so yet. */ + if (use_hash2 && hash2 != hash2_any) { + hash2 = hash2_any; + goto start_lookup; + } + /* * do the slow work with no lock held */ if (count) { flush_stack(stack, count, skb, count - 1); - - for (i = 0; i < count; i++) - sock_put(stack[i]); } else { kfree_skb(skb); } |