| Message ID | 20111221134944.52223cdf@nehalam.linuxnetplumber.net |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Stephen Hemminger <shemminger@vyatta.com> Date: Wed, 21 Dec 2011 13:49:44 -0800 > @@ -960,7 +960,7 @@ static int netlink_broadcast_deliver(str > skb_set_owner_r(skb, sk); > skb_queue_tail(&sk->sk_receive_queue, skb); > sk->sk_data_ready(sk, skb->len); > - return atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf; > + return atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf / 2; > } Please mirror the logic we use in the generic socket code to do this on the send side, namely use something like: return (atomic_read(&sk->sk_rmem_alloc) << 1) > sk->sk_rcvbuf; because sk_rcvbuf is an int and this "/ 2" expression will generate a really silly sequence of multiple shifts, adds, and comparisons in order to handle negative values correctly. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
--- a/net/netlink/af_netlink.c 2011-12-20 10:25:19.364247598 -0800 +++ b/net/netlink/af_netlink.c 2011-12-20 10:25:46.756570010 -0800 @@ -960,7 +960,7 @@ static int netlink_broadcast_deliver(str skb_set_owner_r(skb, sk); skb_queue_tail(&sk->sk_receive_queue, skb); sk->sk_data_ready(sk, skb->len); - return atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf; + return atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf / 2; } return -1; }
A netlink listening task (such as Quagga/zebra) can easily get overrun when lots of events happen such as a link state transition with full BGP route table. This happens because the sender does not yield to the receiver (unless socket queue is full). The problem is exacerbated because it is typical for listeners to set large receive buffer to attempt to keep up. This patch changes it to yield sooner at halfway instead. Still not a cure-all for listener overrun if listener is slow, but works much reliably. Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html