On Wed, 15 Apr 2015, Eric Dumazet wrote: > On Wed, 2015-04-15 at 18:23 +0100, George Dunlap wrote: > > > Which means that max(2*skb->truesize, sk->sk_pacing_rate >>10) is > > *already* larger for Xen; that calculation mentioned in the comment is > > *already* doing the right thing. > > Sigh. > > 1ms of traffic at 40Gbit is 5 MBytes > > The reason for the cap to /proc/sys/net/ipv4/tcp_limit_output_bytes is > to provide the limitation of ~2 TSO packets, which _also_ is documented. > > Without this limitation, 5 MBytes could translate to : Fill the queue, > do not limit. > > If a particular driver needs to extend the limit, fine, document it and > take actions.
What actions do you have in mind exactly? It would be great if you could suggest how to move forward from here, beside documentation. I don't think we can really expect every user that spawns a new VM in the cloud to manually echo blah > /proc/sys/net/ipv4/tcp_limit_output_bytes to an init script. I cannot imagine that would work well. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/