On Tue, Jun 26, 2018 at 06:28:27PM -0700, Cong Wang wrote: > On Tue, Jun 26, 2018 at 5:39 PM Flavio Leitner <fbl@xxxxxxxxxx> wrote: > > > > On Tue, Jun 26, 2018 at 05:29:51PM -0700, Cong Wang wrote: > > > On Tue, Jun 26, 2018 at 4:33 PM Flavio Leitner <fbl@xxxxxxxxxx> wrote: > > > > > > > > It is still isolated, the sk carries the netns info and it is > > > > orphaned when it re-enters the stack. > > > > > > Then what difference does your patch make? > > > > Don't forget it is fixing two issues. > > Sure. I am only talking about TSQ from the very beginning. > Let me rephrase my above question: > What difference does your patch make to TSQ? It avoids burstiness. > > > Before your patch: > > > veth orphans skb in its xmit > > > > > > After your patch: > > > RX orphans it when re-entering stack (as you claimed, I don't know) > > > > ip_rcv, and equivalents. > > ip_rcv() is L3, we enter a stack from L1. So your above claim is incorrect. :) Maybe you found a problem, could you please point me to where in between L1 to L3 the socket is relevant? > > > And for veth pair: > > > xmit from one side is RX for the other side > > > So, where is the queueing? Where is the buffer bloat? GRO list?? > > > > CPU backlog. > > Yeah, but this is never targeted by TSQ: > > tcp_limit_output_bytes limits the number of bytes on qdisc > or device to reduce artificial RTT/cwnd and reduce bufferbloat. > > which means you have to update Documentation/networking/ip-sysctl.txt > too. How it is never targeted? Whole point is to avoid queueing traffic. Would you be okay if I include this chunk? diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index ce8fbf5aa63c..f4c042be0216 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -733,11 +733,11 @@ tcp_limit_output_bytes - INTEGER Controls TCP Small Queue limit per tcp socket. TCP bulk sender tends to increase packets in flight until it gets losses notifications. With SNDBUF autotuning, this can - result in a large amount of packets queued in qdisc/device - on the local machine, hurting latency of other flows, for - typical pfifo_fast qdiscs. - tcp_limit_output_bytes limits the number of bytes on qdisc - or device to reduce artificial RTT/cwnd and reduce bufferbloat. + result in a large amount of packets queued on the local machine + (e.g.: qdiscs, CPU backlog, or device) hurting latency of other + flows, for typical pfifo_fast qdiscs. tcp_limit_output_bytes + limits the number of bytes on qdisc or device to reduce artificial + RTT/cwnd and reduce bufferbloat. Default: 262144 tcp_challenge_ack_limit - INTEGER -- Flavio -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
