lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Mon, 03 Feb 2014 09:28:23 -0800 From: Eric Dumazet <eric.dumazet@...il.com> To: Greg Kuperman <gregk@....EDU> Cc: netdev <netdev@...r.kernel.org> Subject: Re: Requeues and ECN marking On Mon, 2014-02-03 at 09:50 -0500, Greg Kuperman wrote: > Hi all, > > I am testing a new congestion control protocol that relies on explicit > congestion notifications (ECN) to notify the receiver of a congestion > event. I have a rate limited link of 1 Mbps, and I am using the RED > queuing discipline with ECN enabled. What I have noticed is that no > matter how small I set my queue size, or how low I set my minimum > marking level, the first ECN marked packet does not get sent out for > about 10 seconds after the input rate exceeds the output rate. Further > examination shows that ECN marking does not occur until the number or > requeues hits 1000. Below are two queries of tc -s -d qdisc ls dev > eth1. > > qdisc red 8028: root refcnt 2 limit 10000000b min 1b max 0b ecn ewma > 30 Plog 21 Scell_log 31 > Sent 1307892 bytes 1247 pkt (dropped 0, overlimits 0 requeues 960) > backlog 1052118b 962p requeues 960 > marked 0 early 0 pdrop 0 other 0 > > qdisc red 8028: root refcnt 2 limit 10000000b min 1b max 0b ecn ewma > 30 Plog 21 Scell_log 31 > Sent 1379262 bytes 1312 pkt (dropped 0, overlimits 72 requeues 1024) > backlog 1122468b 1027p requeues 1024 > marked 72 early 0 pdrop 0 other 0 > > > The txqueuelen defaults to 1000 for the interface, so I figured that > packets maybe buffering there, and then dequeuing, before any packets > are marked. I set txqueuelen to lower values (all the way down to 1), > but the exact same behavior occurs (no marked packets until number of > dequeues hits 1000). In contrast, if I set txqueuele to something very > high, I get no requeues, drops, or marked packets. > > My goal is for packets to be marked as soon as the ingress rate > exceeds the egress. Am I correct in thinking that the requeuing > operation is the culprit? Can I eliminate requeues? Is there something > else I can do to get the behavior I am looking for? > > Thank you all for the help. And please cc me in your replies; I'm not > 100% sure if I get all the messages from this mailing list. requeues have nothing to do with ECN marking. How is done your rate limiting ? Post the whole setup, not part of it, it will help to spot the problem in one go, instead of many mail exchanges. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists