From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: RED tc qdisc not dropping? Date: Wed, 03 Oct 2012 23:12:46 +0200 Message-ID: <1349298766.10199.5.camel@edumazet-glaptop> References: <986427880.11879793.1349295290592.JavaMail.root@cds046> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: Ken Savage Return-path: Received: from mail-bk0-f46.google.com ([209.85.214.46]:48272 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755369Ab2JCVMv (ORCPT ); Wed, 3 Oct 2012 17:12:51 -0400 Received: by bkcjk13 with SMTP id jk13so6397673bkc.19 for ; Wed, 03 Oct 2012 14:12:50 -0700 (PDT) In-Reply-To: <986427880.11879793.1349295290592.JavaMail.root@cds046> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 2012-10-03 at 14:14 -0600, Ken Savage wrote: > Hi there, > > I'm running openSUSE 12.2, using the machine as a router/WANsim device. > > Previously, I was running an older CentOS installation with a 2.6 kernel, > and my tc-red commands ran just fine, and imposed some bandwidth constraint > to the packets upon egress. In 3.4.6, this doesn't seem to be the case > any longer. > > Without any restrictions, there would be 25-30Mbps of traffic flowing out > the interface -- this is to give you a sense of the data rate. > > > Now, this said, I did notice that the latest RED code has the 'harddrop' > option that I didn't have under CentOS with kernel 2.6. So in my attempt > to see ANYTHING happening with 3.4.6, I entered: > > tc qdisc add dev eth0 root red limit 40000 min 3000 max 9000 avpkt 1000 burst 5 harddrop probability 1 > > > Issuing 'tc -s -d qdisc show dev eth0', I obtain: > > qdisc red 8006: root refcnt 2 limit 40000b min 3000b max 9000b harddrop ewma 2 probability 0.73242 Scell_log 12 > Sent 254028472 bytes 207494 pkt (dropped 0, overlimits 0 requeues 0) > backlog 0b 0p requeues 0 > marked 0 early 0 pdrop 0 other 0 > > > All those zeroes seem a little amiss to me ;) > Not sure I understand... Why RED should drop a packet if there is no backlog ? if you NIC has Gigabit speed, RED will allow Gigabit speed as well.