From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sanket Shah Subject: HFSC link sharing behavior related query Date: Thu, 2 Jul 2009 16:53:40 +0530 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit To: netdev@vger.kernel.org Return-path: Received: from wf-out-1314.google.com ([209.85.200.169]:42291 "EHLO wf-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750940AbZGBLXi (ORCPT ); Thu, 2 Jul 2009 07:23:38 -0400 Received: by wf-out-1314.google.com with SMTP id 26so621307wfd.4 for ; Thu, 02 Jul 2009 04:23:40 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-ID: Hi, We are doing experiments on hfsc in various network scenarios. Some of the results are not as per our expectation/understanding of our hfsc behavior. ----------------------------------------------------------------------------------------------------------------------- Scenario 1: 1: (hfsc qdisc) | | 1:1 (hfsc root class) (rt 0, ls 40, ul 40) | ---------------------------------------------------------------- | | 1:2 (rt 10, ls 1, ul 20) 1:3 (rt 30, ls 1, ul 40) | | 2: (sfq qdisc) 3: (sfq qdisc) In above scenario, 1:2 and 1:3 both are doing http download and we are getting following results. 1:2 - 10 kbps 1:3 - 30 kbps That is as per the expectation. After 5 minutes we are changing ls and ul of 1:1 from 40 to 100. (rt 0, ls 100, ul 100) For first 2 minutes after above change, 1:2 - 20 kbps 1:3 - 80 kbps In this case ul curve is getting violated for 2 mins. After 2 minutes, 1:2 - 20 kbps 1:3 - 50 kbps That is expected. Is it an expected behavior ? why ul curve got violated ? ----------------------------------------------------------------------------------------------------------------------- Scenario 2: 1: (hfsc qdisc) | | 1:1 (hfsc root class) (rt 0, ls 200, ul 200) | ------------------------------------------------------------------------------------------------------------------------- | | | | 1:2 (rt 75, ls 32, ul 200) 1:3 (rt 25, ls 16, ul 200) 1:4(rt 50, ls 8, ul 200) 1:5 (rt 25,ls 128,ul 200) | | | | 2: (sfq qdisc) 3: (sfq qdisc) 4:(sfq qdisc) 5: (sfq qdisc) In above scenario, 1:2, 1:3, 1:4, 1:5 all are doing http download and we are expecting following results, 1:2 - 75 kbps 1:3 - 25 kbps 1:4 - 50 kbps 1:5 - 50 kbps (according to link sharing ratio, excess 25 kbps bandwidth should remain with 1:5) But we are observing that 25 kbps excess bandwidth is floating across 1:2,1:3 and 1:5 on about 4 to 5 minutes. We are also observing few packet drops in 1:2 and 1:3. Is there any relation between link sharing and packet drop ? ----------------------------------------------------------------------------------------------------------------------- Regards, Sanket Shah