From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jesper Dangaard Brouer Subject: [PATCH 1/2] HTB scheduler, change default hysteresis mode to off. Date: Tue, 03 Jun 2008 16:05:07 +0200 Message-ID: <1212501907.13164.30.camel@localhost.localdomain> References: <1212501803.13164.27.camel@localhost.localdomain> Reply-To: jdb@comx.dk Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: "netdev@vger.kernel.org" , Martin Devera To: "David S. Miller" Return-path: Received: from lanfw001a.cxnet.dk ([87.72.215.196]:56445 "EHLO lanfw001a.cxnet.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752662AbYFCObN (ORCPT ); Tue, 3 Jun 2008 10:31:13 -0400 In-Reply-To: <1212501803.13164.27.camel@localhost.localdomain> Sender: netdev-owner@vger.kernel.org List-ID: The HTB hysteresis mode reduce the CPU load, but at the cost of scheduling accuracy. On ADSL links (512 kbit/s upstream), this inaccuracy introduce significant jitter, enought to disturbe VoIP. For details see my masters thesis (http://www.adsl-optimizer.dk/thesis/), chapter 7, section 7.3.1, pp 69-70. Signed-off-by: Jesper Dangaard Brouer --- net/sched/sch_htb.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c index 5bc1ed4..9134f02 100644 --- a/net/sched/sch_htb.c +++ b/net/sched/sch_htb.c @@ -53,7 +53,7 @@ */ #define HTB_HSIZE 16 /* classid hash size */ -#define HTB_HYSTERESIS 1 /* whether to use mode hysteresis for speedup */ +#define HTB_HYSTERESIS 0 /* whether to use mode hysteresis for speedup */ #define HTB_VER 0x30011 /* major must be matched with number suplied by TC as version */ #if HTB_VER >> 16 != TC_HTB_PROTOVER -- 1.5.4.2