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From: Jesper Dangaard Brouer <jdb@comx.dk>
To: "David S. Miller" <davem@davemloft.net>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	Martin Devera <devik@cdi.cz>
Subject: [PATCH 1/2] HTB scheduler, change default hysteresis mode to off.
Date: Tue, 03 Jun 2008 16:05:07 +0200	[thread overview]
Message-ID: <1212501907.13164.30.camel@localhost.localdomain> (raw)
In-Reply-To: <1212501803.13164.27.camel@localhost.localdomain>


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 <hawk@comx.dk>
---
 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



  reply	other threads:[~2008-06-03 14:31 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-06-03 14:03 [PATCH 0/2] HTB scheduler HTB_HYSTERESIS modifications Jesper Dangaard Brouer
2008-06-03 14:05 ` Jesper Dangaard Brouer [this message]
2008-06-03 14:06 ` [PATCH 2/2] Change HTB_HYSTERESIS to a runtime parameter htb_hysteresis Jesper Dangaard Brouer
2008-06-04 13:05 ` [PATCH 0/2] HTB scheduler HTB_HYSTERESIS modifications Martin Devera
2008-06-04 14:28   ` Jesper Dangaard Brouer
2008-06-04 15:31     ` Martin Devera
2008-06-12 10:01     ` Jesper Dangaard Brouer
2008-06-14  9:18       ` Martin Devera
2008-06-16 23:40         ` David Miller
2008-06-17  1:00           ` Denys Fedoryshchenko

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