From f9ffcedddba5b2fc5ab16ef08bca55af8be2717e Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Mon, 16 Jun 2008 16:38:33 -0700 Subject: pkt_sched: HTB scheduler, change default hysteresis mode to off. 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 Acked-by: Martin Devera Signed-off-by: David S. Miller --- net/sched/sch_htb.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/sched/sch_htb.c') diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c index 5bc1ed490180..9134f029ee0f 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 -- cgit v1.2.3 From 47083fc0735f5145b72fc31236d07339dc52b908 Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Mon, 16 Jun 2008 16:39:32 -0700 Subject: pkt_sched: Change HTB_HYSTERESIS to a runtime parameter htb_hysteresis. Add a htb_hysteresis parameter to htb_sch.ko and by sysfs magic make it runtime adjustable via /sys/module/sch_htb/parameters/htb_hysteresis mode 640. Signed-off-by: Jesper Dangaard Brouer Acked-by: Martin Devera Signed-off-by: David S. Miller --- net/sched/sch_htb.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) (limited to 'net/sched/sch_htb.c') diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c index 9134f029ee0f..6807c97985a5 100644 --- a/net/sched/sch_htb.c +++ b/net/sched/sch_htb.c @@ -28,6 +28,7 @@ * $Id: sch_htb.c,v 1.25 2003/12/07 11:08:25 devik Exp devik $ */ #include +#include #include #include #include @@ -53,13 +54,17 @@ */ #define HTB_HSIZE 16 /* classid hash size */ -#define HTB_HYSTERESIS 0 /* whether to use mode hysteresis for speedup */ +static int htb_hysteresis __read_mostly = 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 #error "Mismatched sch_htb.c and pkt_sch.h" #endif +/* Module parameter and sysfs export */ +module_param (htb_hysteresis, int, 0640); +MODULE_PARM_DESC(htb_hysteresis, "Hysteresis mode, less CPU load, less accurate"); + /* used internaly to keep status of single class */ enum htb_cmode { HTB_CANT_SEND, /* class can't send and can't borrow */ @@ -462,19 +467,21 @@ static void htb_deactivate_prios(struct htb_sched *q, struct htb_class *cl) htb_remove_class_from_row(q, cl, mask); } -#if HTB_HYSTERESIS static inline long htb_lowater(const struct htb_class *cl) { - return cl->cmode != HTB_CANT_SEND ? -cl->cbuffer : 0; + if (htb_hysteresis) + return cl->cmode != HTB_CANT_SEND ? -cl->cbuffer : 0; + else + return 0; } static inline long htb_hiwater(const struct htb_class *cl) { - return cl->cmode == HTB_CAN_SEND ? -cl->buffer : 0; + if (htb_hysteresis) + return cl->cmode == HTB_CAN_SEND ? -cl->buffer : 0; + else + return 0; } -#else -#define htb_lowater(cl) (0) -#define htb_hiwater(cl) (0) -#endif + /** * htb_class_mode - computes and returns current class mode -- cgit v1.2.3