net_sched: restore "linklayer atm" handling
Subsystems (3)
PATCH 1/1 net_sched: restore "linklayer atm" handling
commit 56b765b79 ("htb: improved accuracy at high rates") broke the "linklayer atm" handling.
tc class add ... htb rate X ceil Y linklayer atm
The linklayer setting is implemented by modifying the rate table which is send to the kernel. No direct parameter were transferred to the kernel indicating the linklayer setting.
The commit 56b765b79 ("htb: improved accuracy at high rates") removed the use of the rate table system.
To keep compatible with older iproute2 utils, this patch detects the linklayer by parsing the rate table. It also supports future versions of iproute2 to send this linklayer parameter to the kernel directly. This is done by using the __reserved field in struct tc_ratespec, to convey the choosen linklayer option, but only using the lower 4 bits of this field.
Linklayer detection is limited to speeds below 100Mbit/s, because at high rates the rtab is gets too inaccurate, so bad that several fields contain the same values, this resembling the ATM detect. Fields even start to contain "0" time to send, e.g. at 1000Mbit/s sending a 96 bytes packet cost "0", thus the rtab have been more broken than we first realized.
---
include/net/sch_generic.h | 9 ++++++++- include/uapi/linux/pkt_sched.h | 10 +++++++++- net/sched/sch_api.c | 41 ++++++++++++++++++++++++++++++++++++++++ net/sched/sch_generic.c | 1 + net/sched/sch_htb.c | 13 +++++++++++++ 5 files changed, 72 insertions(+), 2 deletions(-)
include/net/sch_generic.h +8 -1
@@ -683,13 +683,19 @@ struct psched_ratecfg {u64 rate_bytes_ps;/* bytes per second */ u32 mult;u16 overhead; +u8 linklayer;u8 shift; };static inline u64 psched_l2t_ns (const struct psched_ratecfg *r,unsigned int len) { -return ((u64)(len + r->overhead) * r->mult) >> r->shift; + len += r->overhead; + +if (unlikely (r->linklayer ==TC_LINKLAYER_ATM )) +return ((u64)(DIV_ROUND_UP (len,48 )*53 ) * r->mult) >> r->shift; + +return ((u64 )len * r->mult) >> r->shift; }extern void psched_ratecfg_precompute (struct psched_ratecfg *r,const struct tc_ratespec *conf);
@@ -700,6 +706,7 @@ static inline void psched_ratecfg_getrate(struct tc_ratespec *res,memset (res,0 ,sizeof (*res)); res->rate = r->rate_bytes_ps; res->overhead = r->overhead; + res->linklayer = (r->linklayer & TC_LINKLAYER_MASK); }#endif
include/uapi/linux/pkt_sched.h +9 -1
@@ -73,9 +73,17 @@ struct tc_estimator {#define TC_H_ROOT (0xFFFFFFFFU)#define TC_H_INGRESS (0xFFFFFFF1U) +/* Need to corrospond to iproute2 tc/tc_core.h "enum link_layer" */ +enum tc_link_layer { +TC_LINKLAYER_UNAWARE ,/* Indicate unaware old iproute2 util */ +TC_LINKLAYER_ETHERNET , +TC_LINKLAYER_ATM , +}; +#define TC_LINKLAYER_MASK 0x0F/* limit use to lower 4 bits */ +struct tc_ratespec {unsigned char cell_log; -unsigned char __reserved; +__u8 linklayer;/* lower 4 bits */ unsigned short overhead;short cell_align;unsigned short mpu;
net/sched/sch_api.c +41 -0
53 lines not on this page · raw message
net/sched/sch_generic.c +1 -0
@@ -909,6 +909,7 @@ void psched_ratecfg_precompute(struct psched_ratecfg *r,memset (r,0 ,sizeof (*r)); r->overhead = conf->overhead; r->rate_bytes_ps = conf->rate; + r->linklayer = (conf->linklayer &TC_LINKLAYER_MASK ); r->mult =1 ;/* * The deal here is to replace a divide by a reciprocal one
net/sched/sch_htb.c +13 -0
@@ -1329,6 +1329,7 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,struct htb_sched *q =qdisc_priv (sch);struct htb_class *cl = (struct htb_class *)*arg, *parent;struct nlattr *opt = tca[TCA_OPTIONS ]; +struct qdisc_rate_table *rtab =NULL , *ctab =NULL ;struct nlattr *tb[TCA_HTB_MAX +1 ];struct tc_htb_opt *hopt;
@@ -1350,6 +1351,18 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,if (!hopt->rate.rate || !hopt->ceil.rate) goto failure; +/* Keeping backward compatible with rate_table based iproute2 tc */ +if (hopt->rate.linklayer ==TC_LINKLAYER_UNAWARE ) { + rtab =qdisc_get_rtab (&hopt->rate, tb[TCA_HTB_RTAB ]); +if (rtab) +qdisc_put_rtab (rtab); + } +if (hopt->ceil.linklayer ==TC_LINKLAYER_UNAWARE ) { + ctab =qdisc_get_rtab (&hopt->ceil, tb[TCA_HTB_CTAB ]); +if (ctab) +qdisc_put_rtab (ctab); + } +if (!cl) {/* new class */ struct Qdisc *new_q;int prio;
From: Jesper Dangaard Brouer <[email protected]>
Date: Wed, 14 Aug 2013 23:47:11 +0200
Quoted 19 lines
commit
56b765b79("htb: improved accuracy at high rates") broke the "linklayer atm" handling.tc class add ... htb rate X ceil Y linklayer atm
The linklayer setting is implemented by modifying the rate table which is send to the kernel. No direct parameter were transferred to the kernel indicating the linklayer setting.
The commit
56b765b79("htb: improved accuracy at high rates") removed the use of the rate table system.To keep compatible with older iproute2 utils, this patch detects the linklayer by parsing the rate table. It also supports future versions of iproute2 to send this linklayer parameter to the kernel directly. This is done by using the
__reservedfield in structtc_ratespec, to convey the choosen linklayer option, but only using the lower 4 bits of this field.
Quoted 8 lines
Linklayer detection is limited to speeds below 100Mbit/s, because at high rates the rtab is gets too inaccurate, so bad that several fields contain the same values, this resembling the ATM detect. Fields even start to contain "0" time to send, e.g. at 1000Mbit/s sending a 96 bytes packet cost "0", thus the rtab have been more broken than we first realized.
Signed-off-by Jesper Dangaard Brouer <[email protected]>
Applied, thanks.