Hi,
On Thu, 2006-03-02 at 15:49 +0000, Andy Furniss wrote:
> Russell Stuart wrote:
>
> > The following patch to tc allows it to perform an exact
> > ATM / ADSL rate calculation.
>
> I probably haven't read the patch properly - but I don't think you can
> do it exactly without patching net/sched/sched_htb.c aswell.
> Specifically you need to add overhead - 1 before htb shifts the length
> to get the slot num (-1 because you need to get 48 and 49 payload length
> to map to different slots 47 and 48 do). The table should be filled
> according to this.
As Markus mentioned in another post on this thread, Jesper Dangaard
Brouer (http://www.adsl-optimizer.dk) has already written an iproute2
and Linux kernel patch that implements the above. ATM cell alignment is
done in tc_core.c, and the per packet overhead is passed to the relevant
kernel modules.
I have made some very minor changes to the patches, so that they apply
cleanly to iproute2-20051007 and kernel 2.6.15. You will find them
attached to this mail.
> > When using this command lines, you always specify the ADSL
> > link capacity as quoted by the modem. Eg, if you are
> > controlling incoming traffic on a 512k/128k link, you
> > specify the link speed as 512000bps.
>
> You need to look at the atm user rate shown by your modem, for me in the
> past it was 288/576 this was sold as 250/500 by teleco and 256/512 by isp.
>
> You also need to back off a couple of kbit (egress - ingress more for
> different reasons) - one of my modems does cell qos bases on rate of
> whole cells/sec - don't kmow how common that is. Also if you run exactly
> on the rate and queue formed when starting/restarting scripts it would
> not drain till the traffic stopped.
Setting the MTU to 1478 is probably a good idea to prevent excessive
cell usage. Reasoning behind this being: 1488 is the largest multiple of
48 under 1500, less 2 bytes for the PPP header and 8 for the AAL5
footer.
Perhaps you can confirm this isn't way off the mark Andy? :)
--
Adam James <ad@xxxxxxxxxxxxxxxx>
diff -Naur -p iproute-20051007.orig/include/linux/pkt_sched.h iproute-20051007.overhead/include/linux/pkt_sched.h
--- iproute-20051007.orig/include/linux/pkt_sched.h 2006-02-15 23:04:06.000000000 +0000
+++ iproute-20051007.overhead/include/linux/pkt_sched.h 2006-02-15 23:03:28.000000000 +0000
@@ -82,7 +82,7 @@ struct tc_ratespec
unsigned char cell_log;
unsigned char __reserved;
unsigned short feature;
- short addend;
+ unsigned short overhead;
unsigned short mpu;
__u32 rate;
};
@@ -484,7 +484,7 @@ struct tc_ratespec
unsigned char cell_log;
unsigned char __reserved;
unsigned short feature;
- short addend;
+ unsigned short overhead;
unsigned short mpu;
__u32 rate;
};
diff -Naur -p iproute-20051007.orig/tc/q_htb.c iproute-20051007.overhead/tc/q_htb.c
--- iproute-20051007.orig/tc/q_htb.c 2006-02-15 23:04:06.000000000 +0000
+++ iproute-20051007.overhead/tc/q_htb.c 2006-02-15 23:03:28.000000000 +0000
@@ -350,6 +350,9 @@ static void explain(void)
" mpu minimum packet size used in rate computations\n"
" overhead per-packet size overhead used in rate computations\n"
+ " cell_size used to calculate ATM SAR overhead \n"
+ " cell_payload (SAR = segmentation and reassembly) \n"
+
" ceil definite upper class rate (no borrows) {rate}\n"
" cburst burst but for ceil {computed}\n"
" mtu max packet size we create rate map for {1600}\n"
@@ -416,7 +419,9 @@ static int htb_parse_class_opt(struct qd
unsigned buffer=0,cbuffer=0;
int cell_log=-1,ccell_log = -1;
unsigned mtu, mpu;
- unsigned char mpu8 = 0, overhead = 0;
+ unsigned short cell_size, cell_payload;
+ unsigned char mpu8 = 0;
+ unsigned short overhead = 0;
struct rtattr *tail;
memset(&opt, 0, sizeof(opt)); mtu = 1600; /* eth packet len */
@@ -440,7 +445,7 @@ static int htb_parse_class_opt(struct qd
}
} else if (matches(*argv, "overhead") == 0) {
NEXT_ARG();
- if (get_u8(&overhead, *argv, 10)) {
+ if (get_u16(&overhead, *argv, 10)) {
explain1("overhead"); return -1;
}
} else if (matches(*argv, "quantum") == 0) {
@@ -448,6 +453,16 @@ static int htb_parse_class_opt(struct qd
if (get_u32(&opt.quantum, *argv, 10)) {
explain1("quantum"); return -1;
}
+ } else if (matches(*argv, "cell_size") == 0) {
+ NEXT_ARG();
+ if (get_u16(&cell_size, *argv, 10)) {
+ explain1("cell_size"); return -1;
+ }
+ } else if (matches(*argv, "cell_payload") == 0) {
+ NEXT_ARG();
+ if (get_u16(&cell_payload, *argv, 10)) {
+ explain1("cell_payload"); return -1;
+ }
} else if (matches(*argv, "burst") == 0 ||
strcmp(*argv, "buffer") == 0 ||
strcmp(*argv, "maxburst") == 0) {
@@ -513,10 +528,11 @@ static int htb_parse_class_opt(struct qd
sute that buffer is larger than mtu and to have some safeguard space */
if (!buffer) buffer = opt.rate.rate / get_hz() + mtu;
if (!cbuffer) cbuffer = opt.ceil.rate / get_hz() + mtu;
-
+
+ opt.ceil.mpu = mpu8; opt.rate.mpu = mpu8;
+ opt.ceil.overhead = overhead; opt.rate.overhead = overhead;
/* encode overhead and mpu, 8 bits each, into lower 16 bits */
mpu = (unsigned)mpu8 | (unsigned)overhead << 8;
- opt.ceil.mpu = mpu; opt.rate.mpu = mpu;
if ((cell_log = tc_calc_rtable(opt.rate.rate, rtab, cell_log, mtu, mpu)) < 0) {
fprintf(stderr, "htb: failed to calculate rate table.\n");
@@ -579,8 +595,8 @@ static int htb_print_opt(struct qdisc_ut
fprintf(f, "cburst %s/%u mpu %s overhead %s ",
sprint_size(cbuffer, b1),
1<<hopt->ceil.cell_log,
- sprint_size(hopt->ceil.mpu&0xFF, b2),
- sprint_size((hopt->ceil.mpu>>8)&0xFF, b3));
+ sprint_size(hopt->ceil.mpu, b2),
+ sprint_size(hopt->ceil.overhead, b3));
fprintf(f, "level %d ", (int)hopt->level);
} else {
fprintf(f, "burst %s ", sprint_size(buffer, b1));
diff -Naur -p iproute-20051007.orig/tc/tc_core.c iproute-20051007.overhead/tc/tc_core.c
--- iproute-20051007.orig/tc/tc_core.c 2004-07-30 21:26:15.000000000 +0100
+++ iproute-20051007.overhead/tc/tc_core.c 2006-02-15 23:03:28.000000000 +0000
@@ -42,6 +42,35 @@ unsigned tc_calc_xmittime(unsigned rate,
return tc_core_usec2tick(1000000*((double)size/rate));
}
+#ifndef ATM_CELL_SIZE
+#define ATM_CELL_SIZE 53 /* ATM cell size incl. header */
+#endif
+#ifndef ATM_CELL_PAYLOAD
+#define ATM_CELL_PAYLOAD 48 /* ATM payload size */
+#endif
+
+#define ATM_ALIGN y
+
+/*
+ The align_to_cells is used for determining the (ATM) SAR alignment
+ overhead at the ATM layer. (SAR = Segmentation And Reassembly)
+ This is for example needed when scheduling packet on an ADSL
+ connection. The ATM-AAL overhead should preferably be added in the
+ kernel when doing table lookups (due to precision/alignment of the
+ table), if not the ATM-AAL overhead should be added to the size
+ before calling the function. --Hawk, d.7/11-2004. <hawk@xxxxxxx>
+ */
+unsigned tc_align_to_cells(unsigned size, int cell_size, int cell_payload)
+{
+ int linksize, cells;
+ cells = size / cell_payload;
+ if ((size % cell_payload) > 0) {
+ cells++;
+ }
+ linksize = cells * cell_size;
+ return linksize;
+}
+
/*
rtab[pkt_len>>cell_log] = pkt_xmit_time
*/
@@ -62,11 +91,16 @@ int tc_calc_rtable(unsigned bps, __u32 *
cell_log++;
}
for (i=0; i<256; i++) {
- unsigned sz = (i<<cell_log);
- if (overhead)
- sz += overhead;
+ unsigned sz = ((i+1)<<cell_log);
+ if (overhead) {
+ // Is now done in the kernel (eg. sch_htb.c, func L2T )
+ // sz += overhead;
+ }
if (sz < mpu)
sz = mpu;
+#ifdef ATM_ALIGN
+ sz = tc_align_to_cells(sz, ATM_CELL_SIZE, ATM_CELL_PAYLOAD);
+#endif
rtab[i] = tc_core_usec2tick(1000000*((double)sz/bps));
}
return cell_log;
diff -Naur -p linux-source-2.6.15.orig/include/linux/pkt_sched.h linux-source-2.6.15.overhead/include/linux/pkt_sched.h
--- linux-source-2.6.15.orig/include/linux/pkt_sched.h 2006-01-03 03:21:10.000000000 +0000
+++ linux-source-2.6.15.overhead/include/linux/pkt_sched.h 2006-02-15 16:47:46.000000000 +0000
@@ -78,7 +78,7 @@ struct tc_ratespec
unsigned char cell_log;
unsigned char __reserved;
unsigned short feature;
- short addend;
+ unsigned short overhead;
unsigned short mpu;
__u32 rate;
};
diff -Naur -p linux-source-2.6.15.orig/net/sched/police.c linux-source-2.6.15.overhead/net/sched/police.c
--- linux-source-2.6.15.orig/net/sched/police.c 2006-01-03 03:21:10.000000000 +0000
+++ linux-source-2.6.15.overhead/net/sched/police.c 2006-02-15 16:53:55.000000000 +0000
@@ -33,8 +33,8 @@
#include <net/sock.h>
#include <net/act_api.h>
-#define L2T(p,L) ((p)->R_tab->data[(L)>>(p)->R_tab->rate.cell_log])
-#define L2T_P(p,L) ((p)->P_tab->data[(L)>>(p)->P_tab->rate.cell_log])
+#define L2T(p,L) ((p)->R_tab->data[((L)-1+(p)->R_tab->rate.overhead)>>(p)->R_tab->rate.cell_log])
+#define L2T_P(p,L) ((p)->P_tab->data[((L)-1+(p)->P_tab->rate.overhead)>>(p)->P_tab->rate.cell_log])
#define PRIV(a) ((struct tcf_police *) (a)->priv)
/* use generic hash table */
diff -Naur -p linux-source-2.6.15.orig/net/sched/sch_cbq.c linux-source-2.6.15.overhead/net/sched/sch_cbq.c
--- linux-source-2.6.15.orig/net/sched/sch_cbq.c 2006-01-03 03:21:10.000000000 +0000
+++ linux-source-2.6.15.overhead/net/sched/sch_cbq.c 2006-02-15 16:47:46.000000000 +0000
@@ -193,7 +193,7 @@ struct cbq_sched_data
};
-#define L2T(cl,len) ((cl)->R_tab->data[(len)>>(cl)->R_tab->rate.cell_log])
+#define L2T(cl,len) ((cl)->R_tab->data[((len)-1+(cl)->R_tab->rate.overhead)>>(cl)->R_tab->rate.cell_log])
static __inline__ unsigned cbq_hash(u32 h)
diff -Naur -p linux-source-2.6.15.orig/net/sched/sch_htb.c linux-source-2.6.15.overhead/net/sched/sch_htb.c
--- linux-source-2.6.15.orig/net/sched/sch_htb.c 2006-01-03 03:21:10.000000000 +0000
+++ linux-source-2.6.15.overhead/net/sched/sch_htb.c 2006-02-15 16:47:46.000000000 +0000
@@ -206,7 +206,8 @@ struct htb_class
static __inline__ long L2T(struct htb_class *cl,struct qdisc_rate_table *rate,
int size)
{
- int slot = size >> rate->rate.cell_log;
+ int overhead = rate->rate.overhead;
+ int slot = (size-1+overhead) >> rate->rate.cell_log;
if (slot > 255) {
cl->xstats.giants++;
slot = 255;
diff -Naur -p linux-source-2.6.15.orig/net/sched/sch_tbf.c linux-source-2.6.15.overhead/net/sched/sch_tbf.c
--- linux-source-2.6.15.orig/net/sched/sch_tbf.c 2006-01-03 03:21:10.000000000 +0000
+++ linux-source-2.6.15.overhead/net/sched/sch_tbf.c 2006-02-15 16:47:46.000000000 +0000
@@ -132,8 +132,8 @@ struct tbf_sched_data
struct Qdisc *qdisc; /* Inner qdisc, default - bfifo queue */
};
-#define L2T(q,L) ((q)->R_tab->data[(L)>>(q)->R_tab->rate.cell_log])
-#define L2T_P(q,L) ((q)->P_tab->data[(L)>>(q)->P_tab->rate.cell_log])
+#define L2T(q,L) ((q)->R_tab->data[((L)-1+(q)->R_tab->rate.overhead)>>(q)->R_tab->rate.cell_log])
+#define L2T_P(q,L) ((q)->P_tab->data[((L)-1+(q)->P_tab->rate.overhead)>>(q)->P_tab->rate.cell_log])
static int tbf_enqueue(struct sk_buff *skb, struct Qdisc* sch)
{
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