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openwrt-xburst/package/qos-scripts/files/usr/lib/qos/tcrules.awk
nbd cbddbcdae4 qos-scripts update:
- rewrite the RED qdisc calculations and add some comments
this should fix the warnings about bursting (should also fix quirks with various linespeed settings)
- reduce the calculated overhead for upstream, while i'm at it...


git-svn-id: svn://svn.openwrt.org/openwrt/trunk@7782 3c298f89-4303-0410-b956-a3cf2f4a3e73
2007-06-30 02:34:03 +00:00

124 lines
3.0 KiB
Awk

BEGIN {
dmax=100
if (!(linespeed > 0)) linespeed = 128
FS=":"
n = 0
}
($1 != "") {
n++
class[n] = $1
prio[n] = $2
avgrate[n] = ($3 * linespeed / 100)
pktsize[n] = $4
delay[n] = $5
maxrate[n] = ($6 * linespeed / 100)
}
END {
allocated = 0
maxdelay = 0
for (i = 1; i <= n; i++) {
# set defaults
if (!(pktsize[i] > 0)) pktsize[i] = 1500
if (!(prio[i] > 0)) prio[i] = 1
allocated += avgrate[i]
sum_prio += prio[i]
if ((avgrate[i] > 0) && !(delay[i] > 0)) {
sum_rtprio += prio[i]
}
}
# allocation of m1 in rt classes:
# sum(d * m1) must not exceed dmax * (linespeed - allocated)
dmax = 0
for (i = 1; i <= n; i++) {
if (avgrate[i] > 0) {
rtm2[i] = avgrate[i]
if (delay[i] > 0) {
d[i] = delay[i]
} else {
d[i] = 2 * pktsize[i] * 1000 / (linespeed * 1024)
if (d[i] > dmax) dmax = d[i]
}
}
}
ds_avail = dmax * (linespeed - allocated)
for (i = 1; i <= n; i++) {
lsm1[i] = 0
rtm1[i] = 0
lsm2[i] = linespeed * prio[i] / sum_prio
if ((avgrate[i] > 0) && (d[i] > 0)) {
if (!(delay[i] > 0)) {
ds = ds_avail * prio[i] / sum_rtprio
ds_avail -= ds
rtm1[i] = rtm2[i] + ds/d[i]
}
lsm1[i] = rtm1[i]
}
else {
d[i] = 0
}
}
# main qdisc
for (i = 1; i <= n; i++) {
printf "tc class add dev "device" parent 1:1 classid 1:"class[i]"0 hfsc"
if (rtm1[i] > 0) {
printf " rt m1 " int(rtm1[i]) "kbit d " int(d[i] * 1000) "us m2 " int(rtm2[i])"kbit"
}
printf " ls m1 " int(lsm1[i]) "kbit d " int(d[i] * 1000) "us m2 " int(lsm2[i]) "kbit"
print " ul rate " int(maxrate[i]) "kbit"
}
# leaf qdisc
avpkt = 1200
for (i = 1; i <= n; i++) {
printf "tc qdisc add dev "device" parent 1:"class[i]"0 handle "class[i]"00: "
# RED parameters - also used to determine the queue length for sfq
# calculate min value. for links <= 256 kbit, we use 1500 bytes
# use 50 ms queue length as min threshold for faster links
# max threshold is fixed to 3*min
base_pkt=3000
base_rate=256
min_lat=50
if (maxrate[i] <= base_rate) min = base_pkt
else min = int(maxrate[i] * 1024 / 8 * 0.05)
max = 3 * min
limit = (min + max) * 3
if (rtm1[i] > 0) {
# rt class - use sfq
print "sfq perturb 2 limit " limit
} else {
# non-rt class - use RED
avpkt = pktsize[i]
# don't use avpkt values less than 500 bytes
if (avpkt < 500) avpkt = 500
# if avpkt is too close to min, scale down avpkt to allow proper bursting
if (avpkt > min * 0.70) avpkt *= 0.70
# according to http://www.cs.unc.edu/~jeffay/papers/IEEE-ToN-01.pdf a drop
# probability somewhere between 0.1 and 0.2 should be a good tradeoff
# between link utilization and response time (0.1: response; 0.2: utilization)
prob="0.12"
rburst=int((2*min + max) / (3 * avpkt))
if (rburst < 2) rburst = 2
print "red min " min " max " max " burst " rburst " avpkt " avpkt " limit " limit " probability " prob " ecn"
}
}
# filter rule
for (i = 1; i <= n; i++) {
print "tc filter add dev "device" parent 1: prio "class[i]" protocol ip handle "class[i]" fw flowid 1:"class[i] "0"
}
}