pktsize[n] = $4
delay[n] = $5
maxrate[n] = ($6 * linespeed / 100)
+ qdisc[n] = $7
+ filter[n] = $8
}
END {
# leaf qdisc
avpkt = 1200
for (i = 1; i <= n; i++) {
- ql = int((avgrate[i] + linespeed) * 1024 / (8 * pktsize[i]))
printf "tc qdisc add dev "device" parent 1:"class[i]"0 handle "class[i]"00: "
- if (rtm1[i] > 0) {
+
+ # 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 (qdisc[i] != "") {
+ # user specified qdisc
+ print qdisc[i] " limit " limit
+ } else if (rtm1[i] > 0) {
# rt class - use sfq
- print "sfq perturb 2 limit " ql
+ print "sfq perturb 2 limit " limit
} else {
- # non-rt class - use red
- min = int(maxrate[i] * 1024 / 8 * 0.05)
- if (min < avpkt) min = avpkt
- dqb = 8 * min;
- max = int(2.1*min)
- rburst = int((1.5*min + max) / (3 * avpkt))
- print "red min " min " max " max " burst " rburst " avpkt " avpkt " limit " dqb " probability 0.04 ecn"
+ # 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"
+ print "tc filter add dev "device" parent 1: prio "class[i]" protocol ip handle "class[i]"/0xff fw flowid 1:"class[i] "0"
+ filterc=1
+ if (filter[i] != "") {
+ print " tc filter add dev "device" parent "class[i]"00: handle "filterc"0 "filter[i]
+ filterc=filterc+1
+ }
}
}