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qos-scripts: replace sfq/red with fq_codel - massively improves latency under load

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SVN-Revision: 31759
This commit is contained in:
Felix Fietkau
2012-05-16 15:23:16 +00:00
parent 3f97b9eb36
commit d5fc598d62
2 changed files with 3 additions and 42 deletions
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3
package/qos-scripts/files/usr/lib/qos/generate.sh
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@@ -344,8 +344,7 @@ tc filter add dev $device parent ffff: protocol ip prio 1 u32 match u32 0 0 flow
fi
add_insmod cls_fw
add_insmod sch_hfsc
add_insmod sch_sfq
add_insmod sch_red
add_insmod sch_fq_codel
cat <<EOF
${INSMOD:+$INSMOD$N}${dev_up:+$dev_up

40
package/qos-scripts/files/usr/lib/qos/tcrules.awk
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@@ -79,45 +79,7 @@ END {
# 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 (qdisc[i] != "") {
# user specified qdisc
print qdisc[i] " limit " limit
} else 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"
}
print "tc qdisc add dev "device" parent 1:"class[i]"0 handle "class[i]"00: fq_codel"
}
# filter rule