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Hello.
I am wondering if the default (auto-computed) burst
and cburst parameters are appropriate values for my
application.
I have a 100 mbit interface which is connected to a
16 mbit uplink.
I am sharing this bandwidth into a set of
partitions (tc classes) defined as follows:
root class [1:1]
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part-1
[1:20] part-2
[1:30]
part-3 [1:40]
My script (without filter statements)
follows:
[root@mercury ~]# cat tc.sh
#!/bin/bash
# reset
tc qdisc del dev eth0 root
# root qdisc
tc qdisc add dev eth0 root handle 1: htb default
10
# root class
tc class add dev eth0 parent 1: classid 1:1 htb
rate 16mbit
# default partition
tc class add dev eth0 parent 1:1 classid 1:10 htb
rate 1mbit ceil 16mbit
tc qdisc add dev eth0 parent 1:10 handle 10: sfq
perturb 10
# partition-1
tc class add dev eth0 parent 1:1 classid 1:20 htb
rate 1mbit ceil 1mbit
tc qdisc add dev eth0 parent 1:20 handle 20: sfq
perturb 10
# partition-2
tc class add dev eth0 parent 1:1 classid 1:30 htb
rate 256kbit ceil 256kbit
tc qdisc add dev eth0 parent 1:30 handle 30: sfq
perturb 10
# partition-3
tc class add dev eth0 parent 1:1 classid 1:40 htb
rate 128kbit ceil 128kbit
tc qdisc add dev eth0 parent 1:40 handle 40: sfq
perturb 10
A sample from tc -s show class dev eth0 is:
[root@mercury ~]# tc -s class show dev eth0
class htb 1:1 root rate 16Mbit ceil 16Mbit burst 3598b cburst 3598b Sent 238 bytes 3 pkts (dropped 0, overlimits 0 requeues 0) lended: 0 borrowed: 0 giants: 0 tokens: 1794 ctokens: 1794 class htb 1:10 parent 1:1 leaf 10: prio 0 rate 1Mbit ceil 16Mbit burst
1724b cburst 3598b
Sent 238 bytes 3 pkts (dropped 0, overlimits 0 requeues 0) lended: 3 borrowed: 0 giants: 0 tokens: 13345 ctokens: 1794 class htb 1:20 parent 1:1 leaf 20: prio 0 rate 1Mbit ceil 1Mbit burst 1724b
cburst 1724b
Sent 0 bytes 0 pkts (dropped 0, overlimits 0 requeues 0) lended: 0 borrowed: 0 giants: 0 tokens: 14131 ctokens: 14131 class htb 1:30 parent 1:1 leaf 30: prio 0 rate 256Kbit ceil 256Kbit burst
1631b cburst 1631b
Sent 0 bytes 0 pkts (dropped 0, overlimits 0 requeues 0) lended: 0 borrowed: 0 giants: 0 tokens: 52224 ctokens: 52224 class htb 1:40 parent 1:1 leaf 40: prio 0 rate 128Kbit ceil 128Kbit burst
1615b cburst 1615b
Sent 0 bytes 0 pkts (dropped 0, overlimits 0 requeues 0) lended: 0 borrowed: 0 giants: 0 tokens: 103424 ctokens: 103424 I am also graphing the 'Sent' bytes value as reported above and I noticed
that the classes usually exceed the configured rates slightly.
Can be be improved by tuning the burst and/or cburst values?
Note that MTU is set to 1500 bytes.
Regards,
Charles |
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