[LARTC] HFSC again.

[LARTC] HFSC again.

[George Alexandru Dragoi]

       Hello list,

I am now using hfsc for QOS. I have something like this:

tc qdisc add dev ethx root handle 1: hfsc default 9
tc class add dev ethx parent 1: classid 1:1 hfsc ls m2 70mbit ul m2 70mbit

tc class add dev ethx parent 1:1 classid 1:9 hfsc ls m2 7mbit

#DNS stuff follows
tc class add dev ethx parent 1:1 classid 1:2 hfsc rt m1 12mbit d 1ms m2 1mbit

#Half-life
tc class add dev ethx parent 1:1 classid 1:3 hfsc rt m1 24mbit d 1ms m2 2mbit

#Some packets with important flags like SYN SYN,ACK small ACKs
tc class add dev ethx parent 1:1 classid 1:4 hfsc rt m1 12mbit d 1ms m2 1mbit

#www traffic
tc class add dev ethx parent 1:1 classid 1:5 hfsc ls m2 20mbit

#for every client i do this
tc class add dev ethx parent 1:5 classid 1:$wwwclient hfsc rt m2
128kbit ls m2 128kbit
.... And so on for everybody...

#bulk traffic
tc class add dev ethx parent 1:1 classid 1:6 hfsc ls m2 30mbit

#for every client i have ...
tc class add dev ethx parent 1:6 classid 1:$bulkclient ls m2 128kbit
... so on for everybody...


This setup works ok, but unfortunately with not enough knowledge about
what i am doing. The rt classes are meant to guarantee a bandwidth at
an rate (m2). I also used m1 and d parameter, but without thinking
what they really do. After reading
http://www.tik.ee.ethz.ch/~crossbow/rp/plugins/hfsc.html I can say m1
and d has nothing to do with m2 (m1 is calculated based on that
formula), unlike the way i did that, using d as 1ms and m1 as 12 times
greater than m2. After saying those, i have some questions, hopefully
the'll clarify most of my wanders regarding HFSC:

1. How m1 and d really behave, should they be considered and
calculated based on the formula from the link above? Or is just a way
to define how the speed increase or decrease from m1 to m2 and
viceversa into a periodic function (with d as the T).
2. How m1 and d behave when used in different service courves types
(ls, rt and ul).
3. If i use both rt and ls parametters, is ls used for the remained
bandwidth? (i guess Yes)
4. Is it ok to consider the default class as i would do with HTB? I
mean, i usually make the default class in HTB very small and if i see
it does pretty much traffic, then there is something wrong. In HFSC
many exemples gives 10% of bandwidth to default class.
5. In my setup, does classes from bulk traffic will ever get the
maximum of the "most" parent class (70mbit)?

Thanks in advance.
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