Re: [LARTC] English translation of article on HFSC

[Andy Furniss <lists@andyfurniss.entadsl.com>]

Martin A. Brown wrote:
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> Greetings all,
> 
> Working in concert with the original authors, Klaus Rechert and 
> Patrick McHardy, I have translated their article "HFSC Scheduling 
> mit Linux" [0] on Hierarchical Fair Service Curve (HFSC) into 
> English [1].

Thanks Martin.

> 
>    http://linux-ip.net/tc/hfsc.en/

I don't claim to totally get hfsc and don't actually use it yet because 
until recently I only had 288kbit upstream at atm level, which doesn't 
leave enough to split 4/5 users equally. I have 448 now so will use it 
soon, especially if there is going to be a proper atm overhead accounting.

I did in the past test a 4/5 way equal user setup and what I saw makes 
me curious why all the classes in the example are sc.

 From the tests I did the nice thing about hfsc is that you can have 5 
backlogged ls classes and still only add jitter from the transmit time 
of one mtu packet. HTB will add 5x in this case but it's jitter and you 
can skew the average a bit.

5 backlogged/near rate rt with MTU sized packets = 5x jitter with hfsc 
so rt really needs to be uses carefully ?

Of course I havent re tested - it may have been because the ls each had 
very small rates but could borrow.

Andy.
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