Re: [LARTC] HTB: quantum vs. burst
On Thu, Jan 16, 2003 at 09:28:17PM +0100, Stef Coene wrote: If you want to undestand what's going on, you also have to graph the tokens and ctokens. Oh, I see. The negative values of tokens and ctokens that can be seen frequently are because of the hysteresis setting? Also, I have some trouble understanding the tokens/ctokens example on www.docum.org. First, I would suggest that you add an additional bullet specifying initial conditions more explicitly. I suppose that the burst bucket is filled up when the 200bps transmission starts, am I right? Second, it would be useful to state what ceil the example class has since bursting is limited by ceil as we agreed before. Without knowing the class' ceil it's hard to say at what speed the first burst bytes will be released to the network - which is what the other calculations depend on. I use the ethloop from Devik. It's a very nice think ones you understand how it works. I can send you my scripts and config files if you are intersed (and I think you are :) You bet I am, thanks a lot. :) Indeed. I think I need some sleep :) Indeed, the ceil is respected if you use the burst parameter. It's the parent ceil that's broken. That brings up a question: what happens if the parent, say 1:20, has its own parent, say 1:10, and the 1:10 has already been overlimit. In other words, class 1:10, already transmitting at its ceil speed, has a child 1:20 that breaks its ceil because one or more its own children are bursting. Unevitably, 1:10 is forced above its ceil too, right? If that is the case, the state of being overceil will spread all the way up the class hierarchy to the root class? I had a hard time finding the directory where I stored my files :) But I found it. Now I have to figure out what I wanted to document :) Oh, don't feel pressed, take your time, it's been a long time coming anyway. ;-) pvl ___ LARTC mailing list / [EMAIL PROTECTED] http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
Re: [LARTC] HTB: quantum vs. burst
On Thu, Jan 16, 2003 at 08:05:24PM +0100, Stef Coene wrote: No. I did some tests my self witb burst and cburst. The problem is that it's very difficult to measuer and explain it. You have to believe Devik that it works :) I'm not saying that I don't believe him. ;) However, bursting within complex multilevel hierarchies can bring about a number of rather opaque interactions. If you need to be able to understand this (in other words, to know what you are doing), the basic info from the docs is just not enough. And burst is not made for big bursts like you did. Yeah, I know. I'm not saying this is a realistic scenario. I set it this big just to see it properly in the dumps and graphs. It also helps if you disable HTB_HYSTERESIS in the htb qdisc. See faq page for more info. Take a look at the 1:76's graph if you care - see that depression between 140. and 170. second? It's not there because of lack of demand - 1:77 is still asking for bandwidth. It's probably 1:76 retaliating for being pushed above its ceil between 10. and 40. second. If I understand the docs correctly, the depression should not be there since I *did* set 1:76's burst, too. I was thinking about disabling HTB_HYSTERESIS in hope that doing so would remove this problem but I haven't tried it yet. - back to your example - I'd even dare to say that the class you described wouldn't profit from setting burst at all *unless* there's another class competing for the bandwidth. (If there is a contention, the burst setting will matter.) Can you confirm this? No. If you have a 10kbyte/s link and you have a class with ceil = rate = 5kbyte/s and a big burst/cburst (100.000byte or so), you can measure the burst. The first 100.000 byte will be sended by the burst so it will be sended in 10 second. I just repeated the experiment with the exception that only 1:78 (the one with burst set) was asking for bandwidth (the competing 1:77 was silent) and I'm afraid that I'm not able to see any burst anyway. In my view, burst won't let me break my ceil. However, cburst will. I have some very detailed information about how the burst and cburst from parent and child classes are interacting, but I still have to create a page for it. It also explains how burst and cburst can exists and how the tokens and ctokens are changing when you are using the burst. Maybe something I can do tonight. I will keep you informed. That would be *great*. :-) pvl ___ LARTC mailing list / [EMAIL PROTECTED] http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
