[Cake] More on 'target' corner cases - rate/target/interval confusion?

Kevin Darbyshire-Bryant kevin at darbyshire-bryant.me.uk
Thu Nov 5 11:41:56 EST 2015

On 03/11/15 14:12, Toke Høiland-Jørgensen wrote:
> Kevin Darbyshire-Bryant <kevin at darbyshire-bryant.me.uk> writes:
>> At the moment cake is effectively saying that it expects stuff in tin
>> 4 to take 4 times as long to send/its packets are 4 times as big
>> depending which warped view you care to take :-)
> Yup, exactly. However that can be true because tin 4 is shaped to 1/4
> the rate; so for 1 packet, that is actually true.
> However, it's not really a shaping, it's a threshold. Or is it? As I
> said, I need to go read the code :P
> -Toke

Following this up:  The existing code is correct, or is certainly much
more correct than some changes I've been experimenting with :-) The
bottom line is that passing the true 'line' rate and hence related
target/intervals for each tin rather breaks the class/tin shaper,
something I proved with the aid of flent.  'b->tin_rate_bps  = rate;' is
really a reporting construct and isn't actually used as an active part
of code.

So I'm gradually understanding things....by breaking them and putting
them back together :-)   The exact mechanism for shaping eludes me at
the moment (I suspect 'threshold') and quite what effect 'target' and
'interval' really have again is something to experiment with.


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