[Cake] Long-RTT broken again
toke at toke.dk
Tue Nov 3 06:57:50 EST 2015
Sebastian Moeller <moeller0 at gmx.de> writes:
> Well, I believe one of the next steps needs to be to expose limit to
No, just throwing the problem to user space is not a solution: it's a
cop-out. We need to fix the issues so things actually work, and then
*maybe* expose the value to userspace if there is a real need for it.
Not just go "meh, let userspace sort it out"; that is horrible design.
> which would have Toke allowed his measurements
No, it would not: I'm not trying to test whether we have a qdisc that,
through arcane configuration options, can be made to behave properly.
That already exists in fq_codel+HTB. What we're doing here is trying to
build a no-knobs qdisc here that works well in all the scenarios we can
think of. So let's make sure it does, and then talk about whether a
variable should be exposed *after* we've done proper auto-tuning.
> and would have followed the example of most/all other leaf qdiscs and
> put policy into user space where it arguably belongs…
Packet limit is not policy, it's an implementation detail. If you don't
have the memory to run at 100Mbps / 1 second, then *set those values
lower*. You're not going to achieve it anyway if you don't have the
Same thing with the target parameter, BTW: The fact that we still
haven't got it right is not an argument for exposing it to userspace,
quite the contrary: If we, the experts, can't even get it right, why on
earth would be expect users to?
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