[Codel] [PATCH v5] pkt_sched: codel: Controlled Delay AQM

[Eric Dumazet]

On Sat, 2012-05-05 at 09:11 -0700, Dave Taht wrote:
> Nice!
> 
> Nits:
> 
> 0) I figure you already have an iproute2 patch that you can send?
>     I thought 5 hours ago I had almost, but not entirely grokked netlink.
>     The way you just did it was not at all how I thought it worked. :/
>     but I will read.


I'll send it ( I am currently with friends ...), but you dont need it to
use codel with default params :

qdisc add dev $DEV parent 1:1 handle 10: est 1sec 4sec codel

> 1) I take it if a limit is not specified or set here, sch->limit comes
> from txqueuelen?

No, you set a default limit of 1000 in your patch

>     I do kind of like infinite queues (and angels dancing on the heads of pins)
> 2) I woke up with a mod that could do ecn. I'll do an rfc patch

Not sure it can play, if all packets are ECN, you need to drop at some
point.

> .
> 3) Tom's already on the list
ok
> 4) I'd like to play with this a lot (and have others do so too) before
> it goes upstream,
>     gain kathie and vans blessing, etc. Couple weeks? (see 2). In
> particular I was
>     hoping to see actual pings under load match the target setting.
> I'll get this
>     going on two boxes and see what happens... play with bql, htb, etc...

Hey, you'll send the patch when ready.

> 5) thought the * 16 could be efficiently implemented by the compiler,
> and saves a mem
>     access.

Well, just see the code on x86_32, the ktime conversion is expensive.
Access to memory is free since cache line is already in cpu cache.

By the way, I found the precalculated array of 64 values is not really
useful, we have q->count > 64 most of the time with 2 flows.

> 6) unless 2) happens we can kill q->flags

Yes