Re: HTB vs CoDel performance

On Tue, Sep 18, 2012 at 5:45 PM, Eric Dumazet [off-list ref] wrote:

On Tue, 2012-09-18 at 17:28 +0800, Lin Ming wrote:

quoted

Hi,

I'm testing htb performance on a gigabit router running 2.6.32 kernel.
Packet path: PC1 ---> Router LAN port ---> Router WAN port ---> PC2

pfifo_fast: 920Mbps
htb: 750Mbps, ~20% drops compared to pfifo_fast

htb tc commands as below,
# tc qdisc add dev eth10 root handle 20: htb default 1
# tc class add dev eth10 parent 20 classid 20:1 htb prio 2 rate
1024Mbit ceil 1024Mbit burst 1281408b cburst 1281408b

The performance drop seems caused by the complex htb enqueue/dequeue algorithm.

I had a quick look at CoDel code, seems it does not have so complex
data structure as HTB.
I'm going to backport CoDel. Is this a good choice?
Can I gain similar performance as pfifo_fast?

codel is quite different than HTB : It has no rate control, so its very
fast. (But it has no prio differentiation as pfifo_fast with its 3
bands)

So what are your exact needs ?

I need traffic priority/traffic shaping/rate control ... actually all
QoS features on the router.
And if I just set the rate to gigabit(no other settings), for example,

# tc qdisc add dev eth10 root handle 20: htb default 1
# tc class add dev eth10 parent 20 classid 20:1 htb prio 2 rate
1024Mbit ceil 1024Mbit burst 1281408b cburst 1281408b

it should gain similar performance as pfifo_fast.

codel has no rate control. So seems I have to find way to optimize htb?