[Codel] [Bloat] Exploring the potential of codel, fq_codel, and qfq

Jonathan Morton chromatix99 at gmail.com
Wed May 16 05:02:37 EDT 2012


With FQ, I don't see what that would buy you. 

The key to knowledge is not to rely on others to teach you it. 

On 16 May 2012, at 11:17, Eric Dumazet <eric.dumazet at gmail.com> wrote:

> On Wed, 2012-05-16 at 09:47 +0200, Eric Dumazet wrote:
> 
>> On TCP_RR pure workload, you have one packet in flight per flow.
>> 
>> ECN adds nothing in this case, only that no 'drops' occurs at all.
>> 
>> It might be good to change fq_codel to perform ECN mark only if flow
>> queue has more packets.
>> 
>> If not, plain drop.
> 
> And for codel, if all packets are ECN enabled, there is no 'drop' on a
> pure TCP_RR workload, you endup codel downgraded to pfifo
> 
> An idea would be following :
> 
> If sojourn_time is above a new limit (say ecn_threshold), drop packet no
> matter it is ECN capable or not.
> 
> This still gives incentive to ECN flows, but allow drops in case all
> flows are ECN.
> 
> target = 5ms ;
> ecn_threshold = target * 2;
> interval = 100ms;
> 
> 
> 
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