netdev - Re: [patch net-next v5 10/11] tbf: take into account gso skbs

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Message-ID: <20130219164626.GC1506@minipsycho.orion>
Date:	Tue, 19 Feb 2013 17:46:26 +0100
From:	Jiri Pirko <jiri@...nulli.us>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	netdev@...r.kernel.org, davem@...emloft.net, edumazet@...gle.com,
	jhs@...atatu.com, kuznet@....inr.ac.ru, j.vimal@...il.com
Subject: Re: [patch net-next v5 10/11] tbf: take into account gso skbs

Tue, Feb 19, 2013 at 05:15:02PM CET, eric.dumazet@...il.com wrote:
>On Mon, 2013-02-18 at 10:58 +0100, Jiri Pirko wrote:
>> Sun, Feb 17, 2013 at 06:54:23PM CET, eric.dumazet@...il.com wrote:
>> >On Sun, 2013-02-17 at 17:18 +0100, Jiri Pirko wrote:
>> >
>> >> I'm going through this issue back and front and on the second thought,
>> >> I think this patch might not be so wrong after all.
>> >> 
>> >> "Accumulating" time in ptoks would effectively cause the skb to be sent
>> >> only in case time for whole skb is available (accumulated).
>> >> 
>> >> The re-segmenting will only cause the skb fragments sent in each time frame.
>> >> 
>> >> I can't see how the bigger bursts you are reffering to can happen.
>> >> 
>> >> Or am I missing something?
>> >
>> >Token Bucket Filter doesnt allow to accumulate tokens above a given
>> >threshold. Thats the whole point of the algo.
>> >
>> >After a one hour idle time, you don't want to allow your device sending
>> >a burst exceeding the constraint.
>> 
>> You are right, therefore I said "not so wrong". Let me illustrate my
>> thoughts. Here is a patch:
>> 
>> Subject: [patch net-next RFC] tbf: take into account gso skbs
>> 
>> Ignore max_size check for gso skbs. This check made bigger packets
>> incorrectly dropped. Remove this limitation for gso skbs.
>> 
>> Also for peaks, accumulate time for big gso skbs.
>> 
>> Signed-off-by: Jiri Pirko <jiri@...nulli.us>
>> ---
>
>I am sorry, we can not do this accumulation.
>
>If we are allowed to send 1k per second, we are not allowed to send 10k
>after 10 seconds of idle.
>
>Either we are able to split the GSO packet, and respect the TBF
>constraints, either we must drop it.


That's a shame. Would be easy this way, also applicable to act_police :/

About the gso_segment, do you see any cons doing that on enqueue path
rather than dequeue?

Thanks.
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