netdev - Re: Quota in __qdisc

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Message-Id: <20141007.131938.1410434352331637585.davem@davemloft.net>
Date:	Tue, 07 Oct 2014 13:19:38 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	eric.dumazet@...il.com
Cc:	hannes@...essinduktion.org, brouer@...hat.com,
	netdev@...r.kernel.org, therbert@...gle.com, fw@...len.de,
	dborkman@...hat.com, jhs@...atatu.com, alexander.duyck@...il.com,
	john.r.fastabend@...el.com, dave.taht@...il.com, toke@...e.dk
Subject: Re: Quota in __qdisc_run()

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Tue, 07 Oct 2014 08:01:20 -0700

> On Tue, 2014-10-07 at 16:43 +0200, Hannes Frederic Sowa wrote:
> 
>> This needs to be:
>> 
>> do
>>    ...
>> while ((iskb = iskb->next))
> 
> I do not feel needed to break the bulk dequeue at precise quota
> boundary. These quotas are advisory, and bql prefers to get its full
> budget for appropriate feedback from TX completion.
> 
> Quota was a packet quota, which was quite irrelevant if segmentation had
> to be done, so I would just let the dequeue be done so that we benefit
> from optimal xmit_more.

Yes, this makes sense, do a full qdisc_restart() cycle without boundaries,
then check how much quota was used afterwards to guard the outermost loop.
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