netdev - Re: [net-next PATCH] dql: add a burst attribute

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Message-ID: <1412086646.30721.81.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Tue, 30 Sep 2014 07:17:26 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Florian Westphal <fw@...len.de>
Cc:	Jesper Dangaard Brouer <brouer@...hat.com>, netdev@...r.kernel.org,
	"David S. Miller" <davem@...emloft.net>,
	Tom Herbert <therbert@...gle.com>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	Daniel Borkmann <dborkman@...hat.com>,
	Jamal Hadi Salim <jhs@...atatu.com>,
	Alexander Duyck <alexander.duyck@...il.com>,
	John Fastabend <john.r.fastabend@...el.com>,
	Dave Taht <dave.taht@...il.com>, toke@...e.dk
Subject: Re: [net-next PATCH] dql: add a burst attribute

On Tue, 2014-09-30 at 15:46 +0200, Florian Westphal wrote:
> Eric Dumazet <eric.dumazet@...il.com> wrote:
> > From: Eric Dumazet <edumazet@...gle.com>
> > 
> > Add a new dql attribute, to control how much packets we are allowed to
> > burst from qdisc to device.
> 
> I understand the motivation for this, but I find it a bit out-of-place
> to have a 'packet' type counter in bql context?
> 
> Would it perhaps make more sense to restrict bulk dequeues by an upper
> (possibly changeable from userspace) byte counter limit?

The byte count is already provided : its the BQL limit.
We already have ways to tune it (limit_min & limit_max)
We do not think we need something else here.
That was the whole point of reusing BQL in the first place : Its already
powerful and implemented.

This new attribute is a packet burst.


When I suggested 'pburst' attribute for pktgen to Alexei, he sent a
patch with "burst". Nobody complained.

Now I am reusing what apparently was OK for pktgen, you seem to object.

If you feel not comfortable with "burst", rename it to whatever you
think is best.

But please, do not hard code magic 7 in your code.

Thanks


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