netdev - Re: [net PATCH v2 2/2] ipv4/GRO: Make GRO conform to RFC 6864

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Message-Id: <20160406.114339.1083222124758102992.davem@davemloft.net>
Date:	Wed, 06 Apr 2016 11:43:39 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	tom@...bertland.com
Cc:	ecree@...arflare.com, herbert@...dor.apana.org.au,
	alexander.duyck@...il.com, aduyck@...antis.com, jesse@...nel.org,
	edumazet@...gle.com, netdev@...r.kernel.org
Subject: Re: [net PATCH v2 2/2] ipv4/GRO: Make GRO conform to RFC 6864

From: Tom Herbert <tom@...bertland.com>
Date: Wed, 6 Apr 2016 10:53:52 -0300

> Packets that are forwarded really should not be GRO'ed in the first
> place because of the loss of information and added latency.

First of all GRO is supposed to be lossless, so please stop saying this
would be a reason to turn it off on a router.

Second of all, the biggest piece of overhead is the routing lookup,
therefore GRO batching helps enormously with routing workloads, and
therefore is appropriate to be enabled on routers.

Yes, I agree that for locally terminated stuff it helps more, but don't
turn this into a "GRO on routers, meh..." type argument.  It simply is
not true at all.