Re: [PATCH v4 net-next] net: introduce dev_set_forwarding()

Herbert Xu
2013-11-11T18:58:12Z

On Thu, Nov 07, 2013 at 09:40:12PM -0800, Eric Dumazet wrote:
> On Fri, 2013-11-08 at 13:21 +0800, Herbert Xu wrote:
>
> > My point is that even if you did that GRO with your frag_list
> > patch should still be a win because the stack prior to the qdisc
> > gets run once instead of two or three times.
> >
>
> OK, lets me repeat again.
>
> 64KB packet receive/aggregation time is more than 540 us on 1Gbps link.

I presume you're still talking about the case where we're CPU-
bound on receive. In that case I totally agree that you need to
impose a limit on the NAPI/GRO run so that we don't keep doing GRO
forever.

However, the limit should be based on time and not an arbitrary
number such as MAX_SKB_FRAGS. IOW relying on not having a frag_list
to provide a bound to GRO is just wrong.

Cheers,
--
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
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