Re: [PATCH v2 net-next] net: introduce gro_frag_list_enable sysctl

David Miller
2013-10-30T02:34:57Z

From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Wed, 30 Oct 2013 10:19:06 +0800

> On Tue, Oct 29, 2013 at 07:13:50PM -0700, Jerry Chu wrote:
>> On Tue, Oct 29, 2013 at 7:05 PM, Herbert Xu <herbert@gondor.apana.org.au> wrote:
>>
>> > If we are indeed able to do that, I doubt we would even need
>> > the sysctl patch since the GRO performance should be vastly
>> > superior to the non-GRO case, even for a router/bridge.
>>
>> Probably not the case for the simple forwarding case. See my
>> test result of some small (5-8%) CPU+throughput penalty from
>> GRO (over GRE tunnel) posted previously. But I can believe
>> the number may be very different if the forwarding path involves
>> more work (NAT, iptables filtering,...,etc) resulting in a higher per
>> pkt cost.
>
> Your numbers are with Eric's current patch that just linearises
> the packet, what I'm saying is that you don't need to linearise
> these packets since the packet boundaries are still there, just
> hidden inside each frag_list.

Agreed.