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

From: Oleg A. Arkhangelsky <redacted>
Date: Sat, 02 Nov 2013 21:43:56 +0400

30.10.2013, 06:33, "David Miller" [off-list ref]:

quoted

GRO should always win, even on a router, because it decreases the
number of fundamental operations (routing lookups) that the stack
needs to perform.

Yes, unless the case when you're using Linux as IP router which is
forwarding 500K mixed IP (TCP and UDP) flows traffic @ 10-20 Gbit/s.
Then GRO is unnecessarily overhead, cause there's no possibility to
accumulate adequate GRO list in such scenario.

If it's not accumulating, then there really isn't much cost because
the bulk of the code paths are short circuited when the flow IDs do
not match.

We touch these packet headers to forward anyways, and that is the bulk
of the cost.