Subject: Re: [0/14] GRO: Lots of microoptimisations

From: Benjamin LaHaise <[email-masked]>
Date: Wed, 27 May 2009 13:52:23 -0400

Hi Herbert,

On Wed, May 27, 2009 at 02:45:39PM +1000, Herbert Xu wrote:
> Hi Dave:
> 
> This series of patches brings GRO performance to within 1% of LRO
> on the slow machine that I was testing.  I can overtake LRO by
> deleting the IP checksum test and the Ethernet header test from
> GRO, which LRO doesn't do anyway, but that's not very nice :)
> 
> I'm still looking at other optimisations as time allows.

A few questions for you: I've been looking a bit into potential GRO 
optimisations that are possible with the vxge driver.  At least from my 
existing testing on a P4 Xeon, it seems that doing packet rx via 
napi_gro_receive() was a bit slower.  I'll retest with these changes 
of yours.  What platform have your tests been run on?  Also, do you have 
any notes/ideas on how best to make use of the GRO functionality within 
the kernel?  I'm hoping it's possible to make use of a few of the hardware 
hints to improve fast path performance.

	-ben