From: Stephen Hemminger <redacted>
Date: Mon, 30 Aug 2010 08:57:21 -0700

On Mon, 30 Aug 2010 06:42:31 +0000
Jarek Poplawski [off-list ref] wrote:

quoted

On 2010-08-29 20:39, Eric Dumazet wrote:

quoted

Le dimanche 29 aoĂťt 2010 Ă  10:06 -0700, David Miller a ĂŠcrit :

quoted

From: Jarek Poplawski <redacted>
Date: Sun, 29 Aug 2010 11:59:51 +0200

quoted

Actually, when GRO compares napi->dev to skb->dev?

Hmmm, I thought the code made a skb->dev comparison with the
existing SKBs in the list when checking for same-flow matches.

It doesn't, probably based upon the assumption that a NAPI
instance maps to a unique device, the very topic we're
discussing right now :-/

It does the check, Stephen added it in the commit I mentioned to start
this thread.

With net-next-2.6 this now reads :

Since Stephen didn't seem to miss this too much it seems quite obvious
to me this check should be removed.

No. I just don't use that system much, breaking code for
sake of one comparison is ridiculous.

It's not working to begin with.

I agree with Jarek that the check should be removed.  And GRO is one
of those places that, precisely, even one memory reference removal
can improve performance dramatically.

Herbert spent a lot of time doing micro-optimizations to make GRO
better and better, and the smallest things can turn out to make a huge
difference there.