netdev - RE: GRO aggregation

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Message-ID: <1347392132.13103.663.camel@edumazet-glaptop>
Date:	Tue, 11 Sep 2012 21:35:32 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Shlomo Pongratz <shlomop@...lanox.com>
Cc:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: GRO aggregation

On Tue, 2012-09-11 at 19:24 +0000, Shlomo Pongratz wrote:

> 
> I see that in ixgbe the weight for the NAPI is 64 (netif_napi_add). So
> if packets are arriving in high rate then an the CPU is fast enough to
> collect the packets as they arrive, assuming packets continue to
> arrives while the NAPI runs. Then it should have aggregate more. So we
> will have less passes trough the stack.
> 

As I said, _if_ your cpu was loaded by other stuff, then you would see
biggest GRO packets.

GRO is not : "We want to kill latency and have big packets just because
its better"

Its more like : If load is big enough, try to aggregate TCP frames in
less skbs.



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