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From: David Miller <davem@davemloft.net>
Subject: Re: [E1000-devel] [PATCH] net: enable GRO by default for vlan
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Date: Wed, 15 Sep 2010 23:38:51 -0700 (PDT)
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From: Stephen Hemminger <shemminger@vyatta.com>
Date: Wed, 15 Sep 2010 23:21:25 -0700

> I think it is more complex than that. GRO is tied to NAPI,
> and bridge/bond don't use NAPI directly. They use netif_rx() for receiving
> because layered drivers can't directly up call because of possible
> issues with stack depth. 
> 
> To get GRO working for netif_rx case,
> the logic in process_backlog would have to change.
> But this queue is processing packets from multiple devices so
> it is not clear if GRO could be used.

Bonding's un-layering on RX is done in the normal netif_receive_skb()
control flow.

And bridging only uses netif_rx for multicast replication.