From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eliezer Tamir <eliezer.tamir@linux.intel.com>
Subject: Re: [RFC PATCH 3/5] ixgbe: Add support for ndo_ll_poll
Date: Wed, 27 Feb 2013 21:20:02 +0200
Message-ID: <512E5C62.2030507@linux.intel.com>
References: <20130227175549.10611.82188.stgit@gitlad.jf.intel.com>  <20130227175606.10611.55498.stgit@gitlad.jf.intel.com> <1361990502.15793.0.camel@edumazet-glaptop>
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Cc: Eliezer Tamir <eliezer.tamir@linux.jf.intel.com>,
	linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
	Dave Miller <davem@davemloft.net>,
	Jesse Brandeburg <jesse.brandeburg@intel.com>,
	e1000-devel@lists.sourceforge.net,
	Willem de Bruijn <willemb@google.com>,
	Andi Kleen <andi@firstfloor.org>, HPA <hpa@zytor.com>,
	Eliezer Tamir <eliezer@tamir.org.il>
To: Eric Dumazet <eric.dumazet@gmail.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <1361990502.15793.0.camel@edumazet-glaptop>
Sender: linux-kernel-owner@vger.kernel.org
List-Id: netdev.vger.kernel.org

On 27/02/2013 20:41, Eric Dumazet wrote:
> On Wed, 2013-02-27 at 09:56 -0800, Eliezer Tamir wrote:
>
>> @@ -1458,7 +1459,9 @@ static void ixgbe_rx_skb(struct ixgbe_q_vector *q_vector,
>>   {
>>   	struct ixgbe_adapter *adapter = q_vector->adapter;
>>
>> -	if (!(adapter->flags & IXGBE_FLAG_IN_NETPOLL))
>> +	if (ixgbe_qv_ll_polling(q_vector))
>> +		netif_receive_skb(skb);
>> +	else if (!(adapter->flags & IXGBE_FLAG_IN_NETPOLL))
>>   		napi_gro_receive(&q_vector->napi, skb);
>>   	else
>>   		netif_rx(skb);
>
> Interesting reordering issue here.
yes, we need to fix this.
Maybe force a GRO flush when spinning, or maybe disable GRO in a more 
global manner when someone is busy-polling

> Why by-passing GRO stack if its enabled ?
you want to bypass GRO because it adds latency.