Re: [Patch net-next 04/11] net:fec: add multiqueue support

From: Florian Fainelli <f.fainelli@gmail.com>
To: Zhi Li <lznuaa@gmail.com>
Cc: Frank Li <Frank.Li@freescale.com>,
	Duan Fugang-B38611 <b38611@freescale.com>,
	David Miller <davem@davemloft.net>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	Shawn Guo <shawn.guo@linaro.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>
Subject: Re: [Patch net-next 04/11] net:fec: add multiqueue support
Date: Wed, 3 Sep 2014 21:09:38 -0700	[thread overview]
Message-ID: <CAGVrzcaB=7qkXzZ46-86-obMJBTOZQ01N7PROdi9RrkiDnE2zQ@mail.gmail.com> (raw)
In-Reply-To: <CAHrpEqRSGg9=B8nk-PFkayP1kN8eQ5UnBvjikR5svub-wD-d6w@mail.gmail.com>

2014-09-03 20:41 GMT-07:00 Zhi Li <lznuaa@gmail.com>:
> On Wed, Sep 3, 2014 at 4:27 PM, Florian Fainelli <f.fainelli@gmail.com> wrote:
>> On 09/03/2014 01:38 PM, Frank Li wrote:
>>> From: Fugang Duan <B38611@freescale.com>
>>>
>>> Add multiqueue support, which is compatible with previous single queue
>>> driver for FEC/ENET IPs.
>>>
>>> By default, the tx/rx queue number is 1, user can config the queue number
>>> at DTS file like this:
>>>       fsl,num_tx_queues=<3>;
>>>       fsl,num_rx_queues=<3>;
>>>
>>> Ethernet multiqueue mechanism can improve performance in SMP system.
>>> For single hw queue, multiqueue can balance cpu loading.
>>> For multi hw queues, multiple cores can process network packets in parallel,
>>> and refer the article for the detail advantage for multiqueue:
>>> http://vger.kernel.org/~davem/davem_nyc09.pdf
>>
>> You should probably split that patch in a minimum of two, or more
>> different parts.
>>
>> Two parts:
>>
>> - add TX multiqueue support
>> - add RX multiqueue support
>>
>
> I understood your concern.
> We also need consider logical integration.

Sure, hence the reason why I suggest you make it happen in different
parts, what you can do is make sure that you parse "fsl,num_tx_queues"
and "fsl,num_rx_queues" as one of the last patches in this patch
series. That way, we achieve a logical breakdown of the changes and
only support and enable multiqueue when the driver is ready.

>
> Separate this patch just reduce changed lines in a patch.

That is exactly my point, right now there is too much churn to make a
reviewer able to spot potential problems.

> Most of this patch change is from fep-> to txq-> or rxq->
>
> best regards
> Frank Li
>
>> More parts:
>>
>> - prepare for TX multiqueue (introduce queue structure, definitions)
>> - transition TX path to use queue 0
>> - add support for the two other TX queues
>> - prepare for RX multiqueue (introduce queue structure, definitions)
>> - prepare for multiqueue, hardcode RX path to use queue 0
>> - add support for the two other RX queues
>>
>> The number of changes are extremely hard to review...
>> --
>> Florian

-- 
Florian