netdev - Re: [PATCH net-next 2/5] virtio_net: Add page

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Date: Mon, 4 Dec 2023 13:24:28 +0800
From: Zhu Yanjun <yanjun.zhu@...ux.dev>
To: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Cc: Liang Chen <liangchen.linux@...il.com>, jasowang@...hat.com,
 virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, kuba@...nel.org, edumazet@...gle.com,
 davem@...emloft.net, pabeni@...hat.com, alexander.duyck@...il.com,
 "Michael S. Tsirkin" <mst@...hat.com>
Subject: Re: [PATCH net-next 2/5] virtio_net: Add page_pool support to improve
 performance

在 2023/12/1 9:38, Xuan Zhuo 写道:
> On Thu, 30 Nov 2023 13:30:40 +0800, Zhu Yanjun <yanjun.zhu@...ux.dev> wrote:
>>
>> 在 2023/11/30 10:34, Xuan Zhuo 写道:
>>> On Wed, 29 Nov 2023 23:29:10 +0800, Zhu Yanjun <yanjun.zhu@...ux.dev> wrote:
>>>> 在 2023/11/29 23:22, Zhu Yanjun 写道:
>>>>> 在 2023/11/29 22:59, Michael S. Tsirkin 写道:
>>>>>> On Wed, Nov 29, 2023 at 10:50:57PM +0800, Zhu Yanjun wrote:
>>>>>>> 在 2023/5/26 13:46, Liang Chen 写道:
>>>>>> what made you respond to a patch from May, now?
>>>>> I want to apply page_pool to our virtio_net. This virtio_net works on
>>>>> our device.
>>>>>
>>>>> I want to verify whether page_pool on virtio_net with our device can
>>>>> improve the performance or not.
>>>>>
>>>>> And I found that ethtool is wrong.
>>>>>
>>>>> I use virtio_net on our device. I found that page member variable in
>>>>> rq is not used in recv path.
>>>>>
>>>>> When virtio_net is modprobe, I checked page member variable in rq with
>>>>> kprobe or crash tool.  page member variable in rq is always NULL.
>>>>>
>>>>> But sg in recv path is used.
>>>>>
>>>>> So how to use page member variable in rq? If page member variable in
>>>>> rq is always NULL, can we remove it?
>>>>>
>>>>> BTW, I use ping and iperf tool to make tests with virtio_net. In the
>>>>> tests, page member variable in rq is always NULL.
>>>>
>>>> And I replaced page member variable in rq with page_pool, but the
>>>> statistics of page_pool are always 0.
>>>>
>>>> It is interesting that page_pool member variable in rq is not used in
>>>> ping and iperf tests.
>>>>
>>>> I am not sure what tests can make page member variable not NULL. ^_^
>>> Do you mean rq->pages?
>>>
>>> That is for big mode.
>>
>> Hi, Xuan
>>
>> Got it. What is big mode? Do you mean big packet size? I run iperf with
>> the packet size 2^23.
>>
>> The rq->pages is still NULL.
>>
>> It is interesting.
> 
> You may need to check the code of virtnet_probe().

Thanks a lot. From virtnet_probe, big mode and mergeable mode can be found.

Zhu Yanjun

> 
> Thanks.
> 
> 
>>
>> Zhu Yanjun
>>
>>
>>>
>>> Thanks.
>>>
>>>
>>>> Best Regards,
>>>>
>>>> Zhu Yanjun
>>>>
>>>>
>>>>> It is interesting.
>>>>>
>>>>> Zhu Yanjun
>>>>>