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Message-ID: <57587b74-f865-4b56-8d65-a5cbc6826079@bytedance.com>
Date:   Fri, 1 Dec 2023 16:42:42 +0800
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Subject: Re: Re: [PATCH bpf-next] netkit: Add some ethtool ops to provide
 information to user
To:     Daniel Borkmann <daniel@iogearbox.net>,
        Nikolay Aleksandrov <razor@blackwall.org>, davem@davemloft.net,
        edumazet@google.com, kuba@kernel.org, pabeni@redhat.com
Cc:     bpf@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, yangzhenze@bytedance.com,
        wangdongdong.6@bytedance.com, tangchen.1@bytedance.com
References: <20231130075844.52932-1-zhoufeng.zf@bytedance.com>
 <51dd35c9-ff5b-5b11-04d1-9a5ae9466780@blackwall.org>
 <16b4d42d-2d62-460e-912f-6e3b86f3004d@bytedance.com>
 <94e335d4-ec90-ba78-b2b4-8419b25bfa88@iogearbox.net>
From:   Feng Zhou <zhoufeng.zf@bytedance.com>
In-Reply-To: <94e335d4-ec90-ba78-b2b4-8419b25bfa88@iogearbox.net>
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在 2023/11/30 18:56, Daniel Borkmann 写道:
> On 11/30/23 10:24 AM, Feng Zhou wrote:
>> 在 2023/11/30 17:06, Nikolay Aleksandrov 写道:
>>> On 11/30/23 09:58, Feng zhou wrote:
>>>> From: Feng Zhou <zhoufeng.zf@bytedance.com>
>>>>
>>>> Add get_strings, get_sset_count, get_ethtool_stats to get peer
>>>> ifindex.
>>>> ethtool -S nk1
>>>> NIC statistics:
>>>>       peer_ifindex: 36
>>>>
>>>> Add get_link, get_link_ksettings to get link stat.
>>>> ethtool nk1
>>>> Settings for nk1:
>>>>     ...
>>>>     Link detected: yes
>>>>
>>>> Add get_ts_info.
>>>> ethtool -T nk1
>>>> Time stamping parameters for nk1:
>>>> ...
>>>>
>>>> Signed-off-by: Feng Zhou <zhoufeng.zf@bytedance.com>
>>>> ---
>>>>   drivers/net/netkit.c | 53 
>>>> ++++++++++++++++++++++++++++++++++++++++++++
>>>>   1 file changed, 53 insertions(+)
>>>>
>>>
>>> Hi,
>>> I don't see any point in sending peer_ifindex through ethtool, even
>>> worse through ethtool stats. That is definitely the wrong place for it.
>>> You can already retrieve that through netlink. About the speed/duplex
>>> this one makes more sense, but this is the wrong way to do it.
>>> See how we did it for virtio_net (you are free to set speed/duplex
>>> to anything to please bonding for example). Although I doubt anyone 
>>> will use netkit with bonding, so even that is questionable. :)
>>>
>>> Nacked-by: Nikolay Aleksandrov <razor@blackwall.org>
>>
>> We use netkit to replace veth to improve performance, veth can be used 
>> ethtool -S veth to get peer_ifindex, so this part is added, as long as 
>> it is to keep the netkit part and veth unified, to ensure the same 
>> usage habits, and to replace it without perception.
> 
> Could you elaborate some more on the use case why you need to retrieve it
> via ethtool, what alternatives were tried and don't work?
> 
> Please also elaborate on the case for netkit_get_link_ksettings() and which
> concrete problem you are trying to address with this extension?
> 
> The commit message only explains what is done but does not go into the 
> detail
> of _why_ you need it.
> 
> Thanks,
> Daniel

In general, this information can be obtained through ip commands or 
netlink, and netkit_get_link_ksettings really not necessary. The reason 
why ethtool supports this is that when we use veth, our business 
colleagues are used to using ethtool to obtain peer_ifindex, and then 
replace netkit, found that it could not be used, resulting in their 
script failure, so they asked us for a request.