Message-ID: <af77ad0e-fde7-25da-dc3f-5d19133addba@intel.com>
Date:   Wed, 1 Feb 2023 12:15:02 +0100
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Subject: Re: [Intel-wired-lan] [PATCH v2 net] ixgbe: allow to increase MTU to
 some extent with XDP enabled
Content-Language: en-US
To:     Jason Xing <kerneljasonxing@gmail.com>
CC:     Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
        <jesse.brandeburg@intel.com>, <anthony.l.nguyen@intel.com>,
        <davem@davemloft.net>, <edumazet@google.com>, <kuba@kernel.org>,
        <pabeni@redhat.com>, <richardcochran@gmail.com>, <ast@kernel.org>,
        <daniel@iogearbox.net>, <hawk@kernel.org>,
        <john.fastabend@gmail.com>, <netdev@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <intel-wired-lan@lists.osuosl.org>,
        <bpf@vger.kernel.org>, Jason Xing <kernelxing@tencent.com>
References: <20230127122018.2839-1-kerneljasonxing@gmail.com>
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From:   Alexander Lobakin <alexandr.lobakin@intel.com>
In-Reply-To: <CAL+tcoBtQSeGi5diwUeg1LryYsB2wDg1ow19F2eApjh7hYbcsA@mail.gmail.com>
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From: Jason Xing <kerneljasonxing@gmail.com>
Date: Tue, 31 Jan 2023 19:23:59 +0800

> On Tue, Jan 31, 2023 at 7:08 PM Alexander Lobakin
> <alexandr.lobakin@intel.com> wrote:

[...]

>>>> You said in this thread that you've done several tests - what were they?
>>>
>>> Tests against XDP are running on the server side when MTU varies from
>>> 1500 to 3050 (not including ETH_HLEN, ETH_FCS_LEN and VLAN_HLEN) for a
>>
> 
>> BTW, if ixgbe allows you to set MTU of 3050, it needs to be fixed. Intel
>> drivers at some point didn't include the second VLAN tag into account,
> 
> Yes, I noticed that.
> 
> It should be like "int new_frame_size = new_mtu + ETH_HLEN +
> ETH_FCS_LEN + (VLAN_HLEN * 2)" instead of only one VLAN_HLEN, which is
> used to compute real size in ixgbe_change_mtu() function.
> I'm wondering if I could submit another patch to fix the issue you
> mentioned because the current patch tells a different issue. Does it
> make sense?

Yes, please send as a separate patch. It's somewhat related to the
topic, but better to keep commits atomic.

> 
> If you're available, please help me review the v3 patch I've already
> sent to the mailing-list. Thanks anyway.
> The Link is https://lore.kernel.org/lkml/20230131032357.34029-1-kerneljasonxing@gmail.com/
> .
> 
> Thanks,
> Jason

Thanks,
Olek