netdev - Re: [PATCH net-next 1/2] mptcp: don't need to check SKB_EXT_MPTCP in mptcp_reset

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Message-ID: <CAL+tcoBEkK-ncB6zdJrq7kkd3MEdyT7_ONOyB=0cVVR_oj-4yA@mail.gmail.com>
Date: Fri, 5 Apr 2024 15:58:14 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: Paolo Abeni <pabeni@...hat.com>
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org, 
	matttbe@...nel.org, martineau@...nel.org, geliang@...nel.org, 
	mptcp@...ts.linux.dev, netdev@...r.kernel.org, 
	Jason Xing <kernelxing@...cent.com>
Subject: Re: [PATCH net-next 1/2] mptcp: don't need to check SKB_EXT_MPTCP in mptcp_reset_option()

Hello Paolo,

On Fri, Apr 5, 2024 at 3:47 PM Paolo Abeni <pabeni@...hat.com> wrote:
>
> On Fri, 2024-04-05 at 10:39 +0800, Jason Xing wrote:
> > From: Jason Xing <kernelxing@...cent.com>
> >
> > Before this, what mptcp_reset_option() checks is totally the same as
> > mptcp_get_ext() does, so we could skip it.
>
> Note that the somewhat duplicate test is (a possibly not great)
> optimization to avoid jumping in the mptcp code (possible icache
> misses) for plain TCP sockets.
>
> I guess we want to maintain it.

Okay, I just read code and found the duplication but may I ask why it
has something to do with icache misses?

Thanks,
Jason

>
> Cheers,
>
> Paolo
>