netdev - Re: [RFC PATCH net-next] net: add an entry for CONFIG_NET_RX_BUSY

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Message-ID: <CANn89i+3c3fg1SYEpx02yCKHfBoZvYJt=wTqgZ77nCWzN0q-Wg@mail.gmail.com>
Date: Tue, 23 Jul 2024 17:26:05 +0200
From: Eric Dumazet <edumazet@...gle.com>
To: Jason Xing <kerneljasonxing@...il.com>
Cc: davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com, horms@...nel.org, 
	netdev@...r.kernel.org, Jason Xing <kernelxing@...cent.com>
Subject: Re: [RFC PATCH net-next] net: add an entry for CONFIG_NET_RX_BUSY_POLL

On Tue, Jul 23, 2024 at 5:13 PM Jason Xing <kerneljasonxing@...il.com> wrote:
>
> On Tue, Jul 23, 2024 at 11:09 PM Jason Xing <kerneljasonxing@...il.com> wrote:
> >
> > On Tue, Jul 23, 2024 at 10:57 PM Eric Dumazet <edumazet@...gle.com> wrote:
> > >
> > > On Tue, Jul 23, 2024 at 3:57 PM Jason Xing <kerneljasonxing@...il.com> wrote:
> > > >
> > > > From: Jason Xing <kernelxing@...cent.com>
> > > >
> > > > When I was doing performance test on unix_poll(), I found out that
> > > > accessing sk->sk_ll_usec when calling sock_poll()->sk_can_busy_loop()
> > > > occupies too much time, which causes around 16% degradation. So I
> > > > decided to turn off this config, which cannot be done apparently
> > > > before this patch.
> > >
> > > Too many CONFIG_ options, distros will enable it anyway.
> > >
> > > In my builds, offset of sk_ll_usec is 0xe8.
> > >
> > > Are you using some debug options or an old tree ?
>
> I forgot to say: I'm running the latest kernel which I pulled around
> two hours ago. Whatever kind of configs with/without debug options I
> use, I can still reproduce it.

Ok, please post :

pahole --hex -C sock vmlinux