netdev - Re: [PATCH net-next] tcp: gro: inline tcp_gro_pull

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CANn89iLhp47dfpFc_Ldks6nUtv497TmiBK55o-W7ESW+kj0kHQ@mail.gmail.com>
Date: Fri, 14 Nov 2025 10:47:35 -0800
From: Eric Dumazet <edumazet@...gle.com>
To: Alexander Lobakin <aleksander.lobakin@...el.com>
Cc: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, 
	Kuniyuki Iwashima <kuniyu@...gle.com>, netdev@...r.kernel.org, eric.dumazet@...il.com
Subject: Re: [PATCH net-next] tcp: gro: inline tcp_gro_pull_header()

On Fri, Nov 14, 2025 at 8:39 AM Alexander Lobakin
<aleksander.lobakin@...el.com> wrote:
>
> From: Eric Dumazet <edumazet@...gle.com>
> Date: Fri, 14 Nov 2025 08:09:31 -0800
>
> > On Fri, Nov 14, 2025 at 7:56 AM Alexander Lobakin
> > <aleksander.lobakin@...el.com> wrote:
> >>
> >> From: Eric Dumazet <edumazet@...gle.com>
> >> Date: Thu, 13 Nov 2025 14:03:57 +0000
> >>
> >>> tcp_gro_pull_header() is used in GRO fast path, inline it.
> >>
> >> Looks reasonable, but... any perf numbers? bloat-o-meter stats?
> >
> > This is used two times, one from IPv4, one from IPv6.
> >
> > FDO usually embeds this function in the two callers, this patch
> > reduces the gap between FDO and non FDO kernels.
> > Non FDO builds get a ~0.5 % performance increase with this patch, for
> > a cost of less than 192 bytes on x86_64.
>
> I asked for these as you usually provide detailed stats with `perf top`
> output etc, but not this time.

Because I am currently chasing many small optimizations, and they hit
various subsystems.

>
> (although you always require to provide perf stats when someone else
>  sends an optimization patch)
>
> >
> > It might sound small, but adding all these changes together is not small.
>
> A couple weeks ago you wrote that 1% of perf improvement is "a noise".
>
> I'm not against this patch (if you add everything from the above to the
> commit message + maybe your usual detailed stats).
> +0.5% for 192 bytes sounds good to me (I don't call it "a noise").
>
> But from my PoV this just feels like "my 0.5% is bigger than your 1%"
> and "you have to show me the numbers, and I don't".
>
> The rules are the same for everyone.

Sure, thank you so much !