netdev - Re: [PATCH net-next 0/2] tcp: add sysctl_tcp_rto_min

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Message-ID: <CAL+tcoCR1Uh1fvVzf5pVyHTv+dHDK1zfbDTtuH_q1CMggUZqkA@mail.gmail.com>
Date: Wed, 29 May 2024 14:43:05 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: Kevin Yang <yyd@...gle.com>
Cc: David Miller <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org
Subject: Re: [PATCH net-next 0/2] tcp: add sysctl_tcp_rto_min_us

Hello Kevin,

On Wed, May 29, 2024 at 1:13 AM Kevin Yang <yyd@...gle.com> wrote:
>
> Adding a sysctl knob to allow user to specify a default
> rto_min at socket init time.

I wonder what the advantage of this new sysctl knob is since we have
had BPF or something like that to tweak the rto min already?

There are so many places/parameters of the TCP stack that can be
exposed to the user side and adjusted by new sysctls...

Thanks,
Jason

>
> After this patch series, the rto_min will has multiple sources:
> route option has the highest precedence, followed by the
> TCP_BPF_RTO_MIN socket option, followed by this new
> tcp_rto_min_us sysctl.
>
> Kevin Yang (2):
>   tcp: derive delack_max with tcp_rto_min helper
>   tcp: add sysctl_tcp_rto_min_us
>
>  Documentation/networking/ip-sysctl.rst | 13 +++++++++++++
>  include/net/netns/ipv4.h               |  1 +
>  net/ipv4/sysctl_net_ipv4.c             |  8 ++++++++
>  net/ipv4/tcp.c                         |  3 ++-
>  net/ipv4/tcp_ipv4.c                    |  1 +
>  net/ipv4/tcp_output.c                  | 11 ++---------
>  6 files changed, 27 insertions(+), 10 deletions(-)
>
> --
> 2.45.1.288.g0e0cd299f1-goog
>
>