netdev - Re: [RFC Patch] tcp: make icsk_retransmit

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Message-ID: <CAM_iQpUs-qjs_X4iCGENb89hXNjnxK1-Bb+KWUzgYcmuqeGbPw@mail.gmail.com>
Date:   Fri, 1 Nov 2019 16:51:03 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     netdev <netdev@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [RFC Patch] tcp: make icsk_retransmit_timer pinned

On Fri, Nov 1, 2019 at 4:44 PM Eric Dumazet <edumazet@...gle.com> wrote:
>
> On Fri, Nov 1, 2019 at 3:43 PM Cong Wang <xiyou.wangcong@...il.com> wrote:
>
> > So let's make the sysctl timer_migration disabled by default? It is
> > always how we want to trade off CPU power saving with latency.
>
> At least timer_migration sysctl deserves a proper documentation.
> I do not see any.
>
> And maybe automatically disable it for hosts with more than 64
> possible cpus would make sense,
> but that  is only a suggestion. I won't fight this battle.
>
> (All sysctls can be set by admins, we do not need to change the default)

Make people rely on the default value, as obviously not everyone
is able to revise all of the sysctl's.

Anyway, I read it as the patch makes TCP retransmit timer pinned
not interesting, therefore let's discard it. We can at least carry it
by ourselves, so not a big deal.

Thanks!