netdev - Re: [PATCH v2 net-next] net: snmp: add statistics for tcp small queue check

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Message-ID: <CANn89iJ0Txbb7wvgKSPMLhHE0X8cadayN8ULZJkEvrC8YTwkow@mail.gmail.com>
Date:   Mon, 29 Nov 2021 08:37:50 -0800
From:   Eric Dumazet <edumazet@...gle.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     menglong8.dong@...il.com, davem@...emloft.net,
        yoshfuji@...ux-ipv6.org, dsahern@...nel.org, imagedong@...cent.com,
        ycheng@...gle.com, kuniyu@...zon.co.jp,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH v2 net-next] net: snmp: add statistics for tcp small queue check

On Mon, Nov 29, 2021 at 7:57 AM Jakub Kicinski <kuba@...nel.org> wrote:
>
> On Sun, 28 Nov 2021 14:01:02 +0800 menglong8.dong@...il.com wrote:
> > Once tcp small queue check failed in tcp_small_queue_check(), the
> > throughput of tcp will be limited, and it's hard to distinguish
> > whether it is out of tcp congestion control.
> >
> > Add statistics of LINUX_MIB_TCPSMALLQUEUEFAILURE for this scene.
>
> Isn't this going to trigger all the time and alarm users because of the
> "Failure" in the TCPSmallQueueFailure name?  Isn't it perfectly fine
> for TCP to bake full TSQ amount of data and have it paced out onto the
> wire? What's your link speed?

Yes, I would be curious to have some instructions on how this new SNMP
variable can be used,
in a concrete case.

Like, how getting these SNMP values can translate to an action, giving
more throughput ?