linux-kernel - Re: [PATCH net-next v2] net: tcp: support to probe tcp receiver OOM

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Date:   Fri, 14 Jul 2023 17:56:03 +0800
From:   Menglong Dong <menglong8.dong@...il.com>
To:     Randy Dunlap <rdunlap@...radead.org>
Cc:     edumazet@...gle.com, ncardwell@...gle.com, davem@...emloft.net,
        kuba@...nel.org, pabeni@...hat.com, corbet@....net,
        dsahern@...nel.org, kuniyu@...zon.com, morleyd@...gle.com,
        imagedong@...cent.com, mfreemon@...udflare.com,
        mubashirq@...gle.com, netdev@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v2] net: tcp: support to probe tcp receiver OOM

On Thu, Jul 13, 2023 at 11:43 PM Randy Dunlap <rdunlap@...radead.org> wrote:
>
>
>
> On 7/13/23 04:24, menglong8.dong@...il.com wrote:
> > diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
> > index 4a010a7cde7f..3de2dce74037 100644
> > --- a/Documentation/networking/ip-sysctl.rst
> > +++ b/Documentation/networking/ip-sysctl.rst
> > @@ -694,6 +694,20 @@ tcp_retries2 - INTEGER
> >       RFC 1122 recommends at least 100 seconds for the timeout,
> >       which corresponds to a value of at least 8.
> >
> > +tcp_oom_retries - INTEGER
> > +     RTO retransmissions count of the receiver is recognised as OOM.
> > +     Given a value N, a hypothetical TCP connection will enter probe
> > +     state if N times RTO retransmissions performed and every
> > +     retransmission gets a pure ack, who doesn't contain SACK block.
>
>                                    ACK
> > +
> > +     The default value is 0, which means disable the OOM detection.
> > +     If disabled, skb will be dropped directly, without sending an
> > +     ACK, when rmem schedule fails. The function is valid only if sack
>
>                                                                      SACK
>
> > +     is enabled.
> > +
> > +     3 is the suggested value to enable this function. Do't make it
>
>                                                           Don't
>
> > +     greater than tcp_retries2.
>

Thanks! I'll fix them in the next version.

> --
> ~Randy