Discussion of explicit congestion notification's impact on the Internet
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From: Pete Heist <pete@heistp.net>
To: Dave Taht <dave.taht@gmail.com>
Cc: ECN-Sane <ecn-sane@lists.bufferbloat.net>
Subject: Re: [Ecn-sane] SCE pacing (was: a data point on syn and dscp)
Date: Wed, 10 Mar 2021 09:22:25 +0100	[thread overview]
Message-ID: <f86d40c14bc945fa547cfad37863900a02004285.camel@heistp.net> (raw)
In-Reply-To: <CAA93jw44H-uB+x=qhjQrBPL58JXxV2zPL93dKCbW_iZMxgwZRg@mail.gmail.com>

Not sure if this covers it, but there was a brief time before we had
enabled pacing programmatically in our TCP CCAs. There's a sysctl with
default:

net.ipv4.tcp_sce_pacing = 1

and in each CCA:

if (sock_net(sk)->ipv4.sysctl_tcp_sce_pacing)
    cmpxchg(&sk->sk_pacing_status, SK_PACING_NONE, SK_PACING_NEEDED);

This should enable the internal pacing mechanism in the kernel, which
is different from the one used by the fq qdisc, iirc.

On Tue, 2021-03-09 at 10:58 -0800, Dave Taht wrote:
> 
> this leads to my final question in that early sce and l4s experiments
> did have a lot of trouble with having to pace the initial burst, and I
> don't know what is actually done there, now, in current oses.
> 



      reply	other threads:[~2021-03-10  8:22 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-09 18:58 [Ecn-sane] a data point on syn and dscp Dave Taht
2021-03-10  8:22 ` Pete Heist [this message]

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