From mboxrd@z Thu Jan  1 00:00:00 1970
From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= <toke@toke.dk>
Subject: Re: [PATCH net-next v12 3/7] sch_cake: Add optional ACK filter
Date: Thu, 17 May 2018 15:11:31 +0200
Message-ID: <877eo2xw8s.fsf@toke.dk>
References: <152650253056.25701.10138252969621361651.stgit@alrua-kau> <152650254614.25701.1377066681230937234.stgit@alrua-kau> <a002ff7b-2606-afcd-1769-b216f4db428c@gmail.com> <87in7my196.fsf@toke.dk> <541d62af-3938-5fdc-666c-dd243fa465b5@gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
Cc: cake@lists.bufferbloat.net
To: Eric Dumazet <eric.dumazet@gmail.com>, netdev@vger.kernel.org
Return-path: <netdev-owner@vger.kernel.org>
Received: from mail.toke.dk ([52.28.52.200]:56761 "EHLO mail.toke.dk"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1751356AbeEQNLf (ORCPT <rfc822;netdev@vger.kernel.org>);
        Thu, 17 May 2018 09:11:35 -0400
In-Reply-To: <541d62af-3938-5fdc-666c-dd243fa465b5@gmail.com>
Sender: netdev-owner@vger.kernel.org
List-ID: <netdev.vger.kernel.org>

Eric Dumazet <eric.dumazet@gmail.com> writes:

> On 05/17/2018 04:23 AM, Toke H=C3=B8iland-J=C3=B8rgensen wrote:
>
>>=20
>> We don't do full parsing of SACKs, no; we were trying to keep things
>> simple... We do detect the presence of SACK options, though, and the
>> presence of SACK options on an ACK will make previous ACKs be considered
>> redundant.
>>=20
>
> But they are not redundant in some cases, particularly when reorders
> happen in the network.

Huh. I was under the impression that SACKs were basically cumulative
until cleared.

I.e., in packet sequence ABCDE where B and D are lost, C would have
SACK(B) and E would have SACK(B,D). Are you saying that E would only
have SACK(D)?

-Toke