From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Eric Dumazet <eric.dumazet@gmail.com>,
"David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>
Cc: netdev <netdev@vger.kernel.org>,
Eric Dumazet <edumazet@google.com>,
Eric Dumazet <eric.dumazet@gmail.com>,
Neal Cardwell <ncardwell@google.com>,
Ingemar Johansson S <ingemar.s.johansson@ericsson.com>,
Tom Henderson <tomh@tomh.org>, Bob Briscoe <in@bobbriscoe.net>
Subject: Re: [PATCH net-next 2/2] fq_codel: implement L4S style ce_threshold_ect1 marking
Date: Thu, 14 Oct 2021 21:54:23 +0200 [thread overview]
Message-ID: <87wnmf1ixc.fsf@toke.dk> (raw)
In-Reply-To: <20211014175918.60188-3-eric.dumazet@gmail.com>
Eric Dumazet <eric.dumazet@gmail.com> writes:
> From: Eric Dumazet <edumazet@google.com>
>
> Add TCA_FQ_CODEL_CE_THRESHOLD_ECT1 boolean option to select Low Latency,
> Low Loss, Scalable Throughput (L4S) style marking, along with ce_threshold.
>
> If enabled, only packets with ECT(1) can be transformed to CE
> if their sojourn time is above the ce_threshold.
>
> Note that this new option does not change rules for codel law.
> In particular, if TCA_FQ_CODEL_ECN is left enabled (this is
> the default when fq_codel qdisc is created), ECT(0) packets can
> still get CE if codel law (as governed by limit/target) decides so.
The ability to have certain packets receive a shallow marking threshold
and others regular ECN semantics is no doubt useful. However, given that
it is by no means certain how the L4S experiment will pan out (and I for
one remain sceptical that the real-world benefits will turn out to match
the tech demos), I think it's premature to bake the ECT(1) semantics
into UAPI.
So how about tying this behaviour to a configurable skb->mark instead?
That way users can get the shallow marking behaviour for any subset of
packets they want, simply by installing a suitable filter on the
qdisc...
-Toke
next prev parent reply other threads:[~2021-10-14 19:54 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-14 17:59 [PATCH net-next 0/2] net/sched: implement L4S style ce_threshold_ect1 marking Eric Dumazet
2021-10-14 17:59 ` [PATCH net-next 1/2] net: add skb_get_dsfield() helper Eric Dumazet
2021-10-14 17:59 ` [PATCH net-next 2/2] fq_codel: implement L4S style ce_threshold_ect1 marking Eric Dumazet
2021-10-14 19:54 ` Toke Høiland-Jørgensen [this message]
2021-10-14 21:35 ` Eric Dumazet
2021-10-14 23:24 ` Toke Høiland-Jørgensen
2021-10-16 7:39 ` Jonathan Morton
2021-10-17 11:22 ` Bob Briscoe
2021-10-17 12:18 ` Jonathan Morton
2021-10-18 19:43 ` Gorry Fairhurst
2021-10-15 12:59 ` Bob Briscoe
2021-10-15 14:08 ` Eric Dumazet
2021-10-15 15:49 ` Neal Cardwell
2021-10-17 0:42 ` Bob Briscoe
2021-10-18 11:42 ` Dave Taht
2021-10-15 10:40 ` [PATCH net-next 0/2] net/sched: " patchwork-bot+netdevbpf
2021-10-15 13:01 ` Toke Høiland-Jørgensen
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