From: Eric Dumazet <eric.dumazet@gmail.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: brakmo <brakmo@fb.com>, netdev <netdev@vger.kernel.org>,
Martin Lau <kafai@fb.com>, Alexei Starovoitov <ast@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Kernel Team <Kernel-team@fb.com>
Subject: Re: [PATCH bpf-next 0/7] bpf: Propagate cn to TCP
Date: Tue, 26 Mar 2019 08:43:11 -0700 [thread overview]
Message-ID: <dc646bb8-d55c-affa-252b-1299535a2ea7@gmail.com> (raw)
In-Reply-To: <20190326150712.4zi6idzva3ivaupg@ast-mbp>
On 03/26/2019 08:07 AM, Alexei Starovoitov wrote:
> so after 20+ years linux qdisc design is wrong?
Yes it is how it is, return values can not be propagated back to the TCP stack in all cases.
When a packet is queued to Qdisc 1, there is no way we can return
a value that can represent what the packet becomes when dequeued later and queued into Qdisc 2.
Also some qdisc take their drop decision later (eg : codel and fq_codel), so ->enqueue() will
return a success which might be a lie.
> bpf is about choice. We have to give people tools to experiment even
> when we philosophically disagree on the design.
Maybe, but I feel that for the moment, the choice is only for FB, and rest
of the world has to re-invent private ebpf code in order to benefit from all of this.
I doubt many TCP users will have the skills/money to benefit from this.
Meanwhile, we as a community have to maintain a TCP/IP stack with added hooks and complexity.
It seems TCP stack became a playground for experiments.
next prev parent reply other threads:[~2019-03-26 15:43 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-23 8:05 [PATCH bpf-next 0/7] bpf: Propagate cn to TCP brakmo
2019-03-23 8:05 ` [PATCH bpf-next 1/7] bpf: Create BPF_PROG_CGROUP_INET_EGRESS_RUN_ARRAY brakmo
2019-03-23 8:05 ` [PATCH bpf-next 2/7] bpf: cgroup inet skb programs can return 0 to 3 brakmo
2019-03-23 8:05 ` [PATCH bpf-next 3/7] bpf: Update __cgroup_bpf_run_filter_skb with cn brakmo
2019-03-23 8:05 ` [PATCH bpf-next 4/7] bpf: Update BPF_CGROUP_RUN_PROG_INET_EGRESS calls brakmo
2019-03-23 8:05 ` [PATCH bpf-next 5/7] bpf: sysctl for probe_on_drop brakmo
2019-03-23 8:05 ` [PATCH bpf-next 6/7] bpf: Add cn support to hbm_out_kern.c brakmo
2019-03-23 8:05 ` [PATCH bpf-next 7/7] bpf: Add more stats to HBM brakmo
2019-03-23 9:12 ` [PATCH bpf-next 0/7] bpf: Propagate cn to TCP Eric Dumazet
2019-03-23 15:41 ` Alexei Starovoitov
2019-03-24 5:36 ` Eric Dumazet
2019-03-24 16:19 ` Alexei Starovoitov
2019-03-25 8:33 ` Eric Dumazet
2019-03-25 8:48 ` Eric Dumazet
2019-03-26 4:27 ` Alexei Starovoitov
2019-03-26 8:06 ` Eric Dumazet
2019-03-26 15:07 ` Alexei Starovoitov
2019-03-26 15:43 ` Eric Dumazet [this message]
2019-03-26 17:01 ` Alexei Starovoitov
2019-03-26 18:07 ` Eric Dumazet
2019-03-26 8:13 ` Eric Dumazet
2019-03-24 5:48 ` Eric Dumazet
2019-03-24 1:14 ` Lawrence Brakmo
2019-03-24 5:58 ` Eric Dumazet
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