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From: Jakub Sitnicki <jakub@cloudflare.com>
To: Stanislav Fomichev <sdf.kernel@gmail.com>
Cc: Willem Ferguson <wferguson@cloudflare.com>,
	 netdev@vger.kernel.org, davem@davemloft.net,
	 edumazet@kernel.org,  kuba@kernel.org, pabeni@redhat.com,
	 ncardwell@google.com,  bpf@vger.kernel.org, ast@kernel.org,
	 daniel@iogearbox.net,  andrii@kernel.org, eddyz87@gmail.com,
	 memxor@gmail.com,  linux-doc@vger.kernel.org, corbet@lwn.net,
	 linux-kselftest@vger.kernel.org,  shuah@kernel.org,
	linux-kernel@vger.kernel.org,  kernel-team@cloudflare.com
Subject: Re: [RFC PATCH net-next 0/4] tcp: carry a BPF-chosen identifier in TSval low bits
Date: Mon, 19 Oct 2026 11:20:24 +0200	[thread overview]
Message-ID: <87a4oaf3mv.fsf@cloudflare.com> (raw)
In-Reply-To: <atFI9vl5hy09Dc0t@devvm7509.cco0.facebook.com> (Stanislav Fomichev's message of "Thu, 15 Oct 2026 14:45:02 -0700")

Hey Stan,

On Thu, Oct 15, 2026 at 02:45 PM -07, Stanislav Fomichev wrote:
> On 10/13, Willem Ferguson wrote:

[...]

>> Questions for reviewers:
>> 
>>  1. Is encoding an identifier in the low bits of TSval acceptable in
>>     principle, given the trade-offs above?
>>  2. If so, what feedback do you have on the implementation?
>
> Don't see any feedback yet, so from the top of my head: looks like you
> control two sides of the communication, so why not a custom (bpf) tcp option?
> Would you need that on every packet and it makes it expensive?
>
> Or any other field you can abuse maybe? IPv6 Flow label?

Nah, we don't control the client unfortunately.

Client here is any device that connects to our edge PoP.

> Implementation-wise, the sock_ops is going away in favor of bpf_tcp_ops,
> so BPF_SOCK_OPS_TCP_TS_ID_CB_FLAG is a no go.

Yeah, we have just recently realized [1].

Thanks for feedback.

[1] https://lore.kernel.org/all/877bjk893u.fsf@cloudflare.com/



  reply	other threads:[~2026-10-19  9:20 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-13 10:39 [RFC PATCH net-next 0/4] tcp: carry a BPF-chosen identifier in TSval low bits Willem Ferguson
2026-10-13 10:39 ` [RFC PATCH net-next 1/4] tcp: add plumbing to carry an " Willem Ferguson
2026-10-13 10:39 ` [RFC PATCH net-next 2/4] tcp: add BPF_SOCK_OPS_TCP_TS_ID_CB to assign a TSval identifier Willem Ferguson
2026-10-14 10:39   ` sashiko-bot
2026-10-14 17:50   ` Jakub Sitnicki
2026-10-15 12:12     ` Jason Xing
2026-10-13 10:39 ` [RFC PATCH net-next 3/4] tcp: add TCP_TS_ID socket option Willem Ferguson
2026-10-14 10:39   ` sashiko-bot
2026-10-13 10:39 ` [RFC PATCH net-next 4/4] selftests/bpf: add tcp_ts_id test Willem Ferguson
2026-10-15 21:45 ` [RFC PATCH net-next 0/4] tcp: carry a BPF-chosen identifier in TSval low bits Stanislav Fomichev
2026-10-19  9:20   ` Jakub Sitnicki [this message]
2026-10-20 17:58     ` Stanislav Fomichev

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