From: Stanislav Fomichev <sdf@fomichev.me>
To: Rao Shoaib <rao.shoaib@oracle.com>
Cc: sdf@google.com, Eric Dumazet <edumazet@google.com>,
priyarjha@google.com, ycheng@google.com, soheil@google.com,
daniel@iogearbox.net, netdev@vger.kernel.org,
bpf@vger.kernel.org
Subject: Re: bpf: add BPF_CGROUP_SOCK_OPS callback that is executed on every RTT (commit: 23729ff23186424)
Date: Thu, 25 Jul 2024 20:29:49 -0700 [thread overview]
Message-ID: <ZqMYLWFWEC0OWjrl@mini-arch> (raw)
In-Reply-To: <2628656e-ea6f-4885-8fbc-bd14f07a5b00@oracle.com>
On 07/25, Rao Shoaib wrote:
> Hi Stanislav,
>
> I have a question about the placement of tcp_bpf_rtt() call in
> tcp_rtt_estimator(). Why is the call made before the assignment
>
> tp->srtt_us = max(1U, srtt);
>
> How is the attached eBPF program suppose the get the new value?
Take a look at the way tcp_bpf_rtt is invoked. It gets mrtt_us
and srtt arguments. Those are passed via bpf_sock_ops args field.
See tools/testing/selftests/bpf/progs/tcp_rtt.c. Hope that helps!
prev parent reply other threads:[~2024-07-26 3:29 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-25 19:37 bpf: add BPF_CGROUP_SOCK_OPS callback that is executed on every RTT (commit: 23729ff23186424) Rao Shoaib
2024-07-26 3:29 ` Stanislav Fomichev [this message]
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