From: Jakub Kicinski <kuba@kernel.org>
To: Eric Dumazet <edumazet@google.com>
Cc: "David S . Miller" <davem@davemloft.net>,
Paolo Abeni <pabeni@redhat.com>, Simon Horman <horms@kernel.org>,
Neal Cardwell <ncardwell@google.com>,
Kuniyuki Iwashima <kuniyu@google.com>,
netdev@vger.kernel.org, eric.dumazet@gmail.com
Subject: Re: [PATCH net-next] tcp: add cwnd_event_tx_start to tcp_congestion_ops
Date: Fri, 13 Mar 2026 15:07:10 -0700 [thread overview]
Message-ID: <20260313150710.0edaa6b9@kernel.org> (raw)
In-Reply-To: <20260313202802.1201129-1-edumazet@google.com>
On Fri, 13 Mar 2026 20:28:02 +0000 Eric Dumazet wrote:
> (tcp_congestion_ops)->cwnd_event() is called very often, with
> @event oscillating between CA_EVENT_TX_START and other values.
>
> This is not branch prediction friendly.
>
> Provide a new cwnd_event_tx_start pointer dedicated for CA_EVENT_TX_START.
>
> Both BBR and CUBIC benefit from this change, since they only care
> about CA_EVENT_TX_START.
BPF selftest are not happy:
857
progs/tcp_ca_kfunc.c:121:33: error: use of undeclared identifier 'cwnd_event_tx_start'
121 | .cwnd_event_tx_start = (void *)cwnd_event_tx_start,
| ^~~~~~~~~~~~~~~~~~~
--
pw-bot: cr
next prev parent reply other threads:[~2026-03-13 22:07 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-13 20:28 [PATCH net-next] tcp: add cwnd_event_tx_start to tcp_congestion_ops Eric Dumazet
2026-03-13 22:07 ` Jakub Kicinski [this message]
2026-03-14 4:13 ` Eric Dumazet
2026-03-14 4:24 ` Eric Dumazet
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