Re: [PATCHv10 net-next] tcp: Add TCP ROCCET congestion control module.

[patchwork-bot+netdevbpf@kernel.org]

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Thu, 8 Oct 2026 11:16:36 +0200 you wrote:
> TCP ROCCET is a new congestion control algorithm based on TCP CUBIC
> that improves its overall performance in cellular networks. By its mode
> of function, CUBIC causes bufferbloat while it tries to detect the
> available throughput of a network path. This is particularly a problem
> with large buffers in mobile networks. A more detailed description and
> analysis of this problem caused by TCP CUBIC can be found in [1].
> TCP ROCCET's main method of addressing the bufferbloat problem is by
> adding two additional metrics. The first metric is the relative increase
> in RTT from its minimum, the srRTT. Here, bufferbloat can be detected
> when RTTs increase due to buffer filling. The second metric is the
> acknowledgment arrival rate sampled over 100ms intervals and the bytes
> sent and received over 5 RTTs. If CUBIC increases the send rate or
> congestion window, and the acknowledgment arrival rate stays at the
> same level, the connection is limited by the bottleneck link's capacity.
> In such cases, ROCCET reduces the send rate to prevent bufferbloat.
> ROCCET uses a modified version of slow start rather than HyStart because
> HyStart is known to enter the congestion avoidance phase too early when
> used in cellular networks [2]. Therefore, ROCCET uses a combination of
> srRTT and the acknowledgment arrival rate to determine when to exit slow
> start. For the congestion avoidance phase, ROCCET relies on the srRTT and
> monitoring the sent and received bytes to detect the filling of the
> bottleneck buffer. To keep the minimum RTT updated, ROCCET performs
> minimum RTT probing if no new minimum RTT was found in the last 5 seconds.
> To this end ROCCET halves the cwnd and probes for 200ms but at least for
> one RTT, for a new minimum RTT. After probing, ROCCET refills the pipe
> carefully. In addition, ROCCET reacts to packet loss by adapting CUBIC's
> behavior. ECNs are handled as ROCCET congestion event, where the cwnd gets
> reduced and ROCCET enters a buffer drain state.
> 
> [...]

Here is the summary with links:
  - [PATCHv10,net-next] tcp: Add TCP ROCCET congestion control module.
    https://git.kernel.org/netdev/net-next/c/819d59638796

You are awesome, thank you!
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