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Message-ID: <517d5988-2e71-4ba5-9588-15218eebc8ef@manjusaka.me>
Date:   Tue, 8 Aug 2023 12:50:46 +0800
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Subject: Re: [PATCH] tracepoint: add new `tcp:tcp_ca_event_set` trace event
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To:     Neal Cardwell <ncardwell@google.com>
Cc:     edumazet@google.com, mhiramat@kernel.org, rostedt@goodmis.org,
        davem@davemloft.net, dsahern@kernel.org, kuba@kernel.org,
        pabeni@redhat.com, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
        bpf@vger.kernel.org
References: <20230807183308.9015-1-me@manjusaka.me>
 <CADVnQyn3UMa3Qx6cC1Rx97xLjQdG0eKsiF7oY9UR=b9vU4R-yA@mail.gmail.com>
From:   Manjusaka <me@manjusaka.me>
In-Reply-To: <CADVnQyn3UMa3Qx6cC1Rx97xLjQdG0eKsiF7oY9UR=b9vU4R-yA@mail.gmail.com>
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On 2023/8/8 04:00, Neal Cardwell wrote:
> On Mon, Aug 7, 2023 at 2:33 PM Manjusaka <me@manjusaka.me> wrote:
>>
>> In normal use case, the tcp_ca_event would be changed in high frequency.
>>
>> It's a good indicator to represent the network quanlity.
>>
>> So I propose to add a `tcp:tcp_ca_event_set` trace event
>> like `tcp:tcp_cong_state_set` to help the people to
>> trace the TCP connection status
>>
>> Signed-off-by: Manjusaka <me@manjusaka.me>
>> ---
>>  include/net/tcp.h          |  9 ++------
>>  include/trace/events/tcp.h | 45 ++++++++++++++++++++++++++++++++++++++
>>  net/ipv4/tcp_cong.c        | 10 +++++++++
>>  3 files changed, 57 insertions(+), 7 deletions(-)
>>
>> diff --git a/include/net/tcp.h b/include/net/tcp.h
>> index 0ca972ebd3dd..a68c5b61889c 100644
>> --- a/include/net/tcp.h
>> +++ b/include/net/tcp.h
>> @@ -1154,13 +1154,8 @@ static inline bool tcp_ca_needs_ecn(const struct sock *sk)
>>         return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
>>  }
>>
>> -static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
>> -{
>> -       const struct inet_connection_sock *icsk = inet_csk(sk);
>> -
>> -       if (icsk->icsk_ca_ops->cwnd_event)
>> -               icsk->icsk_ca_ops->cwnd_event(sk, event);
>> -}
>> +/* from tcp_cong.c */
>> +void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event);
>>
>>  /* From tcp_cong.c */
>>  void tcp_set_ca_state(struct sock *sk, const u8 ca_state);
>> diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
>> index bf06db8d2046..38415c5f1d52 100644
>> --- a/include/trace/events/tcp.h
>> +++ b/include/trace/events/tcp.h
>> @@ -416,6 +416,51 @@ TRACE_EVENT(tcp_cong_state_set,
>>                   __entry->cong_state)
>>  );
>>
>> +TRACE_EVENT(tcp_ca_event_set,
> 
> Regarding the proposed name, "tcp_ca_event_set"... including "set" in
> the name is confusing, since the tcp_ca_event() function is not really
> setting anything. :-)
> 
> The trace_tcp_cong_state_set() call you are using as a model has "set"
> in the name because the function it is tracing, tcp_set_ca_state(),
> has "set" in the name. :-)
> 
> Would it work to use something like:
>   TRACE_EVENT(tcp_ca_event,
> 
> thanks,
> neal

Emmmm, sorry about the confusing var name and thanks for the review. I will update my patch ASAP.

best regards
Manjusaka