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SubjectRe: Get amount of fast retransmissions from TCP info
On Wed, May 3, 2017 at 3:47 PM, Lars Erik Storbukås
<storbukas.dev@gmail.com> wrote:
> I also want to count the amount of ECN signals received. Do anyone
> have any input on where to place an ECN signal count?
>
> Is any of these locations a logical place to increase the ECN counter
> (which I've created in tcp_sock)? Both locations are in the
> tcp_input.c.
>
> /* In tcp_fastretrans_alert() */
> if (flag & FLAG_ECE) {
> tp->prior_ssthresh = 0;
> tp->ecn_count += 1; // ECN counter
> }

This approach sounds good to me.

> or
>
> /* In tcp_enter_recovery() */
> if (!tcp_in_cwnd_reduction(sk)) {
> if (!ece_ack)
> tp->prior_ssthresh = tcp_current_ssthresh(sk);
> else
> tp->ecn_count += 1; // ECN counter
> tcp_init_cwnd_reduction(sk);
> }
> tcp_set_ca_state(sk, TCP_CA_Recovery);

This location would only count ECE marks we happened to get at the
moment we enter loss recovery.

neal

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