On Wed, Oct 11, 2023 at 10:31 PM Haiyang Zhang <haiyangz@xxxxxxxxxxxxx> wrote: > > TCP pingpong threshold is 1 by default. But some applications, like SQL DB > may prefer a higher pingpong threshold to activate delayed acks in quick > ack mode for better performance. > ... > > diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c > index f207712eece1..7d0fe76d56ef 100644 > --- a/net/ipv4/tcp_output.c > +++ b/net/ipv4/tcp_output.c > @@ -170,10 +170,10 @@ static void tcp_event_data_sent(struct tcp_sock *tp, > tp->lsndtime = now; > > /* If it is a reply for ato after last received > - * packet, enter pingpong mode. > + * packet, increase pingpong count. > */ > if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato) > - inet_csk_enter_pingpong_mode(sk); > + inet_csk_inc_pingpong_cnt(sk); > } > > /* Account for an ACK we sent. */ OK, but I do not think we solved the fundamental problem of using jiffies for this heuristic, especially for HZ=100 or HZ=250 builds. Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
