| Message ID | 20240815001718.2845791-4-mrzhang97@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | tcp_cubic: fix to achieve at least the same throughput as Reno | expand |
diff --git a/net/ipv4/tcp_cubic.c b/net/ipv4/tcp_cubic.c index 7bc6db82de66..a1467f99a233 100644 --- a/net/ipv4/tcp_cubic.c +++ b/net/ipv4/tcp_cubic.c @@ -315,8 +315,11 @@ static inline void bictcp_update(struct bictcp *ca, u32 cwnd, u32 acked) ca->tcp_cwnd++; } - if (ca->tcp_cwnd > cwnd) { /* if bic is slower than tcp */ - delta = ca->tcp_cwnd - cwnd; + /* Reno cwnd one RTT in the future */ + u32 tcp_cwnd_next_rtt = ca->tcp_cwnd + (ca->ack_cnt + cwnd) / delta; + + if (tcp_cwnd_next_rtt > cwnd) { /* if bic is slower than Reno */ + delta = tcp_cwnd_next_rtt - cwnd; max_cnt = cwnd / delta; if (ca->cnt > max_cnt) ca->cnt = max_cnt;
The original code estimates RENO snd_cwnd using the estimated RENO snd_cwnd at the current time (i.e., tcp_cwnd). The patched code estimates RENO snd_cwnd using the estimated RENO snd_cwnd after one RTT (i.e., tcp_cwnd_next_rtt), because ca->cnt is used to increase snd_cwnd for the next RTT. Thanks Mingrui, and Lisong Fixes: 856873e362b0 ("tcp_cubic: fix to use emulated Reno cwnd one RTT in the future") Signed-off-by: Mingrui Zhang <mrzhang97@gmail.com> Signed-off-by: Lisong Xu <xu@unl.edu> --- net/ipv4/tcp_cubic.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)