Re: [PATCH net-next] tcp: use SACK RTTs for CC
From: Yuchung Cheng <hidden>
Date: 2015-01-30 17:22:26
On Thu, Jan 29, 2015 at 11:08 AM, Kenneth Klette Jonassen [off-list ref] wrote:
Current behavior only passes RTTs from sequentially acked data to CC. If sender gets a combined ACK for segment 1 and SACK for segment 3, then the computed RTT for CC is the time between sending segment 1 and receiving SACK for segment 3.
since segment 3 is sent after segment 1, sack_rtt_us <= ca_seq_rtt so taking a min is not necessary?
quoted hunk ↗ jump to hunk
Pass the minimum computed RTT from any acked data to CC, i.e. time between sending segment 3 and receiving SACK for segment 3. Signed-off-by: Kenneth Klette Jonassen <redacted> --- net/ipv4/tcp_input.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 71fb37c..ed11931 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c@@ -3183,8 +3183,10 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets, tp->fackets_out -= min(pkts_acked, tp->fackets_out); - if (ca_ops->pkts_acked) - ca_ops->pkts_acked(sk, pkts_acked, ca_seq_rtt_us); + if (ca_ops->pkts_acked) { + long rtt_us = min_t(ulong, ca_seq_rtt_us, sack_rtt_us); + ca_ops->pkts_acked(sk, pkts_acked, rtt_us); + } } else if (skb && rtt_update && sack_rtt_us >= 0 && sack_rtt_us > skb_mstamp_us_delta(&now, &skb->skb_mstamp)) { --1.9.1 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html