| Message ID | 20110310165328.811355927@vyatta.com |
|---|---|
| State | Superseded, archived |
| Delegated to: | David Miller |
| Headers | show |
--- a/net/ipv4/tcp_input.c 2011-03-08 11:11:26.093183654 -0800 +++ b/net/ipv4/tcp_input.c 2011-03-08 11:11:46.641404939 -0800 @@ -3350,7 +3350,7 @@ static int tcp_clean_rtx_queue(struct so net_invalid_timestamp())) rtt_us = ktime_us_delta(ktime_get_real(), last_ackt); - else if (ca_seq_rtt > 0) + else if (ca_seq_rtt >= 0) rtt_us = jiffies_to_usecs(ca_seq_rtt); }
In the congestion control interface, the callback for each ACK includes an estimated round trip time in microseconds. Some algorithms need high resolution (Vegas style) but most only need jiffie resolution. If RTT is not accurate (like a retransmission) -1 is used as a flag value. When doing coarse resolution if RTT is less than a a jiffie then 0 should be returned rather than no estimate. Otherwise algorithms that expect good ack's to trigger slow start (like CUBIC Hystart) will be confused. Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> -- 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