From: Yuchung Cheng <ych...@google.com> Date: Fri, 27 Jan 2017 16:24:39 -0800
> Currently the retransmission stats are not incremented if the > retransmit fails locally. But we always increment the other packet > counters that track total packet/bytes sent. Awkwardly while we > don't count these failed retransmits in RETRANSSEGS, we do count > them in FAILEDRETRANS. > > If the qdisc is dropping many packets this could under-estimate > TCP retransmission rate substantially from both SNMP or per-socket > TCP_INFO stats. This patch changes this by always incrementing > retransmission stats on retransmission attempts and failures. > > Another motivation is to properly track retransmists in > SCM_TIMESTAMPING_OPT_STATS. Since SCM_TSTAMP_SCHED collection is > triggered in tcp_transmit_skb(), If tp->total_retrans is incremented > after the function, we'll always mis-count by the amount of the > latest retransmission. > > Signed-off-by: Yuchung Cheng <ych...@google.com> > Signed-off-by: Soheil Hassas Yeganeh <soh...@google.com> > Acked-by: Neal Cardwell <ncardw...@google.com> > Acked-by: Eric Dumazet <eduma...@google.com> Also applied, thank you.
