From: Eric Dumazet <eric.duma...@gmail.com>
Date: Tue, 20 Sep 2016 22:45:58 -0700
> From: Eric Dumazet <eduma...@google.com>
> We saw sch_fq drops caused by the per flow limit of 100 packets and TCP
> when dealing with large cwnd and bursts of retransmits.
> Even after increasing the limit to 1000, and even after commit
> 10d3be569243 ("tcp-tso: do not split TSO packets at retransmit time"),
> we can still have these drops.
> Under certain conditions, TCP can spend a considerable amount of
> time queuing thousands of skbs in a single tcp_xmit_retransmit_queue()
> invocation, incurring latency spikes and stalls of other softirq
> This patch implements TSQ for retransmits, limiting number of packets
> and giving more chance for scheduling packets in both ways.
> Signed-off-by: Eric Dumazet <eduma...@google.com>
> Signed-off-by: Yuchung Cheng <ych...@google.com>
> Signed-off-by: Neal Cardwell <ncardw...@google.com>