On Wed, 2017-01-25 at 06:39 -0800, Eric Dumazet wrote: > On Wed, 2017-01-25 at 09:26 -0500, Josef Bacik wrote: > > > > > Nope ftrace isn't broken, I'm just dumb, the space is being > > reclaimed > > by sk_wmem_free_skb(). So I guess I need to figure out why I stop > > getting ACK's from the other side of the loopback. Thanks, > ss -temoi dst 127.0.0.1 > > Might give you some hints, like packets being dropped. > > ACK can be delayed if the reader is slow to consume bytes. >
Yup looks like I'm getting packet loss for some reason, but the application is sitting there in recvmsg, so it's not hung and definitely available for receiving new packets. ESTAB 0 4124232 ::1:34044 ::1:nbd t imer:(on,1min38sec,9) ino:20067 sk:8 <-> skmem:(r0,rb6291456,t0,tb4194304,f1720,w4204872,o0,bl0) ts sack cubic wscale:7,7 rto:102912 backoff:9 rtt:0.084/0.038 ato:40 mss:65464 cwnd:1 ssthresh:18 bytes_acked:71964077253 bytes_received:68804409996 segs_out:3882829 segs_in:4092731 send 6234.7Mbps lastsnd:4336 lastrcv:111289 lastack:111299 unacked:28 retrans:1/4277 lost:28 reordering:60 rcv_rtt:1.875 rcv_space:1315136 ESTAB 0 0 ::1:nbd ::1:34044 ti mer:(keepalive,109min,0) ino:19396 sk:2 <-> skmem:(r0,rb6291456,t0,tb2626560,f0,w0,o0,bl0) ts sack cubic wscale:7,7 rto:201 rtt:0.279/0.16 ato:40 mss:65464 cwnd:16 ssthresh:9 bytes_acked:68804409996 bytes_received:71964077252 segs_out:4092730 segs_in:3882792 send 30033.7Mbps lastsnd:111286 lastrcv:111307 lastack:111286 retrans:0/3113 reordering:26 rcv_rtt:1 rcv_space:4782816 I traced tcp_enter_loss() and once things stop moving that starts firing. That's all I have so far, been busy with other things but I'm devoting my full attention to this now. Thanks, Josef
