On Mon, 2019-03-25 at 21:50 +0000, Phillips, Tony wrote: > So before commenting this output line out, this is what I see: > > Requeueing failed ESP send (work done 0, monitored 0): Resource temporarily unavailable > Requeueing failed ESP send (work done 0, monitored 1): Resource temporarily unavailable > Requeueing failed ESP send (work done 0, monitored 1): Resource temporarily unavailable > Requeueing failed ESP send (work done 1, monitored 0): Resource temporarily unavailable > Requeueing failed ESP send (work done 0, monitored 1): Resource temporarily unavailable > Requeueing failed ESP send (work done 1, monitored 0): Resource temporarily unavailable > Requeueing failed ESP send (work done 1, monitored 0): Resource temporarily unavailable > Requeueing failed ESP send (work done 0, monitored 1): Resource temporarily unavailable > Requeueing failed ESP send (work done 1, monitored 0): Resource temporarily unavailable > Requeueing failed ESP send (work done 0, monitored 1): Resource temporarily unavailable > Requeueing failed ESP send (work done 1, monitored 0): Resource temporarily unavailable > Requeueing failed ESP send (work done 1, monitored 0): Resource temporarily unavailable > Requeueing failed ESP send (work done 1, monitored 1): Resource temporarily unavailable > Requeueing failed ESP send (work done 1, monitored 0): Resource temporarily unavailable > Requeueing failed ESP send (work done 1, monitored 0): Resource temporarily unavailable > Requeueing failed ESP send (work done 1, monitored 0): Resource temporarily unavailable > Requeueing failed ESP send (work done 1, monitored 0): Resource temporarily unavailable > Requeueing failed ESP send (work done 0, monitored 0): Resource temporarily unavailable > Requeueing failed ESP send (work done 1, monitored 0): Resource temporarily unavailable > Requeueing failed ESP send (work done 1, monitored 0): Resource temporarily unavailable > Requeueing failed ESP send (work done 1, monitored 0): Resource temporarily unavailable > Requeueing failed ESP send (work done 1, monitored 0): Resource temporarily unavailable > Requeueing failed ESP send (work done 0, monitored 1): Resource temporarily unavailable OK, you should be getting 'monitored 0' when the packet first failed to send, then 'monitored 1' when the packet was already requeued once before, and the socket was being monitored for writeability. It does look like it *isn't* spinning in an attempt to write. Running with -vvv may confirm that, as it shows the packets being correctly sent. Or might just slow the whole thing down to the point where the interesting case isn't happening any more. > Performance was about the same as previous run (~20 MB/sec) > > Commenting out the vpn_progress() call actually helps quite a bit! > I'm getting runs now as fast as 50MB/sec. That makes sense. > Still see lots of the same IP/UDP errors, and TCP is fairly clean > with only 23 retransmitted segments after 10 "dd" runs. Yeah, the attempts to send UDP packets while the sendbuf is full are still reported, but those packets aren't *lost* any more; they're sent as soon as the socket will accept them. > Run times are rather variable -- with the bs=33554432, runs range > between 20MB/sec to sometimes 50MB/sec. > > If I increase it, the runs tend to narrow down closer to 20MB/sec all > the time. > > Making progress!! At this point, you appear to be sending packets to the UDP socket as fast as it will accept them. Now, maybe there's some issue with latency and fairness, and the ACKs coming back are somehow relevant here? But I wouldn't have expected that. Now would be the time to try reducing the MTU. I wonder if your UDP frames are getting fragmented in transit, making less optimal use of the physical bandwidth than they should? Are you able to capture the encrypted traffic on the ingress network next to the VPN server? Can you try running a UDP netperf over the VPN, to eliminate TCP issues? And in fact, try running the same UDP netperf over the underlying public network, with various packet sizes.
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