10G performance regression / difference cxl and ix RELENG11 vs HEAD

[Navdeep Parhar]

On 10/12/18 8:37 AM, Mike Tancsa wrote:
> I was doing a quick iperf test with  r339328 GENERIC-NODEBUG  amd64, and
> noticed  I can no longer saturate a 10G nic with iperf3.  I tried first
> with the ix adapter, but was not sure if it was the driver or not. I
> tried as well with a Chelsio and got similar numbers.
> 
> # iperf3 -c 192.168.242.3
> Connecting to host 192.168.242.3, port 5201
> [  5] local 192.168.242.2 port 50474 connected to 192.168.242.3 port 5201
> [ ID] Interval           Transfer     Bitrate         Retr  Cwnd
> [  5]   0.00-1.00   sec   997 MBytes  8.36 Gbits/sec  717    175
> KBytes      
> [  5]   1.00-2.00   sec   975 MBytes  8.18 Gbits/sec  668   41.1
> KBytes      
> [  5]   2.00-3.00   sec   880 MBytes  7.38 Gbits/sec  846   25.6
> KBytes      
> [  5]   3.00-4.00   sec   523 MBytes  4.39 Gbits/sec  802   59.8
> KBytes      
> [  5]   4.00-5.00   sec   520 MBytes  4.36 Gbits/sec  882   48.4
> KBytes      
> [  5]   5.00-6.00   sec   543 MBytes  4.55 Gbits/sec  838   56.9
> KBytes      
> [  5]   6.00-7.00   sec   556 MBytes  4.66 Gbits/sec  850   11.4
> KBytes      
> [  5]   7.00-8.00   sec   538 MBytes  4.51 Gbits/sec  795   39.9
> KBytes      
> [  5]   8.00-9.00   sec   540 MBytes  4.53 Gbits/sec  853   57.0
> KBytes      
> [  5]   9.00-10.00  sec   503 MBytes  4.22 Gbits/sec  814   59.8
> KBytes      
> - - - - - - - - - - - - - - - - - - - - - - - - -
> [ ID] Interval           Transfer     Bitrate         Retr
> [  5]   0.00-10.00  sec  6.42 GBytes  5.52 Gbits/sec  8065            
> sender
> [  5]   0.00-10.00  sec  6.42 GBytes  5.52 Gbits/sec                 
> receiver

The number of retries (the "Retr" column) should have been 0 in a
controlled test like this.  Is this the default stack with all default
parameters or have you tuned TCP and/or sockets in any way?

Regards,
Navdeep