Major performance/stability regression in virtio network drivers between 9.2-RELEASE and 10.0-RC5

[Bryan Venteicher]

----- Original Message -----
> Hello Bryan:
> 
> I'm not using DHCP on that interface.
> 
> I'll throw out there this only appears to happen with receive, I still get
> good performance on send.
> 


After a few off list exchanges, the difference between 9.2 and 10.0 was
due to LRO not being enabled. The driver in 10.0 (rightly so) does not
default to turning LRO on when it is available. 

There does seem to be some timer oddities, but that was not an issue on
Eric's system.


> client:
> $ iperf -c 192.168.100.5 -r -t 20
> 
> freebsd server:
> 
> $ sudo iperf -s
> ------------------------------------------------------------
> Server listening on TCP port 5001
> TCP window size: 64.0 KByte (default)
> ------------------------------------------------------------
> [  4] local 192.168.100.5 port 5001 connected with 192.168.100.6 port 43573
> [ ID] Interval       Transfer     Bandwidth
> [  4]  0.0-20.0 sec  7.00 GBytes  3.01 Gbits/sec ******** slow
> ------------------------------------------------------------
> Client connecting to 192.168.100.6, TCP port 5001
> TCP window size: 40.5 KByte (default)
> ------------------------------------------------------------
> [  4] local 192.168.100.5 port 35167 connected with 192.168.100.6 port 5001
> Waiting for server threads to complete. Interrupt again to force quit.
> [  4]  0.0-20.0 sec  46.5 GBytes  20.0 Gbits/sec ******** expected
>