Re: Slow xennet, occasionally

[Stephen Borrill <netbsd%precedence.co.uk@localhost>]

> I'm occasionally seeing a slow xennet is domU:
>
>  Throughput is perhaps 20% of normal, and pings are about 5 times
>  higher.
>
>  When the problem occurs, it's always present from boot.
>
>  When the first xennet is slow at boot time, I can add a second xennet
> and it will usually be fast.
>
>  Usually one reboot will fix the problem.
>
>  I've seen this on NetBSD 6 and 7.

I'm seeing this pretty consistently on NetBSD 7, NetBSD 5 is fine. dom0 is 
XenServer, domUs are on same host. Rebooting makes no difference. This is 
IMHO a serious problem.

NetBSD-5 domU -> physical host:
NETIO - Network Throughput Benchmark, Version 1.26
(C) 1997-2005 Kai Uwe Rommel

TCP connection established.
Packet size  1k bytes:  103375 KByte/s Tx,  81319 KByte/s Rx.
Packet size  2k bytes:  107507 KByte/s Tx,  96727 KByte/s Rx.
Packet size  4k bytes:  110407 KByte/s Tx,  94854 KByte/s Rx.
Packet size  8k bytes:  111326 KByte/s Tx,  108494 KByte/s Rx.
Packet size 16k bytes:  111244 KByte/s Tx,  107681 KByte/s Rx.
Packet size 32k bytes:  111291 KByte/s Tx,  99243 KByte/s Rx.
Done.

NetBSD-7 domU -> physical host:
NETIO - Network Throughput Benchmark, Version 1.26
(C) 1997-2005 Kai Uwe Rommel

TCP connection established.
Packet size  1k bytes:  9641 KByte/s Tx,  9890 KByte/s Rx.
Packet size  2k bytes:  11940 KByte/s Tx,  11718 KByte/s Rx.
Packet size  4k bytes:  11529 KByte/s Tx,  12110 KByte/s Rx.
Packet size  8k bytes:  11485 KByte/s Tx,  12266 KByte/s Rx.
Packet size 16k bytes:  11435 KByte/s Tx,  12051 KByte/s Rx.
Packet size 32k bytes:  11501 KByte/s Tx,  12287 KByte/s Rx.
Done.