GPVPV xif benchmarks

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

Measured on Windows 2008 SP1 32-bit using TCP with netio and the netio 
server on the dom0 (i.e. connection over bridge(4)).

HVM:
Packet size  1k bytes:  14453 KBytes/s Tx,  65130 KByte/s Rx.
Packet size  2k bytes:  14764 KBytes/s Tx,  68407 KByte/s Rx.
Packet size  4k bytes:  23051 KBytes/s Tx,  62768 KByte/s Rx.
Packet size  8k bytes:  25602 KBytes/s Tx,  68443 KByte/s Rx.
Packet size 16k bytes:  34354 KBytes/s Tx,  67482 KByte/s Rx.
Packet size 32k bytes:  43223 KBytes/s Tx,  65291 KByte/s Rx.
15-20% CPU usage by qemu-dm and 5% CPU by netio.

PV:
Packet size  1k bytes:  75744 KBytes/s Tx,  85640 KByte/s Rx.
Packet size  2k bytes: 152205 KBytes/s Tx, 125223 KByte/s Rx.
Packet size  4k bytes: 105095 KBytes/s Tx,  79333 KByte/s Rx.
Packet size  8k bytes: 164465 KBytes/s Tx, 130303 KByte/s Rx.
Packet size 16k bytes: 179355 KBytes/s Tx, 160675 KByte/s Rx.
Packet size 32k bytes: 206289 KBytes/s Tx, 147641 KByte/s Rx.
<0.5% CPU usage by qemu-dm and 40-50% CPU usage by netio.

I repeated the PV test later and found the same pattern (dip with 4k 
packet size).

--
Stephen