On 10/19/2010 03:47 AM, Dennis Jacobfeuerborn wrote: > On 10/19/2010 09:41 AM, Pasi Kärkkäinen wrote: >> >> It's because of the x86_64 architecture, afaik. >> >> There was some good technical explananation about it, >> but I can't remember the url now. > In that case I'll have to call this advice extremely bogus and you probably > should refrain from passing it on. The only way I can see this being true > is some weird corner case. There appear to be some interactions with the Intel VT-d processor features. http://www.xen.org/files/xensummit_intel09/xensummit2009_IOVirtPerf.pdf If I understand that paper correctly, HVM+VT-d outperforms PV by quite a lot (if you have VT-d support on your system). -- Benjamin Franz