On 2011-05-12 15:11, Joerg Roedel wrote: > On Thu, May 12, 2011 at 11:47:51AM +0200, Jan Kiszka wrote: >> On 2011-05-12 11:33, Joerg Roedel wrote: > >>> Anyway, I thought about a paravirt-approach instead of implementing a >>> real PMU... But there are certainly good reasons for both. >> >> Paravirt is taking away the pressure from CPU vendors to do their virt >> extensions properly - and doesn't help with unmodifiable OSes. > > Seriously, I think such decisions should be technical only and not > political like that. The losers of such political decisions are always > the users because they don't get useful features that are technical > possible. Paravirt remains a workaround, useful until hardware provides a solution for all guests, and that often in an even more efficient way (like for MMU virtualization). We do not need to block a PV-PMU for Linux guests (or other OSes that want to adopt to it), but that will not be a solution for the problem, that's my point. A PV-PMU may even be useful to demonstrate usefulness of a virtual PMU the CPU vendors (if they aren't aware of this yet). Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
