On Wed, Feb 08, 2012 at 01:56:46PM -0200, Marcelo Tosatti wrote: > On Wed, Feb 08, 2012 at 04:18:48PM +0100, Joerg Roedel wrote: > > This is not going to work when tsc-scaling is enabled. The > > adjust_tsc_offset_host() function just scales the offset the same way > > the tsc is scaled. But that is broken because the tsc-offset is applied > > _after_ the tsc-ratio by scaling hardware. So to get the desired > > tsc-value in the guest the offset needs to be scaled in the opposite > > direction as the tsc itself. This is rather complicated to implement. > > By saying that "tsc-offset is applied _after_ the tsc-ratio by scaling > hardware" you mean that guest tsc is calculated as > > tsc = host_tsc_value * tsc_ratio > tsc += tsc_offset > > ? > > If so, that means the tsc_offset must be scaled to guest tsc units. > > Which is what both adjust_tsc_offset(host=true) and compute_tsc_offset() > do. > > What am i missing here? Nothing. You are right, bad math on my side. Joerg -- AMD Operating System Research Center Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632 -- 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
