On 24/04/2015 03:16, Zhang, Yang Z wrote: >> This is interesting since previous measurements on KVM have had >> the exact opposite results. I think we need to understand this a >> lot more. > > What I can tell is that vmexit is heavy. So it is reasonable to see > the improvement under some cases, especially kernel is using eager > FPU now which means each schedule may trigger a vmexit. On the other hand vmexit is lighter and lighter on newer processors; a Sandy Bridge has less than half the vmexit cost of a Core 2 (IIRC 1000 vs. 2500 clock cycles approximately). Also, measurement were done on Westmere but Sandy Bridge is the first processor to have XSAVEOPT and thus use eager FPU. Paolo -- 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
