On Sat, 5 May 2012 15:24:26 +0100 Anup Patel <anup at brainfault.org> wrote: > Hi PMM, > > I agree we cannot predict real world performance based on performance on ARM fast models but if system A is performing better than system B no ARM fast model or QEMU then in real world system A will perform better than system B. Of-course in real world scale of difference in performance between system A and system B will differ. > You may want to re-read Peter's email, and consider that the model doesn't represent the micro-architecture. A code sequence X can be faster than a sequence Y on the model, and the opposite on real hardware. The same is equally valid on two different implementation of the same architecture (Cortex-A7 vs Cortex-A15, for example). > The previous announcement only proves that Xvisor ARM is relatively better than KVM ARM. On the Fast Model. M. > On Sat, May 5, 2012 at 3:36 PM, Peter Maydell <peter.maydell at linaro.org<mailto:peter.maydell at linaro.org>> wrote: > 2012/5/5 Anup Patel <anup at brainfault.org<mailto:anup at brainfault.org>>: > > This announcement is to show an apple to apple performance comparison > > between Xvisor ARM and KVM ARM running on VExpress-A15 Fast Model. > > I would strongly caution against trying to do any performance/timing > type tests if you're still running on the ARM Fast Model -- they are > not representative of performance characteristics on hardware > and you really can't draw any conclusions about real world > performance by timing things on a model. It's quite easy to get > into a situation where all you're measuring is "does my code happen > to do a lot of some perfectly reasonable operation which happens > to be hard and slow to implement for the model?". > > (Also, KVM for ARM is still under development and we haven't > yet made several of the obvious performance improvements like > in-kernel irqchip and timer support, so it's not really a very > useful thing to compare against yet.) > > -- PMM > -- I'm the slime oozin' out from your TV set...
