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Re: [XenARM] [Android-virt] [ANNOUNCE] Xvisor ARM better than KVM ARM in CPU virtualization

On Sat, May 5, 2012 at 7:54 PM, Anup Patel <anup@xxxxxxxxxxxxxx> 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.

The previous announcement only proves that Xvisor ARM is relatively better than KVM ARM.

Regards,
--Anup

On Sat, May 5, 2012 at 3:36 PM, Peter Maydell <peter.maydell@xxxxxxxxxx> wrote:

2012/5/5 Anup Patel <anup@xxxxxxxxxxxxxx>:

> 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

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