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Re: [XenARM] [Android-virt] [ANNOUNCE] Xvisor ARM better than KVM ARM in CPU virtualization
Hi Marc,
We must understand that the claimed best performing hypervisor today is a complete monolithic hypervisor (i.e. VMware ESX server). The Xvisor vision is to have GPLv2 monolithic hypervisor. Our point is that KVM approach to virtualization is not optimal one and you will end-up putting more and more things in-kernel.
Also can you give example of a code sequence which is faster on model and slower in real world. As far as I know ARM fast models are internally TLM based models and If a TLM based model is emulating a timer chip of X clock then it is quite precise X clock. Ofcourse CPU emulation and computation power will be less compared to real world. To see this behaviour try to boot linux on Fast model or QEMU and leave it for hours and come back see the time elapsed, you will definitely see same amount of time elapsed as real world.
The results in the announcemnt are not baseless we have quite amount reasons to believe Xvisor ARM will perform better than KVM ARM in real-world too.
Regards,
Anup Patel
On Sat, May 5, 2012 at 8:44 PM, Marc Zyngier <marc.zyngier@xxxxxxx> wrote:
On Sat, 5 May 2012 15:31:36 +0100
> Also in my-view even if we have in-kernel emulation of irqchip and timer still Xvisor ARM will be performing better than KVM ARM because amount of code path traversed in KVM ARM will always be more.
>
> (Please note my-view about in-kernel emulation is totally based on code flow comparison of Xvisor ARM emulation and possible KVM ARM in-kernel emulation)
>
Sweet. Can I borrow your crystal ball?
M.
> On Sat, May 5, 2012 at 7:54 PM, Anup Patel < anup@xxxxxxxxxxxxxx<mailto: 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
>
>
> 2012/5/5 Anup Patel <anup@xxxxxxxxxxxxxx<mailto: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
>
>
--
I'm the slime oozin' out from your TV set...
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