Re: [Xen-devel] [PATCH V13 0/7] Mem_access for ARM

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Fri, 2015-03-06 at 22:24 +0100, Tamas K Lengyel wrote:
> The ARM virtualization extension provides 2-stage paging, a similar mechanisms
> to Intel's EPT, which can be used to trace the memory accesses performed by
> the guest systems. This series sets up the necessary infrastructure in the
> ARM code to deliver the event on R/W/X traps. Finally, we turn on the
> compilation of mem_access and mem_event on ARM and perform the necessary
> changes to the tools side.
> 
> This version of the series is based on master and each patch in the series has
> been compile tested on both ARM and x86.
> 
> The following benchmarks have been completed on an Arndale board before and
> after applying this entire series in dom0, which had 2 vCPUs available
> pinned. No regressions are evident based on these benchmarks.
> 
>                         | f0ffd60 | AFTER
> --------------------------------------------
> hackbench               | 1.604   | 1.618
> hackbench -pT           | 1.170   | 1.126
> hardinfo CPU Blowfish   | 43.252  | 43.323   
> hardinfo CPU CryptoHash | 40.935  | 40.893   
> hardinfo CPU Fibonacci  | 10.358  | 10.360
> hardinfo CPU N-Queens   | 25.773  | 25.894   
> hardinfo FPU FFT        | 20.332  | 20.325
> hardinfo FPU Raytracing | 73.017  | 73.104   

Thanks for these, they are very reassuring.

More for curiosities sake than anything else: Do you have any figures
for the overhead of enabling memaccess?



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