Benchmark Armv8 VMM

[Chris Hofer]

Hi,

to measure the performance overhead of the Armv8 Genode VMM, I ran some 
benchmarks (cyclictest and lmbench). I compared it against a native 
Linux installation on the Imx8-evk board (same kernel version). For some 
measurements (for example fork + executing /bin/sh from lmbench), I 
observe counter-intuitive results in the sense that the virtualized 
version runs *faster* than the native one (Vm 1,1ms vs. native 2,5ms).

My understanding is, that the virtual timer offset (cntvoff_el2) is not 
used and thus, the guest sees wall clock time. I would expect that the 
virtualization incurs an overhead and this overhead manifests itself in 
longer (wall clock) time measurements.

Do you have any explanation for this or give me a hint on how to confirm 
correctness of measurements?


Best,

Chris

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