Memory bandwidth degradation of Armv8 virtualization
chris-hofer at zehha.de
Mon Jun 8 22:33:49 CEST 2020
I'm currently measuring the memory bandwidth of the Genode Armv8 Linux
Virtualization by running tinymembench and lmbench's memory
bandwidth. On the NXP I.mx8 the results of both benchmarks showed a
degradation of roughly 25 to 35 percent (depending on the exact
benchmark) compared to native Linux.
I tried to ensure comparability with the native setup by disabling in
native Linux all but one core and fixing this core's frequency to 1 GHz
(which should be the frequency Genode uses). Both setups use the same
To improve the performance I played with the register values controlling
caching (clear HCR_EL2.CD - enable S2 Data cacheability; VTCR_EL2.Irgn0
and VTCR_EL2.Orgn0 respectively set to b11 - set Normal memory,
Inner/Outer Write-Back Read-allocate No Write-Allocate Cachable).
However, this had no significant effect.
What's your opinion on that? Based on your experience with
virtualization, do these values surprise you or is this an expected
All the best,
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