[Mono-dev] Performance problems on ARM/linux

Martin Fuzzey mfuzzey at parkeon.com
Wed Apr 15 13:52:36 EDT 2009

Rodrigo Kumpera wrote:
> Which FP mode your cpu/linux support? FPA, VFP or soft-float?
> ARM_FPU_NONE enables soft-float mode, which is super slow compared
> to any hardware.
I'm using build option ARM_FPU_FPA however the hardware itself doesn't
have a FPU so the kernel is doing the emulation.
I think ARM_FPU_NONE uses a pure userspace implementation which should
be faster than trapping illegal instructions and emulating in the
kernel. Unfortunately that doesn't work as I indicated  (problem with
floats but not doubles).

That said I don't think the performance problems stem from FP - it's not
a number crunching app. In fact the application doesn't directly use FP
at all though some of the system libraries (like hastable) do.


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