ARM public key benchmark

[Niels Möller]

Richard Henderson <rth at twiddle.net> writes:

> Looking around the web it seems that what most folks do is write a
> minimal kernel module that toggles the bit that allows userspace
> access to the cycle counter MSRs.

I've seen some code snippets to do that too. I have a dual core system;
one known issue when I tried searching for this some month ago was that
it set the needed register bits only on the core on which the kernel
module happened to be loaded. So that seems like a partial solution
only. And I have no idea about how to write a Linux kernel module that
makes a certain function be executed on all available cores; if I can
find out, I'll definitely try that.

> I havn't fiddled with this myself, because the A15 includes a real
> high-resolution clock, which is accessed via CLOCK_MONOTONIC.

On my system, both CLOCK_MONOTONIC and CLOCK_PROCESS_CPUTIME_ID seem to
tick in units of roughly 30 us. Which is disappointingly poor
resolution.

Regards,
/Niels

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