On Thu, Feb 8, 2018 at 9:41 PM, Lynch, Nathan <nathan_ly...@mentor.com> wrote:
>> I commented the device tree reading property:
>> arm,cpu-registers-not-fw-configured , from the arch/arm/kernel/vdso.c
> Don't do that, please. The presence of that property indicates that the 
> counter is not suitable for use by the OS. There is nothing we can do in 
> Linux to make the VDSO useful on this system; that is why it gets disabled at 
> runtime.
> The timing measurements you get are likely tainted by garbage results from 
> the VDSO itself.

OK thank you for your feedback.

But, we wanted to know, why vdso call timing is very high here. What
does this timing indicates?
gettimeofday: vdso: 4171 nsec/call

1) How to decide whether to enable or disable VDSO in the system, if
its not suitable.
Because in a VDSO enabled system, when we use gettimeofday API, we see
that its not falling back to the systemically, but may rather return a
garbage value from vdso itself.
If that is the case, shall we disable CONFIG_VDSO itself or keep it as it is ?

Please suggest your opinion.

2) Can you list down 1-2 arm 32-bit board, where VDSO can work perfectly ?

This will be really helpful for us to take some decision.

Thank You!

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