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! Pintu