Re: MTIME update frequency

Ved Shanbhogue

On Sun, Nov 21, 2021 at 11:34:04AM -0800, Greg Favor wrote:

Based on above points, I still think mandating fixed MTIME resolution is
desirable for OS-A platforms and this has nothing to do with how
timebase-frequency is discovered (i.e. DT/ACPI).
If we do want to fix the resolution then the 10ns is too coarse. I suggest
we make it at least 1ns to address the requirements of systems many of us
are building. With 10ns resolution it will not be competitive against ARM
systems that as you noted have fixed resolution to 1ns or x86 where TSC
operates at P0 frequency.
Note that ARM SBSA did not mandate a 1 GHz update rate; it only mandated a
1ns resolution - and explicitly acknowledged that updates may be at a lower
rate using counter scaling.
Absolutely. I was only suggesting a 1ns resolution and not a 1ns update rate.


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