Messages in this thread | | | Date | Wed, 26 Jul 2017 13:56:10 -0700 | From | Saravana Kannan <> | Subject | Re: [Eas-dev] [PATCH V3 2/3] cpufreq: schedutil: Process remote callback for shared policies |
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On 07/20/2017 05:22 AM, Peter Zijlstra wrote: > So the typical implementation of fast switching we're thinking of is the > CPU writing the DVFS request into a machine register. Now machine > registers are typically per logical CPU.
Writing to a memory addressable register. AFAIK, ARM has no support for a machine register for DVFS request. So, even if any ARM licensee wants to add one, it won't be possible.
Also, even if we have an ARM CPU with a machine register, rejecting a valid frequency switch just because it happened to come on a different CPU seem silly (you can have a huge performance hit due to that). A much better solution is to just make an IPI to the right CPU and execute the machine register write on the right CPU.
-Saravana
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