On Fri, Aug 15, 2014 at 09:08:50AM -0400, Ashwin Chaugule wrote: > If the OS only looks at Highest, Lowest, Delivered registers and only > writes to Desired, then we're not really any different than how we do > things today in the CPUFreq layer. The thing is; we're already struggling to make 'sense' of x86 as it stands today. And it looks like this CPPC stuff makes the behaviour even less certain. > Or even in the case of > intel_pstate, if you map Desired to PERF_CTL and get value of > Delivered by using aperf/mperf ratios (as my experimental driver > does), then we can still maintain the existing system performance. It > seems like if an OS can make use of the additional information then it > should be net win for overall power savings and performance > enhancement. Also, using the CPPC descriptors, we should be able to > have one driver across X86 and ARM64. (possibly others too.) Yikes, so aaargh64 will go do creative power management too? And worse; it will go do ACPI? Welcome to the world of guaranteed BIOS fail :-(
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