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These small variations, typically due to silicon > >>> binning, are reflected in arch_scale_cpu_capacity() and end up being > >>> interpreted as real capacity asymmetry. > >>> > >>> As a result, the scheduler incorrectly enables SD_ASYM_CPUCAPACITY, > >>> triggering asymmetry-specific behaviors, even though all CPUs have > >>> comparable performance. > >>> > >>> Prevent this by treating CPU capacities within 20% of the maximum value > >> > >> 20% is a bit high, my snapdragon rb5 has a mid CPU with a capacity of > >> 871 but we still want to keep them different > >> > >> Why would 5% not be enough? > > > > I've also used 5%, or rather the existing capacity_greater() macro. > > Also, given that this patch even mentions this as "noise" one might ask > why the firmware wouldn't force-equalise this. I think it's reasonable to consider that as "noise" from a scheduler perspective, but from a hardware/firmware point of view I don't have strong arguments to propose equalizing the highest_perf values. At the end, at least in my case, it seems all compliant with the ACPI/CPPC specs and suggesting to equalize them because "the kernel doesn't handle it well" doesn't seem like a solid motivation... > Anyway let me finally send out those asympacking patches which would make > that issue obsolete because we actually make use of the highest_perf > information from the firmware. Looking forward to that. :) Thanks, -Andrea