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That's where > >> SD_ASYM_PACKING originated from. > > > > Yep, I'm actually experimenting with a patch that mimics the Power7 and it > > seems to work. :) But I'm using a quirk to detect the particular CPU > > implementation to set SD_ASYM_PACKING on the SMT domain and assign a higher > > arch_asym_cpu_priority() to the first sibling, which is not the best... > > > > So I'm checking with the firmware folks whether they can expose the relative SMT > > thread priority explicitly, so that the kernel can discover the asymmetry and > > the preferred sibling, instead of relying on CPU type and enumeration order > > (considering that there are also multiple SMT configurations that can alter this > > asymmetry... it's not just SMT on/off). > > Thanks for the explanation, interesting... > So maybe we can fold the entire highest_perf thing into that, too, so you end up > just with SD_ASYM_PACKING and not > SD_ASYM_PACKING (for SMT sibling asymmetry)+CAS(for highest_perf core asymmetry), > I think that would be a lot cleaner. I think so. I need to try combining this with your SD_ASYM_PACKING series. This is what I’m currently experimenting with, if you're curious (still WIP): git://git.kernel.org/pub/scm/linux/kernel/git/arighi/linux.git vr-smt Thanks, -Andrea