On 07/19/2018 04:44 PM, Thomas Gleixner wrote: > On Thu, 19 Jul 2018, Pavel Tatashin wrote: > >> On Thu, Jul 19, 2018 at 12:49 PM Pavel Tatashin >> <pasha.tatashin@xxxxxxxxxx> wrote: >>> >>>> So create two functions. native_...early..() and native....(). The early >>>> one does not contain the hpet/pmtimer stuff and it replaces the ops.pointer >>>> with the late one which contains all of it. >>> >>> Good idea. Actually, the late one will contain only hpet/pmtimer and I >>> will set it only if tsc frequency was not determined only. >> >> If we determined tsc early in boot using one of the quick methods: >> from cpuid/msr/quick_pit, can we assume that frequencies of all other >> CPUs will be determined the same way? Or do we still have to fallback >> to PIT/HPET/PMTIMER? I wondering if we support heterogeneous >> multi-socket platforms with different CPUs, because that the only >> platforms where I see such scenario is possible. > > The frequency for secondary CPUs is usually taken from the boot CPU and the > only reason why recalibration can happen is when the CPU does not have a > constant frequency TSC. > > For that case the quick PIT + hpet/pmtimer calibration bundle is > required. So yes, the early calibration might work with quick PIT (those > CPUs definitely do not have MSR/CPUID based calibration), but the > recalibration might fail the quick PIT calibration for various reasons. OK, good, I implemented with this in-mind. I will send out a new series shortly. Thank you, Pavel > > Thanks, > > tglx > -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
