* Arjan van de Ven <[EMAIL PROTECTED]> wrote: > > That sounds like a big problem. > > it'll get way worse going forward. (but even on todays systems, the > tsc no longer represents frequency, but is some fixed clock totally > unrelated to cpu frequency)
X86_FEATURE_CONSTANT_TSC CPUs (all modern Intel CPUs) should be fine - we dont do any TSC frequency fixups for them. The loops_per_jiffy fixup looks like this: if (!(freq->flags & CPUFREQ_CONST_LOOPS)) cpu_data(freq->cpu).loops_per_jiffy = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new); i.e. X86_FEATURE_CONSTANT_TSC excluded. The sched_clock() scaling factor is modified like this: if (!(freq->flags & CPUFREQ_CONST_LOOPS)) { tsc_khz = cpu_khz; preempt_disable(); set_cyc2ns_scale(cpu_khz, smp_processor_id()); so here X86_FEATURE_CONSTANT_TSC is excluded again. So the whole frequency scaling issue will become a pure legacy issue only with time. Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/