Messages in this thread | | | Date | Fri, 5 Aug 2011 12:46:35 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH v2] x86: Reduce clock calibration time during slave cpu startup |
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* Jack Steiner <steiner@sgi.com> wrote:
> +/* > + * Check if another cpu is in the same socket and has already been calibrated. > + * If found, use the previous value. This assumes all cores in the same physical > + * socket have the same core frequency. > + > +unsigned long __cpuinit calibrate_delay_is_known(void) > +{ > + int i, cpu = smp_processor_id(); > + > + if (!tsc_disabled && !cpu_has(&cpu_data(cpu), X86_FEATURE_CONSTANT_TSC)) > + return 0; > + > + for_each_online_cpu(i) > + if (cpu_data(i).phys_proc_id == cpu_data(cpu).phys_proc_id) > + return cpu_data(i).loops_per_jiffy;
Hm, why do we have to make such an assumption? Cannot we query the core frequency?
Thanks,
Ingo
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