On Thu, Dec 15, 2011 at 08:29:11PM +0000, Russell King - ARM Linux wrote: > On Thu, Dec 15, 2011 at 07:16:35PM +0800, Richard Zhao wrote: > > +#ifdef CONFIG_SMP > > + /* loops_per_jiffy is not updated by the cpufreq core for SMP systems. > > + * So update it for all CPUs. > > + */ > > + for_each_possible_cpu(cpu) > > + per_cpu(cpu_data, cpu).loops_per_jiffy = > > + cpufreq_scale(per_cpu(cpu_data, cpu).loops_per_jiffy, > > + freqs.old, freqs.new); > > NAK. If you think this is a good solution, you're very wrong. If this > is what's in the core cpufreq code, then it too is very broken. > > I've seen this exact method result in the loops_per_jiffy being totally > buggered over time by the constant scaling up and down. The only way > to do this _sensibly_ is to record the _initial_ loops_per_jiffy and > _inital_ frequency, and scale from that. > > That way you get consistent results irrespective of the scalings you > do over time, rather than something which continually deteriorates with > every frequency change. Thanks for your comments. I'll recalculate loops_per_jiffy always based on boot up values. Thanks Richard > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
