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
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