On Jun 16, 2010, at 4:05 PM, Len Brown <lenb@xxxxxxxxxx> wrote: > Create /sys/power/policy_preference, giving user-space > the ability to express its preference for kernel based > power vs. performance decisions in a single place. > > This gives kernel sub-systems and drivers a central place > to discover this system-wide policy preference. > It also allows user-space to not have to be updated > every time a sub-system or driver adds a new power/perf knob. I would prefer documenting all the current knobs and adding them to pm- utils so that pm-powersave knows about and can manage them. Once that is done, creating arbitrary powersave levels should be fairly simple. > policy_preference has 5 levels, from max_performance > through max_powersave. Here is how 4 parts of the kernel > might respond to those 5 levels: > > max_performance (unwilling to sacrifice any performance) > scheduler: default (optimized for performance) > cpuidle: disable all C-states except polling mode > ondemand: disable all P-states except max perf > msr_ia32_energy_perf_bias: 0 of 15 > > performance (care primarily about performance) > scheduler: default (optimized for performance) > cpuidle: enable all C-states subject to QOS > ondemand: all P-states, using no bias > msr_ia32_energy_perf_bias: 3 of 15 > > balanced (default) > scheduler: enable sched_mc_power_savings > cpuidle: enable all C-states subject to QOS > ondemand: all P-states, powersave_bias=5 > msr_ia32_energy_perf_bias: 7 of 15 > > powersave (can sacrifice measurable performance) > scheduler: enable sched_smt_power_savings > cpuidle: enable all C-states, subject to QOS > ondemand: disable turbo mode, powersave_bias=10 > msr_ia32_energy_perf_bias: 11 of 15 > > max_powersave (can sacrifice significant performance) > scheduler: enable sched_smt_power_savings > cpuidle: enable all C-states, subject to QOS > ondemand: min P-state (do not invoke T-states) > msr_ia32_energy_perf_bias: 15 of 15 > > Note that today Linux is typically operating in the mode > called "performance" above, rather than "balanced", > which is proposed to be the default. While a system > should work well if left in "balanced" mode, it is likely > that some users would want to use "powersave" when on > battery and perhaps shift to "performance" on A/C. > > Please let me know what you think. > > thanks, > Len Brown, Intel Open Source Technology Center > _______________________________________________ > linux-pm mailing list > linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx > https://lists.linux-foundation.org/mailman/listinfo/linux-pm _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
