I appreciate you all taking the time to walk me through this. Let me see if I understand the new comments. Intel p-states is a HW-based power manager, and strictly an alternative to (i.e., it cannot be combined with) OS governors and drivers. If I want to use ondemand with my Dell server I need to: 1) Modify the BIOS to give the OS exclusive power management control because otherwise an OS driver won't be able to work properly. (I think I know how to do this now after some more reading, e.g. here http://en.community.dell.com/techcenter/power-cooling/w/wiki/best-practices-in-power-management.aspx if anyone is curious.) 2) Set the O/S cpufreq driver to acpi_cpufreq, and 3) Set the O/S cpufreq governor to ondemand. Is that correct? Also, which driver should I try to use if I want to test the performance & powersave governors again (or if I replicate the behavior of the performance governor by manually modifying the min_perf_pct value as Dirk suggested)? Will it still be acpi_cpufreq? Finally, the behavior of the C-states is totally independent of P-states and any kind of OS-based frequency tuning policy, correct? However, David recommends that leaving C1E on rarely hurts performance while significantly improving power. -Melanie On Fri, Oct 25, 2013 at 10:40 AM, Dirk Brandewie <dirk.brandewie@xxxxxxxxx> wrote: > On 10/24/2013 12:42 PM, Melanie Kambadur wrote: >> >> >> From /sys/devices/system/cpu/cpuN/cpufreq/scaling_driver I get that >> the current p-state driver is called "intel_pstate". David, you >> mention that the firmware governors are not very efficient, do you >> suggest replacing the intel_pstate driver with a different driver? > > > I will need to look and see why changing to performance isn't working > correctly. > > To get the behavior of the performance governor you can use > > echo 100 > /sys/devices/system/cpu/intel_pstate/min_perf_pct > > This will force intel_pstate to select the highest P state and > leave it there. > > Turbostat is useful for collecting frequency (P state) and idle (C state) > information. > > --Dirk > > -- 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
