If I disable intel_pstate on my kernel command line, I end up with access only to the speedstep and p4-clockmod drivers, and no acpi-cpufreq driver. Is there a way to download the acpi-cpufreq driver? I've tried a couple of things without success. BTW, I haven't gotten the chance to modify the BIOS yet (waiting on a sysadmin). -Melanie On Fri, Oct 25, 2013 at 11:38 AM, Dirk Brandewie <dirk.brandewie@xxxxxxxxx> wrote: > On 10/25/2013 08:13 AM, Melanie Kambadur wrote: >> >> 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, > > > Not hardware based but specific to Intel CPUs SandyBridge+ > > >> and strictly an alternative to (i.e., it cannot be >> combined with) OS governors and drivers. > > > Correct > > >> If I want to use ondemand with my Dell server I need to: > > > Add intel_pstate=disable on your kernel commond line, this will take > intel_pstate out of the picture. For the rest of the config on the > dell system I am no help sorry. > > >> >> 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? > > > If intel_pstate is being used acpi_cpufreq will not be loaded. Setting > performance with intel_pstate should work I will look to see where the > bug is. > > >> >> Finally, the behavior of the C-states is totally independent of >> P-states and any kind of OS-based frequency tuning policy, correct? > > > 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
