On 10/07/2015 06:26 PM, Doug Smythies wrote: > On 2015.10.07 15:06 Rafael J. Wysocki wrote: >> On Wednesday, October 07, 2015 05:31:25 PM Prarit Bhargava wrote: >>> On 10/07/2015 02:52 PM, Doug Smythies wrote: >>>> On 2015.10.07 08:46 Prarit Bhargava wrote: >>>>> On 10/07/2015 11:40 AM, Doug Smythies wrote: >>>>>> >>>>>> Do we agree or disagree that the root issue seems to be (from your >>>>>> test)?: >>>>>> >>>>>> \# echo 100 > /sys/devices/system/cpu/intel_pstate/min_perf_pct >>>>>> >>>>>> [ 21.483436] store_min_perf_pct[453] min_sysfs_pct = 100 >>>>>> [ 21.489373] store_min_perf_pct[456] min_perf_pct = 100 >>>>>> [ 21.495203] store_min_perf_pct[459] min_perf_pct = 100 >>>>>> [ 21.501050] store_min_perf_pct[462] min_perf_pct = 100 >>>>> >>>>> Yep, and it appears to be done by default in Fedora & RHEL :/ ... the >>>>> issue is >>>>> still the same IMO that min_sysfs_pct & max_sysfs_pct are not cleared on a >>>>> governor switch. >>>> >>>> Clearing them will break some other things. For example, and as >>>> shown in my original reply, resume from suspend. >>>> >>>> Why? Because, at least on my computer, the governor is changed to >>>> "performance" during suspend, and the "powersave" governor is >>>> restored sometime during resume. The users wants the settings they had >>>> before the suspend. >>>> >>> Looking at this in more detail after having tested on a Intel(R) Core(TM) >>> i7-2600 CPU @ 3.40GHz in Fedora and RHEL. >>> >>> I have a feeling that the switch you're seeing (poweersave->performance, >>> suspend >>> ... resume, performance->powersave) is occurring in userspace, and not as a >>> result of the kernel. > Agreed. It is pm-suspend doing it. > >>> IMO if userspace changes the governor, all bets are off >>> on maintaining max_sysfs_pct and min_sysfs_pct. >>> >>> Here's something I cannot figure out (because I do not have an Ubuntu >>> install). >>> *Why* is Ubuntu making the governor switch during suspend/resume? Is it >>> because of archaic brokeness they were trying to paper over? > >>> That's not limited to Ubuntu, pm-utils has been doing that forever. > > Agreed. This in pm-utils, and not limited to Ubuntu. > We can ignore this issue if everyone wants, but I can envision bug reports. > >> I have no idea why has it been doing that, though. I guess the reason >> was to "speed up" PM transitions (in case it started when you were in a >> low-frequency P-state and then there was no time to bump it up before >> things got too far). > > I have no idea either, but the stated theory seems sound.
Doug, can you also apply (sorry for the cut-and-paste) diff --git a/pm/sleep.d/94cpufreq b/pm/sleep.d/94cpufreq index 6807681..2c83e8e 100755 --- a/pm/sleep.d/94cpufreq +++ b/pm/sleep.d/94cpufreq @@ -16,6 +16,8 @@ hibernate_cpufreq() gov="$x/cpufreq/scaling_governor" # if we do not have a scaling_governor file, skip. [ -f "$gov" ] || continue + # Is the governor known to work? + [ "$gov" == "intel_pstate" ] && continue # if our temporary governor is not available, skip. grep -q "$TEMPORARY_CPUFREQ_GOVERNOR" \ "$x/cpufreq/scaling_available_governors" || continue and re-test? Thanks, P. > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/