for best results use https://github.com/01org/thermal_daemon thermal daemon along with p-state
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ACPI CPUfreq vs. Intel P-State Scaling With Linux 3.15
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Originally posted by sireangelus View Postusing the powersave governor is not enough- you need to use something like tlp to automatically force a low max cpu frequency to maximize it's effects.
Originally posted by sireangelus View PostBtw, every time i try to make a custom kernel with pstates, it crashes(as in, kernel panic so deep that i have to pull the battery) as soon as i pull the power cable- it does not like to be told what to do,apparently, so i stick with acpi.All opinions are my own not those of my employer if you know who they are.
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Are you sure? My understanding of the performance governor was that it only had two states: max freq(turbo?) and idle (not sure which idle states... S0i1?). Perhaps the problem is that it is to aggressive going to idle and the resulting transition times, for this hardware, are causing performance hits?
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Originally posted by liam View PostWould do mind attaching that wattmeter to the Nvidia board so we can get some official power numbers?Michael Larabel
https://www.michaellarabel.com/
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intel pstate
Originally posted by Michael View PostThanks. Yes I do plan to, albeit I only have one WattsUp meter and am constantly using it on many different systems so unfortunately it takes a while. I hope to have the power numbers for the Jetson TK1 out next week.
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Originally posted by Michael View PostThanks. Yes I do plan to, albeit I only have one WattsUp meter and am constantly using it on many different systems so unfortunately it takes a while. I hope to have the power numbers for the Jetson TK1 out next week.
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Colin Ian King, kernel engineer tested P state extensively with a watts meter to find out higher consumption of pstate versus acpi cpufreq and its on his recommendation pstate was disabled for Ubuntu 14.04 https://lists.ubuntu.com/archives/ke...il/041515.html
His experience reflects mine on Arch with i7 IVB laptop. I notice higher temps and more consumption, with TLP I get 4.5 hours on Ubuntu 14.04 as opposed to 3.5 hours with Arch with latest kernel 3.14 and pstate.
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Few remarks (please correct me if I get anything wrong):
P-state has only one governor (default) which can be tweaked by 3 settings (min,max,no_turbo) via sysfs.
P-state doesn't really change frequencies, everything is running at max frequencies with sleep-states inserted according to load.
So in workloads:
gaming - everything runs on max, cpu doesn't sleep unless it's forced to by high temperature
semi-idle - everything runs on max, cpu sleeps most of the time, when there are tasks to be taken care of it wakes up and goes to sleep
idle - cpu sleeps (apart from one core that is running scheduler and poriodic tick)
It came to me as a big surprise when in past posts about P-state there were 'performance' and 'powersave' governors.
<pre>
echo 100 > /sys/devices/system/cpu/intel_pstate/max_perf_pct
echo 26 > /sys/devices/system/cpu/intel_pstate/min_perf_pct
echo 0 > /sys/devices/system/cpu/intel_pstate/no_turbo
</pre>
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