Arch Linux

bwat47

Member

Registered: 2009-10-07

Posts: 638

laptop-mode/powertop questions

I was running powertop2 and had questions about some of the results. On the tunabled tab it gives me 3 "bad" entries:

   Bad           VM writeback timeout                                                         
   Bad           Enable Audio codec power management
   Bad           Power Aware CPU scheduler

It seems like it might be wrong about a few of these, but I'm not sure. I am pretty sure vm_writeback is fine because laptop-mode seems to increase it significantly on battery, from 500 to 60000. I enabled the audio codec and cpu power management manually in the laptop-mode config files but it still reports them as bad. When I cat them to see what they are set to I am getting "2" as a result instead of 1 or 0 which is confusing to me, as I can't find what it is supposed to mean if they return 2:

[brandon@brandon-arch ~]$ cat /sys/module/snd_hda_intel/parameters/power_save
2

[brandon@brandon-arch ~]$ cat /sys/devices/system/cpu/sched_mc_power_savings
2

[brandon@brandon-arch ~]$ cat /sys/devices/system/cpu/sched_smt_power_savings
2

^These are with the config files set to "auto" in the laptop-mode config files, if I set them to "1" I get the exact same thing.

gururise

Member

Registered: 2011-11-03

Posts: 33

Re: laptop-mode/powertop questions

I think you are correct, and powertop is not aware of the new settings available for these tunables.  I remember reading somewhere that the sched_smt_power_savings for newer kernels can be 0,1 or 2, with 2 providing the highest power settings; however, powertop seems to only be aware of the settings 0,1 and if you have it set to 2, it will report it as "BAD".