saving power using powertop

dw · 2008-01-29 06:55:25

hi everyone.

since i am quite disappointed with the performance of notebook's akku i decided to have a look at intels powertop utility and identify those processes that might cause the bad performance of my akku (only 1,5 hour). to start with, i run a fairly minimalistic system: pure openbox, mpd, i have installed cpufrequtils which works fine (my two processors are running at the lowest speed frequence possible almost all the time), some urxvt panels are running as well as conky, ivman, dbus, hal, openntpd, cups and slim.

anyway, when i started powertop i realized that my power usage is > 25 watts which is incredible high and i get more than 5000 wake-ups per second (> 50000 per 10 seconds). i too, realized that my notebook is > 95% of the time in state c3 which i think is good.

however, more than 85% of the wake up calls are coming from <kernel IPI> : Rescheduling interrupts. i found a "fix" which stated on should do a

echo 1 > /sys/devices/system/cpu/sched_mc_power_savings

which however didn't work.

another strange thing is that more than 10% of the wake-ups are according to acpi and again, I have no clue why this happened since i made my tests on an apart from the running daemons and openbox idle system.

anyone who has a few hints what could be wrong with my setup?

tad · 2008-01-29 21:24:37

You could possibly have CFG_IRQBALANCE enabled in your kernel.

I would suggest kernel26zen-git, it's on AUR and has all of the powertop patches and kernel cfg settings you need. Just edit the PKGBUILD and switch it to the "master" branch.

Also, this site has some up-to-date suggestions for you to try.

uastasi · 2008-03-01 13:16:48

dw wrote:

to start with, i run a fairly minimalistic system: pure openbox, mpd,

Take a look here and read about this mpd issue. It's weird how a lightweight process could determine so many wakeups.

tad wrote:

I would suggest kernel26zen-git, it's on AUR and has all of the powertop patches and kernel cfg settings you need. Just edit the PKGBUILD and switch it to the "master" branch.

Are you sure kernel26zen-git has these patches? I read carefully the PKGBUILD but there's no mention of them.

brebs · 2008-03-01 13:48:28

Also see Ubuntu wiki. This helped a lot with my ICH4 laptop, in grub:

hpet=force

uastasi · 2008-03-01 14:42:34

brebs wrote:

Also see Ubuntu wiki. This helped a lot with my ICH4 laptop, in grub:
hpet=force

As I read from here (nice guide, check it out) this feature is available by default in 2.6.24-rc2 or above. Infact this is my output with a 2.6.24-ARCH kernel:

$ grep hpet /proc/timer_list 
Clock Event Device: hpet
 set_next_event: hpet_legacy_next_event
 set_mode:       hpet_legacy_set_mode

brebs · 2008-03-01 14:55:28

uastasi wrote:

by default

Not always. Wouldn't need an option to force it on, otherwise

Funnily enough, on my Asus P5K desktop (ICH9), I need hpet=force also, to get any result from:

dmesg | grep -i hpet

This is with vanilla kernel 2.6.24.3

Arch Linux

#1 2008-01-29 06:55:25

saving power using powertop

#2 2008-01-29 21:24:37

Re: saving power using powertop

#3 2008-03-01 13:16:48

Re: saving power using powertop

#4 2008-03-01 13:48:28

Re: saving power using powertop

#5 2008-03-01 14:42:34

Re: saving power using powertop

#6 2008-03-01 14:55:28

Re: saving power using powertop

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