Power Consumption: hdparm

TwinReverb · 10-07-2009, 12:25 AM

All,

Just to drop a line to all you who want better battery life out of your laptop, here's some stuff I've done to get that. Mainly it's hdparm but here are the things I've done:

1) Recompile kernel with usbcore as <M> and add auto_suspend capability to it, with tickless enabled, with ondemand as the default CPUFreq governor, and specifying my CPU with disabling Generic X86. Tickless might only give you 1%, but that's better than nothing.

2) Using hdparm and /etc/acpi/acpi_handler.sh, tell machine to set hard drive to max power savings when on battery but max performance when plugged in. This goes in acpi_handler.sh (make sure it's executable):

Code:

if on_ac_power; then
   hdparm -B 254 /dev/sda
else
   hdparm -B 1 /dev/sda
fi

3) Set Xfce's power manager to set CPUFreq to max power savings when on battery but max performance when plugged in. I do this mainly because ondemand can do lots of switching which requires that something stop and change frequencies. In my use, this saves more power, but YMMV. Anyways, if you want to do this in acpi_handler.sh you could do this (my computer is a core 2 duo):

Code:

if on_ac_power; then
   hdparm -B 254 /dev/sda
   echo "performance" > \
      /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
   echo "performance" > \
      /sys/devices/system/cpu/cpu1/cpufreq/scaling_governor
else
   hdparm -B 1 /dev/sda
   echo "powersave" > \
      /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
   echo "powersave" > \
      /sys/devices/system/cpu/cpu1/cpufreq/scaling_governor
fi

This is just an informative post for those of us laptop-heads out there. Enjoy!

BrZ · 10-07-2009, 05:03 PM

My friend, I don't want to be a piss, but can you verify if 'Default CPUFreq governor' don't need to be 'userspace'? The policy governors (ondemand, performance...) should be modules, ok I understand that... Can you scale frequency with fixed CPUFreq? Can you test it, please?

TwinReverb · 10-07-2009, 08:00 PM

Quote:

Originally Posted by BrZ

My friend, I don't want to be a piss, but can you verify if 'Default CPUFreq governor' don't need to be 'userspace'? The policy governors (ondemand, performance...) should be modules, ok I understand that... Can you scale frequency with fixed CPUFreq? Can you test it, please?

It does not need to be userspace, but you can use userspace if you want. For me, I am saying that I set it to highest ("performance") when plugged in and lowest ("powersave") when not, but it's up to the user, as there is also:

1) Conservative: slowly changes frequency based on load
2) Ondemand: the "default", scales based on load
3) Userspace: you can set it at whatever frequency you want it to be at

Cheers!

BrZ · 10-07-2009, 08:26 PM

Thanks. I will go on another kernel rebuild on this notebook and really trying to extend battery life.
Kernel 2.3.31.2 fixed ath5k wakeup after resume/suspend and 2.3.31.3 was released today. I hope my hardware can work without major 'bugs' to forget about kernels very soon... Thanks again.