Laptop power consumption problem

[Naushika]

I recently installed 11.10 on my new Samsung NP700Z5A laptop with an Intel i7 2675QM processor and AMD Radeon GC. It's running hot and the fan keeps ramping up to full speed every minute or so which is very irritating. Powertop tells me it's consuming about 40 W when idle, while in Windows it's only around 15 W. The battery time I'm getting is consistent with those figures. I can't find any programs that would be causing load and the processor doesn't even seem to be under much load, yet something's draining power.
I've tried switching off the discrete graphics card with vgaswitcheroo but that saves only 2-3 W. I've also added acpi_osi=Linux and pcie_aspm=force in boot options with no significant change. I'm not sure if the latter even works, because:

~$ dmesg | grep -i aspm
[ 0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-3.0.0-16-generic root=UUID=df180594-b90f-4c32-a206-55afad6cb49d ro quiet splash acpi_osi=Linux pcie_aspm=force vt.handoff=7
[ 0.000000] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-3.0.0-16-generic root=UUID=df180594-b90f-4c32-a206-55afad6cb49d ro quiet splash acpi_osi=Linux pcie_aspm=force vt.handoff=7
[ 0.000000] PCIe ASPM is forcedly enabled
[ 1.214544] ACPI _OSC control for PCIe not granted, disabling ASPM

I've read some posts though that say you get the last message anyway even if aspm is enabled.

Any suggestions what I could try? The fan noise makes the machine a pain to use and the lousy battery life means I can't really take it anywhere with me. And running hot can't do it good in the long run.

[SecretCode]

Where do you see a Watts value in powertop, out of interest?

It shouldn't be that bad, definitely.

Does iotop show a lot of I/O? Sometimes I/O can be busy even when processes do not show as using much CPU.

[Naushika]

I think i've seen a post saying the latest version of powertop doesn't show watts. I'm running 1.13. It shows power consumption when you're on battery.

I don't see very much I/O happening, I don't think that's the culprit.

[SecretCode]

I have v1.97! I thought this was a fresh install of 11.10 - how come you have an old version? Are there other old packages that might be contributing to power issues?

What is your kernel version?

[Naushika]

I installed the old version of Powertop just because someone said the new one doesn't show wattage. Otherwise it's a fresh install without any customization (apart from disc partitioning of course since I have a dual boot with Windows). The kernel is 3.0.0-16.

[SteveRiley]

Perhaps some tips in my post How to enable power management features will be helpful. Since you don't have a ThinkPad, you probably should skip the parts about Thinkfan. But do take a look at the shell script.

The new version of Powertop shows wattage drain only when the computer is on battery. If you switch between AC and battery, you have to exit and restart Powertop.

[Naushika]

Sorry I didn't have time to get back to this sooner. Thanks for the tips Steve. I've got the boot parameters you've listed and I copied your script. I think it helped a little.
Installing laptop-mode-tools had a clear effect on power usage, it's now 'down' to about 30-33W when idle. Also the fan control works better now, they are on some intermediate speed most of the time instead of speeding up and slowing down all the time. Could be better still.

[GreyGeek]

Is your CPU showing that it is throttling down when idling?

The repository has cpufreqd and cpufrequtils to help controlling CPU states.

Another is indicator-cpufreq.

[SteveRiley]

Recent kernels have been using ondemand as the default. I'm no longer installing cpufrequtils now.

Interesting to learn that laptop-mode-tools worked, Naushika. I thought I read somewhere a while ago about that utility no longer being maintained, but I can't recall where.

[Naushika]

From Stefano's blog I found out that (at least in this laptop) after giving the OFF command through vgaswitcheroo, you need to do suspend before the Radeon card actually gets switched off. I was imagining things earlier when I thought I saw some effect on power usage. But after suspend it really drops to about 18 W. Yeah!

Is there any way to get the discrete graphics to power off without suspend, or to stop the card from being powered up at all at startup? Having to do suspend every time I start the computer seems a bit silly. Especially because hibernation doesn't work so I have to do proper shut down. But at least I now have decent battery life, temperatures stay under control and the fan mostly keeps quiet, so I'm happy.

The processor throttling seems to work ok, so my problem really is the graphics card. I guess the open-source driver isn't very good with power control. But I don't need the discrete graphics at the moment anyway so it's ok with me.

[SteveRiley]

Is there any way to get the discrete graphics to power off without suspend, or to stop the card from being powered up at all at startup?

Can you control this in your computer's BIOS/UEFI settings? On my T520 I've completely disabled the nVidia graphics and rely only on Intel integrated HD. By switching it off at the BIOS/UEFI level, the operating system doesn't even detect the chip.

[GreyGeek]

I know this stuff is leaking out of my brain faster than I can stuff it back in, but if one changes /etc/default/grub isn't it necessary to run update-grub?

[SteveRiley]

If one makes changes to /etc/default/grub, then yes.

But changes to the BIOS/UEFI are lower-level than GRUB, so it isn't necessary to run update-grub in this case.

[Naushika]

It looks like some recent updates solved the problem for me, and now the discrete graphics card stays switched off. Which is great because the UEFI/BIOS in this laptop is very stripped down, there's no mention of the graphics card in it. I had blacklisted the Radeon module earlier in /etc/modprobe.d/blacklist.conf in the hope that would stop the card from being powered up but that had no effect until now. Or maybe it was the update process itself that did the trick; maybe I should have given some command to get the blacklisting registered? Anyway the graphics card issue is now solved and I'm using around 20 W while doing some light surfing or writing, which is good enough.

But, when you get one thing nailed there's a new problem:
At some point I started noticing a constant clicking from my hard drive. I've read about powersave settings having harmful effects on some hard drives (described in bug #59695) so I installed smartmontools to see if I had that problem, and it seems so. The load cycle count given by smartctl increases by 5-10 counts/minute. That rate could destroy the disc in a few months. In my case, this behaviour doesn't have anything to do with the power scheme in use but it depends on whether AC was connected at boot. If it was, the drive does not cycle at all even if the plug is pulled afterwards. The drive is Hitachi HTS727575.

I mostly keep my laptop on AC, and now that I'm aware of this I can avoid booting on battery, but it would be nice to have some control over how the disc behaves because parking the heads when travelling is actually useful to protect it. Plus it could be a serious issue to someone who has the same model and mostly uses battery.

Unfortunately I noticed this just recently so don't know if this issue has been there from the beginning or if it was caused by some of the tweaks I used to reduce power usage. I haven't had time to read through the bug report so I'm not sure what I could do about it, but from the last posts it looks like updating to 12.4 might solve it. But I'm a bit reluctant to install an alpha version because I'm not that experienced and I need to get some work done on this machine.

[MoonRise]

Is your CPU showing that it is throttling down when idling?

The repository has cpufreqd and cpufrequtils to help controlling CPU states.

Another is indicator-cpufreq.

As far as these Utilities. Once set are they only good for the current session or does it set that somehwere for use on next boot?