Arch Linux

martin77

Member

Registered: 2010-03-14

Posts: 111

CONFIG_PCIEASPM kernel flag

Hi,

Today I got aware of Powertop, this nice app that tries to find out which of the running apps are consuming more energy.
The program launchs ok and shows this hint:

Suggestion: Enable the CONFIG_PCIEASPM kernel configuration option.
PCI Link Powermanagement (ASPM) allows the hardware to go to low power mode
automatically when a PCI-E device is idle.

My question is how can I set that flag in my running system -may be via sysctl?- or if I need to recompile the kernel instead, something I really don't want to do since I try to stick to stock -ARCH kernel.

Thanks!

Last edited by martin77 (2010-08-16 22:04:55)

ammon

Member

Registered: 2008-12-11

Posts: 413

Re: CONFIG_PCIEASPM kernel flag

Yeah you need to recompile it.
Look, that option does give some 5-10% extra battery time. But it WILL make your kernel panic.
It is still labeled experimental in kernel config, maybe sometime soon it will be usefull.

martin77

Member

Registered: 2010-03-14

Posts: 111

Re: CONFIG_PCIEASPM kernel flag

So there was why our worshiped devs haven't activated it yet
Tyvm ammon!

Last edited by martin77 (2010-08-16 23:59:49)

ammon

Member

Registered: 2008-12-11

Posts: 413

Re: CONFIG_PCIEASPM kernel flag

I just had that same kernel panic.

kernel: WARNING! power/level is deprecated; use power/control instead

I thought this was becouse that kernel config option, but I guess not. This is with stock .35-ARCH kernel.

So our worshiped devs did activated somethink fishy...

zephyr

Member

Registered: 2008-03-20

Posts: 103

Re: CONFIG_PCIEASPM kernel flag

I had trouble with the proprietary nvidia module with CONFIG_PCIEASPM=y on a 2.6.35 kernel.

The nvidia driver couldn't find the graphics device, so no X.