[ltp] pcie_aspm=force - module/pcie_aspm/parameters/policy = powersave any effects?

[Martin Steigerwald]

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Am Dienstag, 28. Juni 2011 schrieb Martin Steigerwald:
> Hallo!

Hallo Martin!

> After making a lot of fuss out of it, Michael Larabel finally disclosed
> results on finding the cause for the main power regression he claimed
> to have found:
>=20
> The Leading Cause Of The Recent Linux Kernel Power Problems
> http://www.phoronix.com/scan.php?page=3Darticle&item=3Dlinux_2638_aspm&nu=
m=3D
> 2
>
> I added pcie_aspm=3Dforce to kernel parameters and
>=20
> module/pcie_aspm/parameters/policy =3D powersave
>=20
> to sysfs.conf.

Shining Arcanine posted on Phoronix:

> I have a Lenovo Thinkpad T520 and I have the same situation. I think I=20
> will call Lenovo about this.
>=20
> By the way, power consumption dropped from about 26 watts to 15 watts,=20
> which is about a 40% difference. Estimates on battery life increased from=
=20
> 5 hours to 8 hours, which is in-line with the battery life figures that I=
=20
> have seen on review sites. This is a new Sandy Bridge Optimus notebook=20
> that I purchased last month, so I was affected by the regression on day=20
> 1.=20

http://phoronix.com/forums/showthread.php?56460-The-Leading-Cause-Of-The-
Recent-Linux-Kernel-Power-
Problems&s=3Da3eb3ef4763122ad96a18966d2405ea7&p=3D216154#post216154

If that figures are true this would be impressive!

Kernel messages are a bit misleading:

merkaba:~> dmesg|grep -i aspm
[    0.000000] Command line: BOOT_IMAGE=3D/vmlinuz-3.0.0-rc4-amd64=20
root=3D/dev/mapper/merkaba-debian ro pcie_aspm=3Dforce
[    0.000000] Kernel command line: BOOT_IMAGE=3D/vmlinuz-3.0.0-rc4-amd64=20
root=3D/dev/mapper/merkaba-debian ro pcie_aspm=3Dforce
[    0.000000] PCIe ASPM is forcedly enabled
[    0.496945] ACPI FADT declares the system doesn't support PCIe ASPM, so=
=20
disable it
[    0.619584] ACPI _OSC control for PCIe not granted, disabling ASPM

=46rom what I understood this should still mean that ASPM is enabled, cause=
=20
the disabling functions are NOOPs with pcie_aspm=3Dforce. But I only read=20
this from the comments. I didn=B4t verify it from the source.

Ciao,
=2D-=20
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
GPG: 03B0 0D6C 0040 0710 4AFA  B82F 991B EAAC A599 84C7

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