Nailing the Cause of Recent Linux Power Issues

An anonymous reader writes "For the Linux kernel power regressions that were found a few months ago, and hit in Ubuntu 11.04, Phoronix has found the regression that's still present in the Linux 3.0 kernel. The power regression is caused by a change in ASPM, the Active-State Power Management, for PCI Express support."

Summary: not a Linux problem, but a BIOS problem

[ArsenneLupin]

To sum up the article in 3 sentences:

It's due to some buggy BIOSes not properly advertising power-saving features of PCIE cards. Older kernels didn't honor those BIOS hints, and disabled power to unused PCIE cards anyways (causing hangs in rare cases), whereas new kernels do the right thing (causing power wastage in lots of cases). The workaround is to specify pcie_aspm=force on the boot (Grub) command line, to tell the kernel to forge ahead, and just use power management on these cards regardless of the BIOS advice.

Re:No more Moronix, please!

[qinjuehang]

As bad as some of the Phoronix articles can be, they have contributed a lot to the community. After all, they played a pivotal role in setting up openbenchmarking.org, and are pretty much the only source of Linux hardware reviews.

tl;dr

[OliWarner]

Add pcie_aspm=force to your boot options.

Test it by editing grub (which is a temporary edit that will be lost next boot) first and test out suspend, hibernate, etc.

If that works, edit your grub configuration files. For ubuntu users this means editing /etc/default/grub and editing the GRUB_CMDLINE_LINUX_DEFAULT variable. Then call sudo update-grub.

Re:Summary: not a Linux problem, but a BIOS proble

[daid303]

The article points out that there is also a power regression in the scheduler. Which is the next thing that the writer will look at.

Never upgrade your Linux...

[Compaqt]

Never upgrade your Linux distribution in place.

Have 2 (or more) OS partitions of about 20GB each.

Install your OS's to partition 1.

Install your upgraded version to partition 2.

Easily switch back and forth.

Oh, and keep a separate /home partition.

Re:"serious bug" my ass

[David Gerard]

You are entirely correct. See Matthew Garrett's blog [dreamwidth.org] for the icky details of EFI on Linux. He makes this hideous piece of shit work for a living.

Re:Summary: not a Linux problem, but a BIOS proble

[SuricouRaven]

Linux does thing the way they should be done according to standard. Windows does things they way they actually are done in the real world. The reason is simple: BIOS vendors noticed Windows doesn't follow the standard well, and made the reasonable assumption that the vast majority of users would run windows. Thus they deviated from the standard in order to better support it.

Re:ACPI has ALWAYS favoured Windows...

[drinkypoo]

ACPI implementors (what is an ACPI vendor? can I buy it by the pound, or is it sold by the unit?) favored Windows, because Microsoft built a tool for creating ACPI tables that intentionally craps on all other operating systems, INTENTIONALLY building an invalid table for use with non-Windows operating systems. Linux now claims to be Windows in order to get a table that works. Bill Gates proposed this "feature" personally.

The dominant platform is the one supported by fraud and deceit, which helps to ensure its continuing dominance, and the proper use of apostrophes. No wait, that was me.

Re:Summary: not a Linux problem, but a BIOS proble

[Just Some Guy]

Did you read the linked PDF at all? Here's what the rest of it said:

From: Bill Gates
Sent: Sunday, January 24, 1999 8:41 AM
To: Jeff Westorinen; Ben Fathi
Cc: Carl Stork (Exchange); Nathan Myhrvold; Eric Rudder
Subject: ACPI extensions

One thing I find myself wondering about is whether we shouldn’t try and make the “ACPI” extensions somehow Windows specific.

It seems unfortunate if we do this work and get our partners to do the work and the results is that Linux works great without having to do the work.

Maybe there is no way to avoid this problem but it does bother me.

Maybe we could define the APIs so that they work well with NT and not the others even if they are open.

Or maybe we could patent something related to this.

In summary, Bill Gates explicitly wanted to break ACPI on Linux.