1. Computers
  2. Display Drivers
  3. Graphics Cards
  4. Memory
  5. Motherboards
  6. Processors
  7. Software
  8. Storage
  9. Operating Systems


Facebook RSS Twitter Twitter Google Plus


Phoronix Test Suite

OpenBenchmarking.org

PCI-E ASPM Change For The Linux 3.4 Kernel

Linux Kernel

Published on 23 March 2012 09:05 AM EDT
Written by Michael Larabel in Linux Kernel
1 Comment

The PCI pull request went in yesterday for the Linux 3.4 kernel. Overall it's a fairly uninteresting pull for the 3.4 cycle, but there's two basic exceptions.

First of all, this was the last pull request where Jesse Barnes of Intel is handling the role as maintainer of the Linux PCI sub-system. Jesse has announced he's handing off the PCI maintainer role to Bjorn Helgaas, a software engineer at Google. "He's been a core PCI and Linux contributor for some time now, and has kindly volunteered to take over. I just don't feel I have the time for PCI review and work that it deserves lately (I've taken on some other projects), and haven't been as responsive lately as I'd like, so I approached Bjorn asking if he'd like to manage things. He's going to give it a try, and I'm confident he'll do at least as well as I have in keeping the tree managed, patches flowing, and keeping things stable."

Bjorn Helgaas has been an engineer at Google for the past year while previous to that he served for more than a decade at Hewlett-Packard as a Linux kernel developer.

The PCI pull itself this time is relatively uninteresting, but there's one more PCI Express Active State Power Management (PCI-E ASPM) change from Red Hat's Matthew Garrett.

Matthew was the one that came up with the proper Linux kernel ASPM fix back in November after earlier in the year I had pointed out this very serious kernel power regression. His fix, which entered the Linux 3.3 kernel and has since been back-ported to stable branches, remains valid.

What Matthew's changing this time about this PCI Express power-savings feature is support for setting the default PCI-E ASPM default policy. Now, alternatively, distribution vendors can set this default power management policy to use regardless of what the BIOS exposes to the operating system. "Distributions may wish to provide different defaults for PCIE ASPM depending on their target audience. Provide a configuration option for choosing the default policy."

From the Linux kernel build configuration there is now a PCI-E ASPM option where one can choose to use the default BIOS PCI-E ASPM state (this remains the default), enforce the power-saving mode where PCI Express ASPM L0s and L1 are set even if the BIOS did not, or enforce the performance mode where PCI Express ASPM L0s and L1 are disabled even if the BIOS has them set to be enabled. Most Linux distributions, however, will likely stick to using the BIOS defaults policy.

The Linux 3.4 PCI pull request can be found, as usual, on the Linux kernel mailing list.

About The Author
Michael Larabel is the principal author of Phoronix.com and founded the web-site in 2004 with a focus on enriching the Linux hardware experience and being the largest web-site devoted to Linux hardware reviews, particularly for products relevant to Linux gamers and enthusiasts but also commonly reviewing servers/workstations and embedded Linux devices. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics hardware drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated testing software. He can be followed via and or contacted via .
Latest Linux Hardware Reviews
  1. Intel Xeon E5-1680 v3 & E5-2687W v3 Compared To The Core i7 5960X On Linux
  2. Intel 120GB 530 Series SSD Linux Performance
  3. Btrfs/EXT4/XFS/F2FS RAID 0/1/5/6/10 Linux Benchmarks On Four SSDs
  4. AMD's Windows Catalyst Driver Remains Largely Faster Than Linux Drivers
Latest Linux Articles
  1. NVIDIA vs. Nouveau Drivers With Linux 3.18 + Mesa 10.4-devel
  2. Is The Open-Source NVIDIA Driver Fast Enough For Steam On Linux Gaming?
  3. Linux 3.18 File-System Performance Minimally Changed But Possible Regressions
  4. AMD Radeon Gallium3D Is Catching Up & Sometimes Beating Catalyst On Linux
Latest Linux News
  1. Using NVIDIA's NVENC On Linux With FFmpeg
  2. There's Talk Again About An "Open To The Core" Ubuntu Laptop
  3. PowerVR SGX Driver Code Gets Leaked
  4. V2 Of KDBUS Published For Linux Kernel Review
  5. VirtualBox 4.3.20 Arrives, Still No Sign Of VirtualBox 4.4
  6. Scientific Linux 6.6 vs. Scientific Linux 7.0 Benchmarks
  7. Qualcomm Looks To Get Into The ARM Server Business
  8. HHVM 3.4 Adds New Features, Support
  9. More Radeon Driver Changes Queued For Linux 3.19
  10. Unigine 2.0 Alpha 2 Adds C# Support
Latest Forum Discussions
  1. Cant get working Kaveri APU - A10-7850k
  2. Script for Fan Speed Control
  3. Roadmap to Catalyst 14.10 ?
  4. Debian Init System Coupling Vote Results
  5. The Slides Announcing The New "AMDGPU" Kernel Driver
  6. Updated and Optimized Ubuntu Free Graphics Drivers
  7. Debian Developer Resigns From The Systemd Maintainership Team
  8. Ubuntu Developers Still Thinking What To Do About Adobe Flash Support