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

Nouveau Still Working On Power Management

Nouveau

Published on 25 September 2013 10:22 PM EDT
Written by Michael Larabel in Nouveau
3 Comments

Martin Peres gave a status update this week during the XDC2013 X.Org conference on the status of the project but in more particular its big troublesome spot right now: power-management / re-clocking.

Sadly there was no surprise announcement concerning the support moving along greatly, but rather a status overview of the different systems they have discovered on NVIDIA's graphics hardware for dealing with power management, performance monitoring, etc.

Power management has been a real pain for the reverse-engineering Nouveau camp since its partially software based, is almost entirely non-documented, and poorly studied/implemented in open-source, all because most vendors consider this to be a proprietary secret. Their optimal dynamic voltage / frequency scaling method they are going after is find performance bottlenecks using performance counters, lowering the clock on all other clock domains, lower the voltage on the other power domains based upon the clocks, increase the clock of the bottleneck clock domain, and then trying to do all of this quick enough and effective enough make a meaningful difference on power consumption without sacrificing performance.

Among the NVIDIA hardware counters that the project has exposed so far include PCOUNTER as blocks on monitor GPUs that monitor hardware events and tied to a given clock domain, MP counters that are per-channel/process counters in PGRAPH, PDAEMON as a set of four global counters with around 150 different signals that have been reverse-engineered so far. For PDAEMON there's five known signals and the MP counter GPGPU signals are believed to have been all reverse-engineered. Some of the Nouveau performance counters were only discovered this summer through the latest summer of code.

Nouveau open-source developers have also started understanding NVIDIA's PTHERM for thermal management, which is used for sending IRQs to the host when reaching temperature thresholds and can allow for certain events to happen (cutting GPU power, forcing the fan speed, etc). PDAEMON is what provides NVIDIA with its method of fan management, hardware scheduling, power gating, and performance/system monitoring and is found on all Fermi class GPUs and newer. Besides having its own performance counters, PDAEMON is also able to access all registers on the graphics card.

While these different hardware blocks have been discovered for NVIDIA power management, still to be implemented in the driver is stable re-clocking, dynamic voltage/frequency scaling algorithms, documenting the power/clock-gating details, and reverse-engineering more performance counter signals. This has been a big headache for Nouveau developers and end-users alike, but hopefully NVIDIA will begin to help out.

More details on this work can be found from the PDF slides and the video recording that's embedded below.


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 Launches The Core i7 5960X, Mighty Powerful Haswell-E CPUs
  2. AMD Radeon R9 290: Gallium3D vs. Catalyst Drivers
  3. AMD Radeon R9 290 Open-Source Driver Works, But Has A Ways To Go
  4. Trying The Configurable 45 Watt TDP With AMD's A10-7800 / A6-7400K
Latest Linux Articles
  1. How Intel Graphics On Linux Compare To Open-Source AMD/NVIDIA Drivers
  2. The Fastest NVIDIA GPUs For Open-Source Nouveau With Steam Linux Gaming
  3. Testing For The Latest Linux Kernel Power Regression
  4. The Most Energy Efficient Radeon GPU For AMD Linux Gaming
Latest Linux News
  1. AMD, Wine & Valve Dominated August For Linux Users
  2. Linux 3.17-rc3 Kernel Released Back On Schedule
  3. Lennart Poettering Talks Up His New Linux Vision That Involves Btrfs
  4. Mesa 10.3 RC2 Arrives Via Its New Release Manager
  5. Ubuntu 14.10's Lack Of X.Org Server 1.16 Gets Blamed On AMD
  6. MSI Motherboard BIOS Updating Remains A Pain For Linux Users
  7. See How Your Linux System Performs Against The Latest Intel/AMD CPUs
  8. AMD Steppe Eagle Flys To Coreboot
  9. Intel Beignet Is Working Out Surprisingly Well For OpenCL On Linux
  10. Coreboot Adds Lenovo X220 With Native Sandy Bridge Support
Latest Forum Discussions
  1. SSD seems slow
  2. AMD Releases UVD Video Decode Support For R600 GPUs
  3. Is laptop with Intel CPU and AMD dGPU worth buying considering especially AMD Enduro?
  4. Btrfs Gets Talked Up, Googler Encourages You To Try Btrfs
  5. Radeon HD5670 and Ubuntu 14.04
  6. Updated graphics drivers for Ubuntu 12.04 Precise LTS
  7. Catalyst 14.201.1008
  8. It's Now Possible To Play Netflix Natively On Linux Without Wine Plug-Ins