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

A TTM Graphics Performance Fix To Go Into Linux 3.14

Linux Kernel

Published on 12 March 2014 10:26 AM EDT
Written by Michael Larabel in Linux Kernel
1 Comment

While it's late into the Linux 3.14 kernel development cycle, a patch that was introduced in Linux 3.13 with an aim of improving open-source graphics driver performance for TTM-based drivers is now being reverted since for some situations it instead decreased the performance.

Thomas Hellstrom of VMware wrote in the patch description on the DRI-devel mailing list, "A performance regression was introduced in TTM in linux 3.13 when we started using VM_PFNMAP for shared mappings. In theory this should've been faster due to less page book-keeping but it appears like VM_PFNMAP + x86 PAT + write-combine is a particularly cpu-hungry combination, as seen by largely increased cpu-usage on r200 GL video playback. Until we've sorted out why, revert to always use VM_MIXEDMAP."

The main bug leading to this Translation Table Maps memory management change being reverted was FreeDesktop.org Bug 75719. Since this Linux 3.13 TTM change, for an old ATI Radeon R200 GPU when using MPlayer video playback with the OpenGL renderer the CPU performance would get chewed up with high processor utilization.

Reverting the TTM change has now been sent in as the only patch of the ttm-fixes-3.14 pull request for landing it in time for Linux 3.14 for other users of the TTM-based DRM drivers that may have also run into performance issues.

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. AMD R600g/RadeonSI Performance On Linux 3.16 With Mesa 10.3-devel
  2. Intel Pentium G3258 On Linux
  3. SilverStone Precision PS10
  4. ASRock Z97 Extreme6
Latest Linux Articles
  1. Nouveau vs. Radeon vs. Intel Tests On Linux 3.16, Mesa 10.3-devel
  2. KVM Benchmarks On Ubuntu 14.10
  3. X.Org Server 1.16 Officially Released With Terrific Features
  4. Ubuntu With Linux 3.16 Smashes OS X 10.9.4 On The MacBook Air
Latest Linux News
  1. A New Video Has Us Real Excited About The New UT For Linux
  2. CoreOS Experiences Its First Stable Release
  3. GNOME 3.13.4 Continues Working On Wayland & More
  4. Wine 1.7.23 Has Initial Support For 64-bit Android Builds
  5. FreeBSD Developing A New Automounter, Other Features
  6. Guix 0.7 Can Now Install The GNU Operating System
  7. X.Org Foundation Still Works Towards Becoming An SPI Project
  8. Open-Source AMD Hawaii Support Should Now Be Working!
  9. KDE Developers Continue Working Toward Wayland Support
  10. Ubuntu 14.04.1 LTS Released
Latest Forum Discussions
  1. Updated and Optimized Ubuntu Free Graphics Drivers
  2. AMD "Hawaii" Open-Source GPU Acceleration Still Not Working Right
  3. Radeon related kernel bug??
  4. how the US intellegentia operates:
  5. AMD Publishes Open-Source Linux HSA Kernel Driver
  6. Next-Gen OpenGL To Be Announced Next Month
  7. Open-Source Radeon Performance Boosted By Linux 3.16
  8. Remote gui not accessible in Phoronix Test Suite 5.2