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 Benchmarking Platform
Phoromatic Test Orchestration

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 News
  1. Radeon & AMDGPU DRM Fixes Queue Up For Linux 4.2
  2. KDE Applications 15.04.3 Fixes Bugs
  3. Benchmarks Of 54 Different Intel/AMD Linux Systems
  4. Linux 4.2 Bringing Support For ARCv2, HS38 CPU Cores
  5. Libdrm 2.4.62 Is An Important Update For Open-Source GPU Drivers
  6. The State of Unity 3D Game Engine, Editor On Linux
  7. ZFS On Linux 0.6.4.2 Brings Linux 4.1 Support, Fixes
  8. Old Net Burst Tests, Ubuntu Phone & Assembly x86 Were Popular Topics Last Month
  9. Qt 5.5 Officially Released
  10. Global Shortcuts In KDE Plasma Under Wayland
Latest Articles & Reviews
  1. How KDE VDG Is Trying To Make Open-Source Software Beautiful
  2. Attempting To Try Out BCache On The Linux 4.1 Kernel
  3. CompuLab's Fitlet Is A Very Tiny, Fanless, Linux PC With AMD A10 Micro
  4. AMD A10-7870K Godavari: RadeonSI Gallium3D vs. Catalyst Linux Drivers
Most Viewed News This Week
  1. Kubuntu 15.10 Could Be The End Of The Road
  2. KDBUS Won't Be Pushed Until The Linux 4.3 Kernel
  3. The State & Complications Of Porting The Unity Editor To Linux
  4. The Staging Pull For Linux 4.2: "Big, Really Big"
  5. Latest Rumor Pegs Microsoft Wanting To Buy AMD
  6. SteamOS "Brewmaster" Is Valve's New Debian 8.1 Based Version
  7. Exciting Features Merged So Far For The Linux 4.2 Kernel
  8. ARM Posts Pictures Of AMD's New Development Board