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. ASRock X99 Extreme3 Is An Affordable Choice For Linux Users
  2. A Walkthrough Of The New 32 System Open-Source Linux Benchmarking Test Farm
  3. Habey MITX-6771: Mini-ITX Board With Quad-Core J1900 Bay Trail
  4. OCZ Vector 150 SSD On Linux
Latest Linux Articles
  1. 17-Way Linux Graphics Card Comparison With Civilization Beyond Earth
  2. AMD Kaveri: Open-Source Radeon Gallium3D vs. Catalyst 14.12 Omega Driver
  3. 12-Way AMD Catalyst 14.12 vs. NVIDIA 346 Series Linux GPU Comparison
  4. AMD Catalyst 14.12 Omega Driver Brings Mixed Results For Linux Users
Latest Linux News
  1. Features Of The Linux 3.19 Kernel: Graphics & Disks Rule
  2. Orange Pi Is The Latest Raspberry Pi Inspired ARM Board
  3. An Open-Source Hardware Ambient Light Sensor Is Brought Up
  4. Heterogeneous Memory Management Is Coming Along For The Linux Kernel
  5. NTP Is The Latest Project Struck By Security Issues
  6. LDC 0.15.1 Released For A D Compiler In LLVM
  7. Fedora Doesn't Yet Enable F2FS File-System Support
  8. XZ 5.2 Adds New Multi-Threaded Options
  9. Intel 2.99.917 X.Org Driver Released, 3.0 Release Finally Near
  10. Server-Side XCB Is Being Discussed For The X.Org Server
Latest Forum Discussions
  1. No OpenCL with latest driver updates on Ubuntu?
  2. Looking for an nVidia GPU, but not sure how well they are supported.
  3. Need some hand holding with upgrading xserver
  4. Maker3D - create your 3D RPG
  5. FPS capped on Linux (AMD fglrx drivers)
  6. Speeding up systemd networking service
  7. Major Performance Breakthrough Discovered For Intel's Mesa Driver
  8. Are there an app using HSA ?