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. MSI X99S SLI PLUS On Linux
  2. NVIDIA GeForce GTX 970 Offers Great Linux Performance
  3. CompuLab Intense-PC2: An Excellent, Fanless, Mini PC Powered By Intel's i7 Haswell
  4. From The Atom 330 To Haswell ULT: Intel Linux Performance Benchmarks
Latest Linux Articles
  1. RunAbove: A POWER8 Compute Cloud With Offerings Up To 176 Threads
  2. 6-Way Ubuntu 14.10 Linux Desktop Benchmarks
  3. Ubuntu 14.10 XMir System Compositor Benchmarks
  4. Btrfs RAID HDD Testing On Ubuntu Linux 14.10
Latest Linux News
  1. openSUSE Factory & Tumbleweed Are Merging
  2. More Fedora Delays: Fedora 21 Beta Slips
  3. Mono Brings C# To The Unreal Engine 4
  4. Coreboot Now Has Support For Intel Broadwell Hardware
  5. Enlightenment's EFL 1.12 Alpha Has Evas GL-DRM Engine, OpenGL ES 1.1 Support
  6. GTK+ Lands Experimental Backend For Mir Display Server
  7. Ubuntu 14.10 Officially Released
  8. Mesa 10.4 Might Re-Enable HyperZ For R600g/RadeonSI
  9. Intel GVT-g GPU Virtualization Moves Closer
  10. GTK+ 3.16 To Bring Several New Features
Latest Forum Discussions
  1. Updated and Optimized Ubuntu Free Graphics Drivers
  2. Ubuntu 16.04 Might Be The Distribution's Last 32-Bit Release
  3. Linux hacker compares Solaris kernel code:
  4. HOPE: The Ease Of Python With The Speed Of C++
  5. Advertisements On Phoronix
  6. Users/Developers Threatening Fork Of Debian GNU/Linux
  7. AMD Releases UVD Video Decode Support For R600 GPUs
  8. Proof that strlcpy is un-needed