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

Intel, Radeon DRM Get Precise VBlank Timestamps

X.Org

Published on 25 October 2010 01:52 PM EDT
Written by Michael Larabel in X.Org
8 Comments

Mario Kleiner has published patches over the weekend that introduce precise vblank time-stamping support within the Linux kernel's DRM core and has implemented this support already within the Radeon and Intel kernel drivers too. The precise vblank timestamps and counting is needed by the DRI2 sync and swap extensions and in particular to conform with the OML_sync_control extension.

The existing infrastructure within the kernel DRM to generate timestamps was not reliable due to interrupt handling delays and thus were not conformant since they were not actually synchronized to a vblank. The DRM core patch adds support for vblank timestamp caching, calculating the precise vblank timestamps, and filtering of redundant vblank IRQs and removing of some race-conditions in the vblank IRQ disable/enable code path. This work was previously discussed at XDS Toulouse so it really shouldn't have a problem being accepted and hopefully is in a state where it can be pushed into the mainline Linux kernel this week prior to the Linux 2.6.37 kernel merge window closing prior to next Sunday.

For those not familiar with GLX_OML_sync_control, it's a nine year old extension that is described by the registry specification as: "This extension provides the control necessary to ensure synchronization between events on the graphics card (such as vertical retrace) and other parts of the system. It provides support for applications with real-time rendering requirements by providing precise synchronization between graphics and streaming video or audio." Right now this code is just hooked up for the Intel and Radeon DRM drivers, but we imagine hooking in the Nouveau driver will not be too far behind.

Mario has described this vblank timestamp endeavor in this mailing list message that he sent prior to mailing of the actual three-piece patch series, with additional comments inside that e-mail as well.

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. A Walkthrough Of The New 32 System Open-Source Linux Benchmarking Test Farm
  2. Habey MITX-6771: Mini-ITX Board With Quad-Core J1900 Bay Trail
  3. OCZ Vector 150 SSD On Linux
  4. Noctua i4 CPU Cooler: Great For Cooling High-End LGA-2011v3 CPUs
Latest Linux Articles
  1. AMD Kaveri: Open-Source Radeon Gallium3D vs. Catalyst 14.12 Omega Driver
  2. 12-Way AMD Catalyst 14.12 vs. NVIDIA 346 Series Linux GPU Comparison
  3. AMD Catalyst 14.12 Omega Driver Brings Mixed Results For Linux Users
  4. 6-Way Winter 2014 Linux Distribution Comparison
Latest Linux News
  1. Raspberry Pi's Gallium3D Driver Could Now Run Significantly Faster
  2. CMake 3.1 Brings Windows Additions, Target Compile Feature
  3. KDE Applications 14.12 Released
  4. Fedora 21 Released For POWER & AArch64 Hardware
  5. Elasticsearch & wxPython 3 Proposed For Fedora 22
  6. The New SuperTuxKart Looks Better, But Can Cause GPU/Driver Problems
  7. GTK+ On Windows Now Supports OpenGL
  8. New Ruby Benchmarks On GCC vs. LLVM Clang Compilers
  9. Multi-Stream Transport 4K Monitors To Become Better Supported On Linux
  10. New Supertuxkart Beta Lands New Graphics Engine, Uses OpenGL 3.1+
Latest Forum Discussions
  1. XLennart: A Game For Systemd Haters With Nothing Better To Do
  2. Need some hand holding with upgrading xserver
  3. Ubuntu Developers Still Thinking What To Do About Adobe Flash Support
  4. Microsoft buying Mojang
  5. Updated and Optimized Ubuntu Free Graphics Drivers
  6. Premium subscription "login" times out much faster than forum
  7. AMD Catalyst 14.12 Linux Driver Released -- Huge Update!
  8. Did Valve already get what they wanted from SteamOS? i.e. Win kernel + BigPicture DE