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. Intel Launches The Core i7 5960X, Mighty Powerful Haswell-E CPUs
  2. AMD Radeon R9 290: Gallium3D vs. Catalyst Drivers
  3. AMD Radeon R9 290 Open-Source Driver Works, But Has A Ways To Go
  4. Trying The Configurable 45 Watt TDP With AMD's A10-7800 / A6-7400K
Latest Linux Articles
  1. Testing For The Latest Linux Kernel Power Regression
  2. The Most Energy Efficient Radeon GPU For AMD Linux Gaming
  3. 20-Way Radeon Comparison With Open-Source Graphics For Steam On Linux Gaming
  4. Preview: OS X 10.10 Yosemite vs. Ubuntu Linux GPU Performance
Latest Linux News
  1. LibreOffice Ported To 64-bit ARM (AArch64)
  2. Enlightenment E19 RC3 Shows Off The New Wayland Compositor
  3. Metro Redux Is Going To Require OpenGL 4.x On Linux
  4. Jailhouse v0.1 Released As A Basic Hypervisor For Linux
  5. Google's Chromebook "Samus" Now Supported By Coreboot
  6. Chrome 38 Now In Beta With Exciting Advancements
  7. Ubuntu's Utopic Unicorn 14.10 Beta 1 Released
  8. Genode OS 14.08 Has New GUI Architecture, Pluggable VFS
  9. Another Intel Linux Power Regression Is Being Investigated
  10. DNF Makes It A Step Closer To Replacing Yum On Fedora
Latest Forum Discussions
  1. Users defect to Linux as OpenBSD removes Lynx from base system
  2. Updated and Optimized Ubuntu Free Graphics Drivers
  3. Canonical Joined The Khronos Group To Help Mir/Wayland Drivers
  4. Radeon HD5670 and Ubuntu 14.04
  5. AMD Releases UVD Video Decode Support For R600 GPUs
  6. Best Radeon for a Power Mac G5?
  7. OC capability - Intel Core i5 4690K & Biostar Hi-Fi Z97WE
  8. Announcing radeontop, a tool for viewing the GPU usage