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

An OpenGL Optimization Extension Merged Into Mesa

Mesa

Published on 06 October 2013 02:49 PM EDT
Written by Michael Larabel in Mesa
18 Comments

Yesterday Mesa received support for a new OpenGL extension and after that another useful OpenGL 4.2 extension was added to Mesa and implemented within the Intel OpenGL Linux driver. This latest extension can be used for a driver performance optimization.

The newest extension implemented in Mesa and more specifically the Intel DRI driver is ARB_conservative_depth. The ARB_conservative_depth extension has been implemented for Ivy Bridge "Gen7" hardware and newer. With time, the extension will be implemented by the Radeon and Nouveau Gallium3D drivers. There is also support for ARB_conservative_depth within the Softpipe driver.

OpenGL's ARB_conservative_depth extension allows games and applications to pass information to the OpenGL driver for implementing a performance optimization of an early depth test run before the fragment shader so the driver can skip the evaluation process if the fragment will be discarded due to being occluded.

The OpenGL.org registry lays out the extension in full.
There is a common optimization for hardware accelerated implementation of OpenGL which relies on an early depth test to be run before the fragment shader so that the shader evaluation can be skipped if the fragment ends up being discarded because it is occluded.

This optimization does not affect the final rendering, and is typically possible when the fragment does not change the depth programmatically. (i.e.: it does not write to the built-in gl_FragDepth output). There are, however a class of operations on the depth in the shader which could still be performed while allowing the early depth test to operate.

This extension allows the application to pass enough information to the GL implementation to activate such optimizations safely.
The ARB_conservative_depth extension is a requirement for OpenGL 4.2 compliance. This Git commit enabled the Intel i965 ARB_conservative_depth depth support for Gen7+ hardware.

Latest Linux Hardware Reviews
  1. Overclocking The AMD AM1 Athlon & Sempron APUs
  2. AMD Athlon 5350 / 5150 & Sempron 3850 / 2650
  3. Upgraded Kernel & Mesa Yield A Big Boost For Athlon R3 Graphics
  4. AMD Athlon 5350 APU On Linux
Latest Linux Articles
  1. A Quick Look At GCC 4.9 vs. LLVM Clang 3.5
  2. Are AMD Athlon/Sempron APUs Fast Enough For Steam On Linux?
  3. AMD Athlon's R3 Graphics: RadeonSI Gallium3D vs. Catalyst
  4. GCC 4.9 Compiler Optimization Benchmarks For Faster Binaries
Latest Linux News
  1. Trying Out Radeon R9 290 Graphics On Open-Source
  2. Intel Broadwell GT3 Graphics Have Dual BSD Rings
  3. Early Linux 3.15 Benchmarks Of Intel Core i7 + Radeon
  4. Red Hat Releases Its RHEL 7 Release Candidate
  5. New Features Coming To Xubuntu 14.04 LTS
  6. NVIDIA Officially Releases CUDA 6
  7. Google Releases An AutoFDO Converter For Perf In LLVM
  8. Fedora 21 To Evaluate Remote Journal Logging, 64-bit ARM Emulation
  9. Star Citizen Will Be Coming To Linux
  10. Ubuntu 14.10 Convergence To Focus On Replacing Core Apps
  11. The Results Of Optimizing Radeon's VRAM Behavior
  12. Kernel Developers Discuss Improving Kernel Configurations
Latest Forum Discussions
  1. Linux Kernel Developers Fed Up With Ridiculous Bugs In Systemd
  2. The GNOME Foundation Is Running Short On Money
  3. Bye bye BSD, Hello Linux: A Sys Admin's Story
  4. New tool for undervolt/overclock AMD K8L and K10 processors
  5. How to enable opengl 3.3 on r9 270?
  6. R290x sound problems
  7. radeon-profile: tool for changing profiles and monitoring some GPU parameters
  8. Torvalds Is Unconvinced By LTO'ing A Linux Kernel