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

Radeon Gallium3D Hierarchical-Z Updated (R600)

AMD

Published on 08 February 2012 09:09 PM EST
Written by Michael Larabel in AMD
15 Comments

Now that the Radeon R600 tiling patches are done, Jerome Glisse has moved to updating the out-of-tree Hierarchical Z patches for the Radeon HD 2000 through 6000 series.

As illustrated in other articles, Hierarchical-Z can really boost graphics performance. Hierarchical Z (a.k.a. HiZ or also known as being part of the ATI/AMD HyperZ technology that's long been marketed) has already been implemented for the older open-source Radeon driver but hasn't been merged yet for any R600+ ASICs.

Hierarchical Z basically dumps unneeded pixels (as determined by checking them against the z-buffer, hence its name) as quickly as possible from the rendering pipeline. With less pixels to push forward, there's generally faster performance. Below are some very old ATI Technologies marketing slides concerning this feature.

Radeon Gallium3D Hierarchical-Z Updated (R600) Radeon Gallium3D Hierarchical-Z Updated (R600) Radeon Gallium3D Hierarchical-Z Updated (R600)
Radeon Gallium3D Hierarchical-Z Updated (R600) Radeon Gallium3D Hierarchical-Z Updated (R600) Radeon Gallium3D Hierarchical-Z Updated (R600)


While HyperZ / Hierarchical Z has been found within Radeon GPUs going back to the decade-old Radeon R100 series, it's open-source support hasn't been too quick to materialize. There's been HiZ support for pre-R600 (Radeon HD 2000 series), but the support for modern ATI/AMD graphics processors has been out of reach to most Linux desktop users.

The AMD Catalyst driver on Linux obviously supports Hyper Z's full capabilities, but the R600+ open-source support hasn't been mainlined. There's been R600+ Hierarchical Z patches floating in this FreeDesktop.org BugZilla bug for more than a year along with some patches in Alex Deucher's HTTP repository, but nothing that's worked its way mainline yet. Hierarchical Z support requires kernel DRM and Mesa (R600g) patches.

This afternoon updated Mesa/kernel patches arrived from Jerome Glisse in the aforelinked bug posting for open-source Hierarchical Z support on the GPUs from the Radeon HD 2000 series through the Radeon HD 6900 series. These patches were re-based to work atop the recent R600 tiling work.

The Hierarchical Z support for modern Radeon GPUs has been baking for about a year and we can only hope it's merged soon (assuming all issues are worked out) so that its performance can be more competitive with the proprietary Catalyst driver. This support would likely end up in the Linux 3.4 kernel and Mesa 8.1 releases.

What the Mesa patch specifically does is enable htile setup for R600g, which does a bit more than just HiZ. According to the patch description, "htile is used for HiZ and HiS support and fast Z/S clears. This commit just adds the htile setup. Fast Z/S clear is enabled. But we don't take full advantage of HiS with that patch." The kernel-side patch adds htile support to the Radeon DRM driver's command-stream (CS) checker.

The other patches found in Alex's directory for implementing the rest of the functionality in R600 Gallium3D don't appear to need any revisions at this time to work against the latest Mesa master code-base. The R600_SURF and R600_HYPERZ environment variables control the driver support.

Recent tests showed the open-source Radeon performance is about a half-decade behind Catalyst for many ATI/AMD GPUs, but the Hierarchical Z support does make the performance go up a fair amount. There's also the 2D tiling, PCI Express 2.0 support, and other not-yet-enabled-by-default features to up the frame-rates.

There will be some more Gallium3D benchmarks to publish in the near future.

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. Even With Re-Clocking, Nouveau Remains Behind NVIDIA's Proprietary Linux Driver
  2. The Power Consumption & Efficiency Of Open-Source GPU Drivers
  3. AMD R600g/RadeonSI Performance On Linux 3.16 With Mesa 10.3-devel
  4. Intel Pentium G3258 On Linux
Latest Linux Articles
  1. Nouveau vs. Radeon vs. Intel Tests On Linux 3.16, Mesa 10.3-devel
  2. KVM Benchmarks On Ubuntu 14.10
  3. X.Org Server 1.16 Officially Released With Terrific Features
  4. Ubuntu With Linux 3.16 Smashes OS X 10.9.4 On The MacBook Air
Latest Linux News
  1. The FFmpeg vs. Libav War Continues In Debian Land
  2. Grand Theft Auto Running On Direct3D Natively On Linux Shows Gallium3D Potential
  3. GCC As A Just-In Time Compiler Is An Interesting Project
  4. Age Of Wonders III Is Still Being Ported To Linux
  5. Git 2.1 To Further Mainline Windows Support Patches
  6. Debian 8.0 Jessie Is Settling For Linux 3.16
  7. Meson: A Next-Gen Build System Showing Promise
  8. Linux 3.16-rc7 Calms Things Down For The Linux 3.16 Kernel
  9. Open-Source AMD Users Report Hawaii GPU Acceleration Is Working
  10. Linus Torvalds On GCC 4.9: Pure & Utter Crap
Latest Forum Discussions
  1. List of Linux friendly Kickstarter projects
  2. Updated and Optimized Ubuntu Free Graphics Drivers
  3. Linus Torvalds On GCC 4.9: Pure & Utter Crap
  4. Porting Mesa to the Playstation 2
  5. ASRock AM1H-ITX: One Of The Best AM1 Mini-ITX Motherboards
  6. Debian + radeonsi
  7. Open-source drivers on ATI R7 260X
  8. Table test