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

KMS Locking Pulled Into Queue For Linux 3.9 Kernel

Intel

Published on 07 February 2013 12:58 PM EST
Written by Michael Larabel in Intel
Comment On This Article

Intel's work on kernel mode-setting locking has been pulled into the drm-next repository for merging into the Linux 3.9 kernel as one of several open-source Linux graphics driver changes for this next kernel release.

As far as what KMS locking means for users, Daniel Vetter has described it in a detailed blog post. Vetter explains, "The aim of this locking rework is that ioctls which a compositor should be might call for every frame (set_cursor, page_flip, addfb, rmfb and getfb/create_handle) should not be able to block on kms background activities like output detection. And since each EDID read takes about 25ms (in the best case), that always means we'll drop at least one frame. The solution is to add per-crtc locking for these ioctls, and restrict background activities to only use the global lock. Change-the-world type of events (modeset, dpms, ...) need to grab all locks."

However, making this locking work right isn't too easy. There's still some work ahead before there's "perfect page-flip" support for the Linux kernel. "The downside of this all is that we can now enable some really paranoid inter-frame jitter checks and vblank counter timestamp checks in the kms_flip testcase. After all, no frames should be dropped any longer. But it turns out that a lot of the different platforms still have small issues here and there with races and other inconsistencies like completing a page flip immediately right after a modeset. So there's still plenty of work to do until we have perfect pageflip support. And there's also a few funny issues like racing gpu hangs against pageflips, client crashes against pageflips or trying to flip overlays and cursor on the same vblank as the underlying framebuffer."

Other Linux 3.9 DRM graphics features are covered in Intel's Linux DRM Driver Plans For 2013, the no-reloc optimization, Haswell improvements, and several other changes.

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. Btrfs On 4 x Intel SSDs In RAID 0/1/5/6/10
  2. AMD Radeon R9 290 On Ubuntu 14.10: RadeonSI Gallium3D vs. Catalyst
  3. MSI X99S SLI PLUS On Linux
  4. NVIDIA GeForce GTX 970 Offers Great Linux Performance
Latest Linux Articles
  1. 6-Way Ubuntu 14.10 Radeon Gallium3D vs. Catalyst Driver Comparison
  2. NVIDIA vs. Nouveau Drivers On Ubuntu 14.10
  3. Ubuntu 14.10 Offers AMD Radeon Driver Performance Improvements
  4. Btrfs RAID: Linux 3.10 To Linux 3.18 Benchmarks
Latest Linux News
  1. GLAMOR Acceleration Continues To Be Cleaned Up
  2. Russia's Yandex Web Browser Finally Released For Linux
  3. Linux Kernel Finally Being Optimized For SSHDs
  4. GPU Profiling Support Lands In Mozilla Firefox
  5. Kubuntu 15.04 Will Use KDE's Plasma 5 By Default
  6. KDBUS Submitted For Review To The Mainline Linux Kernel
  7. An Intel-Based Ubuntu Touch Tablet Is Planning To Launch Soon
  8. MIAOW: An Open-Source GPU Design Based On AMD's Southern Islands
  9. X.Org Server 1.17 RC1 Released, Exciting For GLAMOR & Modesetting
  10. OpenGL 4.x Support For Mesa Still Inching Along
Latest Forum Discussions
  1. Reducing The CPU Usage In Mesa To Improve Performance
  2. Is foolish currently develop in machine code, hexadecimal and assembly?
  3. Help diagnosing problems with a Readon HD 4670 on Mesa 10.3.2-1
  4. Advertisements On Phoronix
  5. nv and xorg.conf under Debian PPC
  6. Looking for a Open-Source AMD experienced Linux mentor
  7. Bad perfomance in gaming
  8. Dead Island for Linux (?)