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 Benchmarking Platform
Phoromatic Test Orchestration

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 Articles & Reviews
  1. Sub-$20 802.11n USB WiFi Adapter That's Linux Friendly
  2. The Lenovo T450s Is Working Beautifully With Linux
  3. Linux 4.0 SSD EXT4 / Btrfs / XFS / F2FS Benchmarks
  4. Linux 4.0 Hard Drive Comparison With Six File-Systems
  5. Lenovo ThinkPad T450s Broadwell Preview
  6. How Open-Source Allowed Valve To Implement VULKAN Much Faster On The Source 2 Engine
Latest Linux News
  1. GCC 5.1 RC2 Arrives, GCC 5.1 Planned For Next Week
  2. F2FS For Linux 4.1 Has New Features & Fixes
  3. Phoronix Server Upgrade This Weekend: Dual Haswell Xeons, 96GB DDR4
  4. Google's Experimental QUIC Transport Protocol Is Showing Promise
  5. Red Hat Joins Khronos, The Group Behind OpenGL & Vulkan
  6. NetworkManager Drops WiMAX Support
  7. Wine 1.7.41 Works More On Kernel Job Objects, MSI Patches
  8. Linux 4.1 Has Improvements For The Multi-Queue Block Layer
  9. X.Org Looks To Have Six Summer Projects
  10. DragonFlyBSD Pulls In GCC 5 Compiler
Most Viewed News This Week
  1. Nouveau: NVIDIA's New Hardware Is "VERY Open-Source Unfriendly"
  2. Linux 4.0 Kernel Released
  3. Microsoft Announces An LLVM-Based Compiler For .NET
  4. Linux 4.1 Brings Many Potentially Risky x86/ASM Changes
  5. Encryption Support For EXT4
  6. VirtualBox 5.0 Beta 2 Released
  7. Mozilla Start Drafting Plans To Deprecate Insecure HTTP
  8. Elementary OS 0.3 "Freya" Now Available