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

Samsung Introduces "LAB" Linux Frequency Governor

Linux Kernel

Published on 09 April 2013 05:58 PM EDT
Written by Michael Larabel in Linux Kernel
17 Comments

Samsung developers last week provided patches for a new cpufreq governor dubbed "LAB", or the "Legacy Application Boost", for the Linux kernel.

The Legacy Application Boost cpufreq governor uses historical cpuidle usage information for determining the number of currently active processor cores and uses that with the number of idle CPU cores for determining the next frequency dynamically.

Jonghwa Lee of Samsung in the mailing list patch, provides this example for LAB, "For instance, we can assume that it is working on quard core processor. When all 4 cores are busy then this governor throttles next frequency in maximum. For 3 cores, throttling will be loosen. The less core are busy, the more high frequency will be set. So, when only one core is in busy, then it releases maximum frequency that system allows. The name of 'Legacy Application Boost' came from the such above aspect which system has the highest performance for single threaded process."

More information on the Legacy Application Boost governor can be found within this mailing list message for a detailed summary. The described purpose of this new cpufreq governor developed by Samsung engineers comes down to:
One of the problem of ondemand is that it considers the most busy cpu only while doesn't care how many cpu is in busy state at the moment. This may results in unnecessary power consumption, and it'll be critical for the system having limited power source.

To get the best energy efficiency, LAB governor considers not only idle time but also the number of idle cpus. It primarily focuses on supplying adequate performance to users within the limited resource. It checks the number of idle cpus then controls the maximum frequency dynamically. And it also applies different frequency increasing level depends on that information. In simple terms the less the number of busy cpus, the better performance will be given. In addition, stable system's power consumption in the busy state can be achieved also with using LAB governor. This will help to manage and estimate power consumption in certain system.
This new Linux kernel cpufreq governor amounts to just less than 600 lines of new code. It's possible this new governor could be merged into the Linux 3.10 kernel. However, right now there is some objection to introducing any non-essential excess governors into the mainline Linux kernel.

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. Scythe Mugen MAX
  2. Intel Core i7 5960X Haswell-E On Linux
  3. Intel 80GB 530 Series M.2 SSD On Linux
  4. With A New Motherboard, The Core i7 5960X Haswell-E Lights Up
Latest Linux Articles
  1. RadeonSI Gallium3D vs. Catalyst At 4K UHD On Linux
  2. MSAA RadeonSI Gallium3D Performance Preview
  3. Intel Core i7 5960X CPU Core Scaling Under Linux
  4. AMD RadeonSI Gallium3D Performance For 4K Linux Gaming
Latest Linux News
  1. Digia Qt Spinoff Is Called "The Qt Company"
  2. GNOME 3.14 Makes More Progress In Running Natively On Wayland
  3. Minix 3.3 Released With Cortex-A8 ARM Support, NetBSD Userland Compatibility
  4. More Intel DRM Changes Queued For Linux 3.18, Including Old i830M Fixes
  5. New Code Starts Lining Up For X.Org Server 1.17
  6. Rust Developers Planning For The Rust 1.0 Language
  7. RPM 4.12 Brings New Switches, New Rpm2Archive Utility
  8. Nouveau For Linux 3.18 Gains DP Audio, More Re-Clocking
  9. SUSE Gets Bought Out Again
  10. Enlightenment E19 Officially Released With Its Own Wayland Compositor
Latest Forum Discussions
  1. support for first generation UVD blocks (RV6xx, RS780, RS880 and RV790)
  2. Nvidia joins the ranks of Apple and Microsoft
  3. Updated and Optimized Ubuntu Free Graphics Drivers
  4. New Group Calls For Boycotting Systemd
  5. Hd 6850
  6. nv and xorg.conf under Debian PPC
  7. X.Org Is Looking For Some Female Help
  8. FSF Issues Their Rebuttal To Apple's New iPhone, Watch & Apple Pay