VIA LongHaul is a
CPU speed throttling and
power saving technology developed by
VIA Technologies
VIA Technologies Inc. (), is a Taiwanese manufacturer of integrated circuits, mainly motherboard chipsets, CPUs, and memory. It was the world's largest independent manufacturer of motherboard chipsets. As a fabless semiconductor company, VIA ...
. By executing specialized
instructions
Instruction or instructions may refer to:
Computing
* Instruction, one operation of a processor within a computer architecture instruction set
* Computer program, a collection of instructions
Music
* Instruction (band), a 2002 rock band from Ne ...
,
software
Software is a set of computer programs and associated software documentation, documentation and data (computing), data. This is in contrast to Computer hardware, hardware, from which the system is built and which actually performs the work.
...
can exercise fine
control
Control may refer to:
Basic meanings Economics and business
* Control (management), an element of management
* Control, an element of management accounting
* Comptroller (or controller), a senior financial officer in an organization
* Controllin ...
on the
bus-to-core frequency ratio and
CPU core voltage The CPU core voltage (''VCORE'') is the power supply voltage supplied to the CPU (which is a digital circuit), GPU, or other device containing a processing core. The amount of power a CPU uses, and thus the amount of heat it dissipates, is the pr ...
. When the
system first
boots
A boot is a type of footwear.
Boot or Boots may also refer to:
Businesses
* Boot Inn, Chester, Cheshire, England
* Boots (company), a high-street pharmacy chain and manufacturer of pharmaceuticals in the United Kingdom
* The Boot, Cromer St ...
, the ratio and voltage are set to hardware
defaults. While the
operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
Time-sharing operating systems schedule tasks for efficient use of the system and may also i ...
runs, a ''CPU
driver'' controls the throttling according to how much
load is put on the CPU.
This fine control over the CPU's operating parameters brings LongHaul in contrast to other competing technologies, where a CPU is typically allowed to switch between only two states - one that is fast but power-consuming and one that is slow but uses
less power. However LongHaul is considered similar to
Transmeta
Transmeta Corporation was an American fabless semiconductor company based in Santa Clara, California. It developed low power x86 compatible microprocessors based on a VLIW core and a software layer called Code Morphing Software.
Code Morphing ...
's
LongRun LongRun and LongRun2 are power management technologies introduced by Transmeta. LongRun was introduced with the Crusoe processor, while LongRun2 was introduced with the Efficeon processor. LongRun2 has since been licensed to Fujitsu, NEC, Sony, ...
technology.
There are 3 versions of LongHaul:
* Version 1 only supports
dynamic frequency scaling
Dynamic frequency scaling (also known as CPU throttling) is a power management technique in computer architecture whereby the frequency of a microprocessor can be automatically adjusted "on the fly" depending on the actual needs, to conserve ...
and is implemented in the
Cyrix III
Cyrix III is an x86-compatible Socket 370 CPU. VIA Technologies launched the processor in February 2000. VIA had purchased both Centaur Technology and Cyrix. Cyrix III was to be based upon a core from one of the two companies.
History
The Cy ...
Samuel (C5A) core and
C3 Samuel 2 (C5B) stepping 0 core.
* Version 2 adds
voltage scaling
Dynamic voltage scaling is a power management technique in computer architecture, where the voltage used in a component is increased or decreased, depending upon circumstances. Dynamic voltage scaling to increase voltage is known as overvolting; d ...
and is implemented in the
C3 Samuel 2 (C5B) stepping 1-7 and Ezra (C5C) cores.
* Version 3 was renamed to PowerSaver and is implemented in the
C3 Ezra-T (C5N) and Nehemiah cores as well as the
C7 Esther (C5J) core. Some variants of the C7-D do not support PowerSaver.
Processors supporting LongHaul
*
Cyrix III
Cyrix III is an x86-compatible Socket 370 CPU. VIA Technologies launched the processor in February 2000. VIA had purchased both Centaur Technology and Cyrix. Cyrix III was to be based upon a core from one of the two companies.
History
The Cy ...
- some model
*
VIA C3
The VIA C3 is a family of x86 central processing units for personal computers designed by Centaur Technology and sold by VIA Technologies. The different CPU cores are built following the design methodology of Centaur Technology.
In addition to ...
*
VIA C7
The VIA C7 is an x86 central processing unit designed by Centaur Technology and sold by VIA Technologies.
Product history
The C7 delivers a number of improvements to the older VIA C3 cores but is nearly identical to the latest VIA C3 Nehemiah ...
(PowerSaver)
*
VIA Nano
The VIA Nano (formerly code-named VIA Isaiah) is a 64-bit CPU for personal computers. The VIA Nano was released by VIA Technologies in 2008 after five years of development by its CPU division, Centaur Technology. This new Isaiah 64-bit architec ...
(PowerSaver)
External links
VIA C3 in EBGA Datasheet- ''LongHaul'' entry
Computer hardware tuning
Clock signal
VIA Technologies
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