Activating the Hyper-Threading
By Gabriel Torres on October 12, 2004


With the release of several Pentium 4 processor featuring the Hyper-Threading technology there remains one question: how can one activate that technology after all?

The Hyper-Threading technology makes the operating system "believe" there are two processors installed in the machine, that is, "believe" that your machine is a Dual-Pentium 4. That is possible because there are parts of the processor that are usually idle and what Intel has done was "to free" such parts for use as if they were a new processor.

First, your CPU must support this technology. It is availabe in all Pentium 4 processors above 3 GHz or in processors below 3 GHz but with the "C" letter on it (2.4 GHz "C", 2.6 GHz "C" and 2.8 GHz "C"). Pay attention because there are processors from these speed grades that don't have the Hyper-Threading tecnology.

To make advantage of that technology, the operating system has to recognize more than one processor and has to know how to distribute tasks between them. Besides, it has to be optimized for that technology. Windows 9x/ME doesn't have that capability, and, therefore, doesn't take advantage of that technology. Windows 2000 and Windows NT recognize more than one processor, but they are not optimized for the Hyper-Threading. Thus, there are only two operating systems left to be used: Windows XP and Linux (with the Kernel from the 2.4.x version or superior).

Besides, the motherboard of the computer has to have the capacity to enable the Hyper-Threading thechnology. Only the latest Pentium 4 motherboards have such capacity. In order to work, that technology has to be enabled in the setup of the motherboard.

Having met such requirements, the Hyper-Threading will be automatically enabled. At the Windows XP, you can check if the system is using that technology in two ways. The first is through the Device Manager (icon System in the Control panel, Hardware tab). In Processors there will be two equal processors being listed (see Figure 1).

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Figure 1: Checking if Hyper-Threading is enabled.

 The second way is using the Task Manager, which is activated when we press the Control, Alt and Del keys simultaneously. At the tab Performance of that manager there is a graph called CPU Usage History. In systems with only one processor or in which the Hyper-Threading technology is disabled, there will be just one graph showing the use of the processor of the machine. In systems with two processors or in which the Hyper-Threading technology is activated, there will be two graphs showing the use rate of the processors. In the case of a machine with a Hyper-Threading processor, the second processor is virtual.

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Figure 2: Machine with a regular CPU.

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Figure 3: Machine with Hyper-Threading enabled.

Originally at http://www.hardwaresecrets.com/article/Activating-the-Hyper-Threading/20


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