Hyper Threading Technology: Advantages and Disadvantages

Sometimes we marvel at the enormous complexity that exists within the working area of computers, and hyper-threading introduces a new entity into this complex world. Along with learning more about the computer system industry, you may find this article useful before purchasing a processor. 

 

As we all know, a computer system operates primarily through a CPU, which is responsible for converting the user's input into output; hyper-threading is a technology used to improve the efficiency of our CPUs. This is one of the innovations that occurred during the evolution of computers running various operating systems.

 

The basic idea behind hyperthreading is to be able to process multiple threads at the same time with a single microprocessor. Previously, only one thread could be managed per processor; however, Intel's hyperthreading technology now divides a processor into two logical, virtual cores that process hyper threads concurrently. 

 

Let’s take a look at what hyperthreading technology is and how it can boost CPU performance.

 

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What is Hyper- Threading Technology?

 

Hyper-threading is a trick used by the CPU to force an operating system to recognise the existence of an additional processor or core (referred to as the logical core) that exists alongside the physical core. That is, a processor with two cores appears to the operating system to have four cores or threads; four physical cores appear to have eight cores or threads, and so on. 

 

As a result, the operating system must provide work to all physical and logical cores in a consistent manner. This work distribution occurs concurrently. When one processor is busy running a large programme, the other handles the smaller programmes.

 

The logical core can be built by inserting an extra set of registers into the CPU socket. The operating system must also be designed in such a way that it can detect hyper-threading. Another requirement is that programmes that can execute under hyper-threading technology be enabled during the manufacturing process.

 

Hyper-threading allows your PC's CPU to save time between tasks by dividing it into multiple threads. When hyper-threading technology is enabled, no processor must remain idle. This allows your PC to run faster and more smoothly.

 

Intel Corporation created hyper-threading technology. It is found in some Pentium 4 processors as well as all Intel Xeon processors. Hyper-threading technology, also known as "HT Technology," allows a processor to run two threads, or sets of instructions, at the same time. 

 

Because hyper-threading allows two streams to be executed in parallel, it is almost as if two separate processors are cooperating. While hyper-threading can improve processing performance, it requires software to support multiple processors in order to benefit from the technology. 

 

Fortunately, recent versions of both Windows and Linux support multiple processors, allowing them to take advantage of hyper-threading. A video playing in Windows Media Player, for example, should not be slowed down by a Web page loading in Internet Explorer. 

 

The two programmes can be processed as separate threads at the same time thanks to hyper-threading. Individual programmes, on the other hand, can only benefit from Intel's HT Technology if they have been designed to support multiple processors.

 

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How does Hyper Threading Technology Work?

 

Sun Microsystems patented the concept behind Hyper-Threading Technology, which is a type of simultaneous multithreading technology introduced by Intel. A processor with Hyper-Threading Technology is composed of two logical processors per core, each with its own processor architectural state. 

 

Each logical processor can be stopped, interrupted, or directed to execute a specific thread independently of the other logical processors that share the same physical core.

 

To comprehend hyper-threading, you must first comprehend how your processor operates. Your CPU is also known as your computer's control center. It is made up of two major components: the control unit and the arithmetic/logic unit (ALU). 

 

The control unit directs the entire computer system to execute instructions sent to it using electrical signals. Consider the control unit to be a police officer directing traffic. The control unit does not execute instructions; rather, it decodes them and routes them to other parts of your computer system. The arithmetic/logic unit is responsible for all arithmetic and logical operations.

 

The following steps are used by a CPU to execute instructions:

 

1. The instruction is obtained by the control unit from your computer's memory.

 

2. The control unit reads the instruction and deduces its meaning before directing the required data from memory to the arithmetic/logic unit (ALU). The instruction time, or I-time, is the sum of the first two steps.

 

3. The arithmetic or logical instruction is carried out by the ALU. The ALU performs the actual operation on the data at this point.

 

4. The result of the operation is stored in memory or in a register by the ALU. Steps 3 and 4 are known as execution time, or E-time.

 

While this may appear to be a complicated procedure, all of these actions happen in fractions of a second. The faster your CPU processes instructions, the faster your computer can finish tasks. It's worth noting that if your CPU isn't very powerful, these tasks may become bottlenecked, resulting in slowdown and lag.

 

Hyper-threading comes into play here. Hyper-threading allows each core in your CPU to perform two tasks at the same time. As a result of improving the CPU's efficiency, you get better processor performance. You can use more demanding apps or games at the same time this way.

 

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Advantages and Disadvantages of Hyper- Threading Technology 

 

Hyper-threading works by duplicating certain processor sections—those that store architectural state—but not the main execution resources. 

 

This allows a hyper-threading processor to appear to the host operating system as both the usual "physical" processor and an additional "logical" processor (HTT-unaware operating systems see two "physical" processors), allowing the operating system to schedule two threads or processes concurrently and appropriately. 

 

When the current task would not use execution resources in a processor without hyper-threading, especially when the processor is stalled, a hyper-threading equipped processor can use those execution resources to execute another scheduled task. (The processor may stall as a result of a cache miss, incorrect branch prediction, or data dependency.)

 

The technology essentially allows each core to do two things at the same time. As a result, one of the advantages of Hyper-Threading is that it improves a CPU's efficiency, or more specifically, how well it processes data and instructions. 

 

It is critical to emphasize that HT Technology does not improve the performance of a processor or its individual processor cores. It is simply a hardware-specific technology that allows multiple threads of execution to be interleaved on a single core. 

 

Some of the major advantages and disadvantages of hyper threading technology are listed below :- 

 

Advantages of Hyper Threading Technology

 

1. The technology makes the best use of each CPU core. It addresses the issue of "starvation" that is common in multi-core processors. Starvation is a condition in which a specific core remains idle and unutilized due to a lack of assigned signals, data, tasks, or instructions.

 

2. It allows the CPU to process more data in less time while also running more background data without interruption, making it ideal for multitasking.

 

3. Another benefit is that the CPU can switch resources between threads. For example, while running a video game in the foreground and several background tasks, the processor will not struggle.

 

4. Simultaneous multithreading enables the design and development of smaller chips by eliminating the need for more cores, increasing the potential number of transistors within a given area, and optimizing or overclocking processing frequencies.

 

Disadvantages of Hyper Threading Technology

 

1. Technically, the technology does not double the performance of a core or the entire CPU. Instead, it simply maximizes the efficiency of each core, allowing the core and the processor as a whole to reach their full performance potential.

 

2. Some software does not support multithreading at the same time. Under processor-intensive conditions, applications that do not support HT will not run smoothly. To take advantage of the technology, software implementation is required.

 

3. Another disadvantage of Hyper-Threading is that it causes the CPU to generate more heat. To avoid hardware performance degradation and overheating, a proper cooling system must be implemented.

 

4. Performance enhancements are primarily application-dependent. Furthermore, while Hyper-Threading can be disabled via the BIOS, the user cannot activate or deactivate it at any time. This feature, like Turbo Boost, is activated by the CPU under certain conditions.

 

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Will Hyperthreading Boost The Performance? 

 

For a single socket system, hyper-threading can boost system performance by up to 30%. For dual socket systems, hyper-threading can boost performance by up to 15%. For quad-socket (or higher) systems, performance testing with and without hyper-threading enabled is recommended.

 

The diagram below shows an example of how Intel HT Technology can improve processing performance. Each Intel Xeon 64-bit processor has four execution units per core. When Intel HT Technology is disabled, the core can only execute instructions from Thread 1 or Thread 2. 

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Diagrammatic Explanation of how Intel Improves Performance

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Some execution units are idle during many clock cycles, as expected. When Hyper-Threading is enabled, the execution units can process instructions from Thread 1 and Thread 2 at the same time. In this case, hyper-threading reduces the number of clock cycles required from 10 to 7.

 

Modern operating systems and hypervisors, thankfully, are hyper-threading aware and will distribute active threads evenly across physical cores. As a result, the initial issues with performance tuning multi-core systems with hyper-threading enabled have mostly been resolved. 

 

If your environment requires CPU affinity, please consult the documentation for your operating system or hypervisor. The VMware Performance Best Practices for VMware vSphere 5.5, for /example, state

 

Hyper-threading is not always beneficial to system performance. Enabling hyper-threading may reduce system performance in extreme cases. The following is a list of environments where hyper-threading may yield little or no improvement. 

 

If your environment contains systems that meet these criteria, it is recommended that you test system performance with and without hyper-threading enabled. In general, hyper-threading is beneficial. As part of their best practice guidelines, many manufacturers recommend enabling hyper-threading. 

 

In fact, many administrators have used hyper-threading without incident for many years. However, as previously demonstrated, hyper-threading is a "your mileage may vary" technology.

 

Since its initial release in 2002, hyper-threading has come a long way. Much of the improvement can be attributed to better hyper-threading support in operating systems and hypervisors. If you were burned by hyper-threading in its early days, you might just want to give it another shot.