What is the Difference Between Hyper Threading and Multithreading

The main difference between hyper threading and multithreading is that hyper threading converts a single physical processor into two virtual processors while multithreading executes multiple threads in a single process simultaneously.

Hyper threading is a technology developed by Intel to increase the performance of the CPU/processor. It allows a single CPU to run two threads. On the other hand, multithreading is a mechanism that allows running multiple lightweight threads within a process at the same time. Each thread has their own program counter, stack, registers, etc.

Key Areas Covered

1. What is Hyper Threading
     – Definition, Functionality
2. What is Multithreading
     – Definition, Functionality
3. What is the Difference Between Hyper Threading and Multithreading
     – Comparison of Key Differences

Key Terms

Hyper Threading, Multithreading

What is Hyper Threading

Hyper Threading is a technology designed to increase the performance of the CPU. It allows multiple threads to run on each core to make the CPU run efficiently. It increases the amount of work performed by the CPU within a unit time. A core is the execution unit of the CPU. Initially, there was only one core in the CPU. Later, manufacturers added more cores to the CPU to increase the number of instructions executed by the CPU at a time.

Hyper threading is a mechanism to increase the performance of the CPU further. It makes the operating system recognize each physical core as two virtual or logical cores. In other words, it virtually increases the number of cores in a CPU. Therefore, a single processor runs two threads. It is important to note that hyper threading really does not increase the number of cores – it just increases the cores virtually or logically. Each virtual core can work independently.  Furthermore, a hyper threading enabled CPU contains 2 sets of general purpose registers, control registers, and other architecture components, but they share the same cache, buses and execution units.

What is Multithreading

A process is a program in execution. Creating processes for each task is resource consuming. Therefore, it is possible to divide a single process into multiple sub-processes and assign tasks to each subprocess. Each sub-process is called a thread. We can also consider a thread as a lightweight process. Multithreading is the mechanism of dividing a process into multiple threads and allowing them to execute simultaneously. Here, each thread operates independently.

There are two types of threads as kernel thread and user thread. Kernel managed threads are kernel threads whereas the user managed threads are user threads.

There are various multithreading models.

Many to one model – Multiple user threads map to a single kernel thread

One to one model – Each kernel thread manages a single user thread

Many to many models – Multiple user threads map to similar or smaller amount of kernel threads

Difference Between Hyper Threading and Multithreading

Definition

Hyper Threading is a technology that allows a single processor to operate like two separate processors to the operating system and the application programs that use it. Multithreading is a mechanism that allows multiple threads to exist within the context of a process such that they execute independently but share their process resources. Thus, this is the main difference between hyper threading and multithreading.

Functionality

In hyper threading, a physical processor is divided into two virtual or logical processors, whereas in multithreading, a process is divided into multiple threads. Hence, this is another difference between hyper threading and multithreading.

Conclusion

The main difference between hyper threading and multithreading is that hyper threading converts a single physical processor into two virtual processors while multithreading executes multiple threads in a single process simultaneously.

Reference:

1.  Hyper Threading Explained, PowerCert Animated Videos, 25 June 2017, Available here.
2. “What Is Hyper-Threading? – Definition from WhatIs.com.” WhatIs.com, Available here.
3. “What Are Threads?” Types of Network Topology in Computer Networks | Studytonight, Available here.
4. “What Is Multithreading? – Definition from Techopedia.” Techopedia.com, Available here.

Image Courtesy:

1. “2217771” (CC0) via Pixabay
2. “Multithreading-os” By Jeff Meisel – Meisel, J. Task Parallelism, Connexions Web site. Nov 28, 2007 (CC BY 2.0) via Commons Wikimedia