When multiple processors or processing cores in a single computer each work on a different job?

In Operating Systems, concurrency is defined as the ability of a system to run two or more programs in overlapping time phases.

As you can see, at any given time, there is only one process in execution. Therefore, concurrency is only a generalized approximation of real parallel execution. This kind of situation can be found in systems having a single-core processor.

In this Concurrency tutorial, you will learn

What is Parallel Execution or (Multi-Core)?

In parallel execution, the tasks to be performed by a process are broken down into sub-parts, and multiple CPUs (or multiple cores) process each sub-task at precisely the same time.

As you can see, at any given time, all processes are in execution. In reality, it is the sub-tasks of a process which are executing in parallel, but for better understanding, you can visualize them as processes.

Therefore, parallelism is the real way in which multiple tasks can be processed at the same time. This type of situation can be found in systems having multicore processors, which includes almost all modern, commercial processors.

• Cores increase the amount of work accomplished at a time, whereas threads improve throughput, computational speed-up.
• Cores is an actual hardware component whereas thread is a virtual component that manages the tasks.
• Cores use content switching while threads use multiple CPUs for operating numerous processes.
• Cores require only a signal process unit whereas threads require multiple processing units.

What is Thread?

A thread is a unit of execution on concurrent programming. Multithreading is a technique which allows a CPU to execute many tasks of one process at the same time. These threads can execute individually while sharing their resources.

What is Multithreading?

Multithreading refers to the common task which runs multiple threads of execution within an operating system. It can include multiple system processes.

How Multithreading Works?

For example, most modern CPUs support multithreading. A simple app on your smartphone can give you a live demo of the same.

When you open an app that requires some data to be fetched from the internet, the content area of the app is replaced by a spinner. This will rotates until the data is fetched and displayed.

In the background, there are two threads:

• One fetching the data from a network, and
• One rendering the GUI that displays the spinner

Both of these threads execute one after the other to give the illusion of concurrent execution.

What is CPU Core?

A CPU core is the part of something central to its existence or character. In the same way in the computer system, the CPU is also referred to as the core.

There are basically two types of core processor:

1. Single-Core Processor
2. Multi-Core Processor

What is the Main Issue with Single Core?

There are mainly two issues with Single Core.

• To execute the tasks faster, you need to increase the clock time.
• Increasing clock time increases power consumption and heat dissipation to an extremely high level, which makes the processor inefficient.

The Solution Provided by Multi-Core:

• Creating two cores or more on the same die to increase the processing power while it also keeps clock speed at an efficient level.
• A processor with two cores running an efficient speed can process instructions with similar speed to the single-core processor. Its clock speed is twice, yet the multicore process consumes less energy.

Benefits of Multi-core Processor

Here are some advantages of the multicore processor:

• More transistor per choice
• Shorter connections
• Lower capacitance
• A small circuit can work at fast speed

Difference between Core vs. Threads

What is Hyper-Threading?

Hyper-threading was Intel’s first effort to bring parallel computation to end user’s PCs. It was first used on desktop CPUs with the Pentium 4 in 2002.

The Pentium 4’s at that time only featured just a single CPU core. Therefore, it only performs a single task and fails to perform any type of multiple operations.

A single CPU with hyper-threading appears as two logical CPUs for an operating system. In this case, the CPU is single, but the OS considers two CPUs for each core, and CPU hardware has a single set of execution resources for every CPU core.

Therefore, CPU assumes as it has multiple cores than it does, and the operating system assumes two CPUs for each single CPU core.

Summary:

• A thread is a unit of execution on concurrent programming.
• Multithreading refers to the common task which runs multiple threads of execution within an operating system
• Today many modern CPUs support multithreading
• Hyper-threading was Intel’s first effort to bring parallel computation to end user’s PCs.
• A CPU core is the part of something central to its existence or character
• In, Operating System concurrency is defined as the ability of a system to run two or more programs in overlapping time phases.
• In parallel execution, the tasks to be performed by a process are broken down into sub-parts.
• The main issue of single-core processor is that in order to execute the tasks faster, you need to increase the clock time.
• Multicore resolves this issue by creating two cores or more on the same die to increase the processing power, and it also keeps clock speed at an efficient level.
• The biggest benefit of the multicore system is that it helps you to create more transistor per choice
• The CPU cores mean the actual hardware component whereas threads refer to the virtual component which manages the tasks.

The debate over single processor versus multi-processor CPUs is not a new one. Up until 2005, the CPU only had one core. The higher the clock speed, the better, as the fastest CPU was usually the best. However, in the last few years, CPUs have grown increasingly complex, with multiple cores enabling more performance, multitasking and other benefits. But how do we decide which is better?

Background

When you compare single processor vs multi-processor CPU, it is essential to understand what each type of chip does. These two types of CPUs are different in their processing power, but have similar uses. While a single-core CPU is responsible for processing instructions, a multi-processor chip can process many more tasks simultaneously. A single-core processor must have increased clock time to perform the same tasks.

Although high-end machines are generally better for general-purpose applications, they are less powerful than servers with single-core CPU chips. In fact, many dual-processor systems outperform their single-core counterparts. For example, a signal processing device processor might use an Arm processor with a Cortex-A general-purpose core and a Cortex-M dedicated to signal processing tasks. The simplicity of the processor cores reduces transistor count and eases power demands. Moreover, it makes the processor package cooler, which is another factor in power efficiency.

The advantages of multicore processors include improved temporal and spatial isolation. Moreover, software running on one core is less likely to affect the performance of other software. The increased isolation may improve robustness, allowing software to operate with less interference. Furthermore, it may also localize the impact of defects. These benefits may be important in mixed-critical applications. For example, when running a database, a single processor may be insufficient for the workload.

Multitasking

In computing, multitasking is the process of running more than one task on the same computer. Multicore or multi-threading processors can handle more data in the same time than single-processor CPUs, but the actual number of tasks that can be completed depends on the number of other resources on the computer. However, multitasking on single-processor CPUs can be quite beneficial.

A thread is a continuous stream of data that is generated by an application and passed through a processor. Each application generates a thread, and a single-core CPU can only handle one at a time. Multitasking allows the system to switch between threads, processing data in a seemingly simultaneous manner. Multitasking is an essential feature for modern computers. Therefore, multiprocessor CPUs offer the advantage of being able to handle many tasks at once.

In addition to the benefits of multitasking, a well-designed multitasking system will prevent a single process from gaining access to other processes’ memory. Many database management programs rely on this inter-process communication mechanism, but it’s not without its problems. Without proper memory protection mechanisms, these systems are at risk of security breaches. For this reason, many people prefer multi-processor CPUs.

Multithreading

While single-processor systems have one core, multi-processor systems have multiple cores. Thus, they can do more than one task at a time. A multi-processor system can switch between tasks, but this usually happens quickly enough that the tasks seem to be simultaneously running. However, the actual concurrency between threads differs. A multi-processor system can do a lot more than a single-processor system can handle.

Although multithreading on a single processor is similar to that on a multi-processor CPU, the main differences are in the amount of state that each thread can access. In a multi-processor system, multiple threads can share a common cache and a set of programmable registers. A single pipeline can handle multiple simultaneous tasks much faster than two or more pipelines.

When multiple threads are present on the same computer, their execution may interfere with other threads, which can lead to lower performance. The presence of a single thread can also degrade the execution speed of a program, because it requires additional pipeline stages and lower frequencies to accommodate the extra threads. However, if you use both threads on the same system, it is better to have more than one processor.

Advantages of Multithreaded Processes

One of the major benefits of a multi-processor CPU system is that it can handle more work in parallel, increasing throughput. This parallel processing – also known as threads – allows the system to complete more tasks in a shorter period of time. A multiprocessor CPU system also requires less electricity than a single-processor system, making it a more reliable option. Here are some of the advantages of multi-processor CPUs:

Multicore processors have higher clock speeds, enabling them to process more work than single-core processors. Additionally, they have multiple cores, which means the signals do not have to travel as far. In addition to this, fault-prone software is restricted to one specific core, so that it can be repaired without affecting other software. This means that multiprocessor CPUs can also withstand more faults than a single-processor CPU.

Although a multiprocessor CPU is energy efficient, there is a major caveat. Because it is possible to place multiple cores on one die, the clock speed of each core can increase substantially. However, the higher clock speed doesn’t mean that all processors are the same speed. Depending on the type of software you’re using, multi-processor systems may not be faster than a single-core model.

Disadvantages of Multithreaded Processes

Using multithreading is beneficial in many ways, but the process does have some disadvantages. First of all, threads have to be aware of shared resources and execute at the same time. This can lead to data corruption if two threads try to write to the same resource. Fortunately, a number of third-party libraries exist which provide thread-safe interfaces and pre-built support.

The CPU must spend the same amount of time on each task, irrespective of the number of threads. Multithreading allows the CPU to insert multiple things at once, improving the user experience. The CPU can then spend less time on each task, allowing the user to feel that the computer is helping them. The benefits of multithreading are well worth the trade-off.

The use of Multiprocessing helps to eliminate the previous problems. This approach allocates a specific program to each task, which can take up more memory. It is cost-efficient, and it can take advantage of multiple CPUs. However, it is not a simple process. Programmers need to be experienced to create such a complex process.

Advantages of Singlethreaded Processes

The advantages of single threaded processes over multi-processor CPUs include greater response times and the ability to more fully utilize system resources. However, it is important to remember that multithreading does not always result in better performance. For example, a process executed single-threaded must first process things in front of itself, and it will then execute the next thread. But multi-processor CPUs allow multiple threads to operate simultaneously, which will not be the case in single threaded processes.

Threads share memory with processes, but they are more susceptible to issues created by other threads within the same process. The kernel manages process threads, while threads share memory with the process they belong to. Moreover, threads are more efficient than processes, as they require less memory and resources. Thus, single threaded processes can be more efficient than multi-processor CPUs.

Disadvantages of Singlethreaded Processes

The advantages of multiprogramming are more obvious with multi-processor architectures. In contrast to single-processor architectures, which only have one processor, multi-processor CPUs can use many different threads to process data. Multi-processor CPUs enable the CPU to efficiently share memory with multiple processes. This allows more than one process to run concurrently, allowing users to feel the help of the computer.

The biggest drawback of single-processor CPUs is their limited processing power. Modern CPUs are designed to run multiple threads and processes simultaneously. Single-processor CPUs cannot do this. Each thread shares a processor’s data address space, open files, and most other resources. In a multi-processor CPU, however, two processes can share the same CPU. The CPU will then allocate a portion of its time to each task. This process is called a “time slice”, and switching between threads occurs so fast that users usually don’t notice the change.

The other disadvantage is the fact that single-processor CPUs only support one thread at a time. Unlike multi-processor CPUs, single-processor CPUs can execute many programs at once, as long as they are planned properly. Single-processor CPUs can only execute one program at a time. This is due to the fact that single-processor CPUs have one core for each application.

Conclusion

The conclusion of single processor vs multi-process or dual-core CPUs is that the latter will have faster performance than single-core CPUs. The two differ in one important way: single-core processors were fast enough to make multiple events appear simultaneously, but not fast enough to perform parallel processing. Today’s multi-core CPUs have many advantages, but they come at the expense of increased design risk.

Single-core CPUs are more expensive than dual-core ones, but they’ll give you much better performance in some software hence worth the upgrade. Because they have two physical cores, they can handle two tasks at once. However, they’re not twice as fast as dual-core processors – they get about 60 – 80% more speed. Moreover, some operating systems still use single-core processors. These operating systems run slower if they’re not compiled for dual-core processors.