Chang, Chia-Hao (Howard) Comp 1631 Winter Semester Multi-Core/Processor

Table of Contents 1.Single cores and the development from them to multicore technology 2.Multithreading, Hyper-threading, or Multi- core? 3.Single thread softwares must be replaced by multi-thread softwares for multicore technology to really show off its advantage over single core technology

Single Core Computers were first created with single core technology, where one chip only had one executing thread. Implications of such technology includes momentary freezing whenever a software is being activated for ordered to do some other action. These computer systems were only able to complete tasks one at a time.

Single Core Multi-Tasking Before the first dual core computers appeared in 2005, every computer before then could not multitask. However, programmers created the illusion that they were by using two methods: 1)Cooperative Multitasking: the first method, but was later abandoned, every application is programmed to run for an amount of cycles before stepping down for other programs in line to run. Because programs couldn’t stop until they voluntarily stepped down, this was very limited and was abandoned after Windows 95 and Apple’s Mac OS 9. 1)Pre-emptive Multitasking: the inefficiency of the first method led to the development of an operating system that had full control of which program to hand over CPU cycles. The only main inconvenience in this mode of multitasking is that sometimes programs are interrupted at inappropriate times which may lead to application failures.

Hyper Threading-Technology Intel was the first company that by 2003 released Intel Xeon processors, with Hyper-Threading Technology; a way of simultaneously processing programs. Intel proclaims that the use of hyper- threading improves speed up to 30. Not to mention, due to the extra executing thread, programs don’t need to be interrupted and switched. More important, however, two programs could now run simultaneously on a processor without having to be swapped in and out To induce the operating system to recognize one processor as two possible execution pipelines, the new chips were made to appear as two logical processors to the operating system. Hyper Threading will simulate a single processor when only one thread is present. When a second thread starts, the processor will switch from Single Thread mode to Multi-Task mode.

Multi-Core Processors Although HT technology does allow multitasking on a computer, the processor’s processing power is actually separated between the two threads. In comparison, multi-core processors are chips that have two or more cores within them.

2 is always better than 1? Although two processors can no doubt execute threads faster than one, computers are not just made of hardware. Software and hardware come hand in hand. Without multi- threading software, single threading software don’t fully benefit from multi-core processors. This is because a single threaded software can only work on one processor. Therefore the point of having two processors are nullified.

CPU-Intensive Tasks Most intensive tasks nowadays benefit from multicore processors. This may include 3D images and graphics, which are becoming quite prevalent in our time, antivirus scans, and so on.

Conclusion With the development of quad-core processors (4 cores), and hexa-core processors (8 cores), and more complex multi-thread softwares, there is no doubt that the full potential of multicores and their multi-task role will be brought into light more fully when future software run on terabytes and not mere gigabytes of information.

Bibliography Binstock, Andrew. "Multi-Core Processor Architecture Explained - Intel® Software Network."Intel Software Network Communities - Intel® Software Network. 23 Oct Web. 01 Feb "Multi-Tasking Concepts- HT, Dual Core, & Multi-Processor." Scribd. Web. 01 Feb "Multi-Core Technology." TopBits ». Web. 02 Feb