Microprocessor - Multicore Designs

Multicore Designs

A different approach to improving a computer's performance is to add extra processors, as in symmetric multiprocessing designs, which have been popular in servers and workstations since the early 1990s. Keeping up with Moore's Law is becoming increasingly challenging as chip-making technologies approach their physical limits.

In response, microprocessor manufacturers look for other ways to improve performance in order to hold on to the momentum of constant upgrades in the market.

A multi-core processor is simply a single chip containing more than one microprocessor core. This effectively multiplies the processor's potential performance by the number of cores (as long as the operating system and software is designed to take advantage of more than one processor core). Some components, such as bus interface and cache, may be shared between cores. Because the cores are physically very close to each other, they can communicate with each other much faster than separate processors in a multiprocessor system, which improves overall system performance.

In 2005, the first personal computer dual-core processors were announced. As of 2012, dual-core and quad-core processors are widely used in home PCs and laptops while quad, six, eight, ten, twelve, and sixteen-core processors are common in the professional and enterprise markets with workstations and servers.

Sun Microsystems has released the Niagara and Niagara 2 chips, both of which feature an eight-core design. The Niagara 2 supports more threads and operates at 1.6 GHz.

High-end Intel Xeon processors that are on the LGA 771, LGA1336, and LGA 2011 sockets and high-end AMD Opteron processors that are on the C32 and G34 sockets are DP (dual processor) capable, as well as the older Intel Core 2 Extreme QX9775 also used in an older Mac Pro by Apple and the Intel Skulltrail motherboard. AMD's G34 motherboards can support up to four CPUs and Intel's LGA 1567 motherboards can support up to eight CPUs.

The modern desktop sockets do not support systems with multiple CPUs but very few applications outside of the professional market can make good use of more than four cores and both Intel and AMD currently offer fast quad and six core desktop CPUs so this is generally a moot point anyway. AMD also offers the first and still currently the only eight core desktop CPUs with the FX-8xxx line but anything with more than four cores is generally not very useful in home desktops. As of January 24 of 2012, these FX processors are generally inferior to similarly priced and sometimes cheaper Intel quad core Sandy Bridge models.

The desktop market has been in a transition towards quad core CPUs since Intel's Core 2 Quads were released and now are quite common although dual core CPUs are still more prevalent. This is largely because of people using older or mobile computers, both of which have a much lower chance of having more than two cores than newer desktops and because of how most computer users are not heavy users. AMD offers CPUs with more cores for a given amount of money than similarly priced Intel CPUs but the AMD cores are somewhat slower than Intel cores so the two will trade blows in different applications depending on how well threaded the programs being used are.

For example, Intel's cheapest Sandy Bridge quad core CPUs often cost almost twice as much as AMD's cheapest Athlon II, Phenom II, and FX quad core CPUs but Intel has dual core CPUs in the same price ranges as AMD's cheaper quad core CPUs. In an application that uses one or two threads the Intel dual cores will out-perform AMD's similarly priced quad core CPUs and if a program supports three or four threads the cheap AMD quad core CPUs will out-perform the similarly priced Intel dual-core CPUs.

Historically AMD and Intel have switched places as the company with the fastest CPU several times. Intel is currently winning on the desktop side of the computer CPU market with their Sandy Bridge and upcoming Ivy Bridge series. In servers AMD's new Opterons seem to have superior performance for their price points. This means that AMD is currently more competitive in low to mid end servers and workstations where more cores and threads are more effectively utilized since professional software often uses more, if not all available threads.