what are cpu cores ?
cpu cores :
Origins:
The term "multi-heart" is used to describe a processor of at least two cores (or processing units) engraved in the same chip.
We owe to IBM the first multi-processor have been marketed to heart: this is the POWER4 , in 2001.
The first examples of multi-core processors from Intel and AMD have entered the PC market in 2005 . It was homogeneous cores, that is to say identical. The case of different cores and specialized in specific areas (audio, display, computational, etc.) has been exploited to the processor Cell designed by IBM , Sony and Toshiba . This architecture allows to increase computing power without increasing the clock frequency , thereby reducing the amount of heat dissipated by Joule effect (as for systems multiprocessor ).
The first chips based on double heart x86 appeared in 2005 on the server market ( Opterons AMD). They appeared because in practice the race GHz has become too burdensome and complicated. The generation of processors that time had only one heart and had a consumer could easily exceed 100 W (including processors Intel Pentium 4 ). She had to face serious problems of cooling circuits . The solution that seemed most obvious was to favor either the frequency, but to increase the power through a parallel architecture, so as to increase the number of overlapping operations in one clock cycle.
Evolution of Technology :
Since launching the first computer on the market, demand for computing power have become increasingly important. Symmetric multiprocessing ( SMP ) has long been used to improve performance and efficiency by spreading computing loads across multiple CPUs. The SMP is particularly effective in environments where multiple multithreaded tasks (processes) must be managed simultaneously.
With the changing demands of application performance, processor designers are facing a problem: The increase in computing capacity is dependent on the power, and the fact of increasing the power required to manage both levels of dissipation. Added to this are the demands of industrial computers that want less space, ie more servers per rack, laptops thinner and lighter, and a smaller footprint for desktop systems. While multi-heart contributes to meeting these challenges. This technological development increases performance and productivity in smaller computers that can run multiple complex applications and perform more tasks in less time.
Main Asset :
In today's digital world, the demand for simulations complex 3D files multimedia streaming, additional levels of security, interfaces, more sophisticated user, databases larger and larger number of users online is beginning to overwhelm mono-core processors.
The multi-core processors favor a true multi-tasking. On single-core systems, multitasking can exceed the capabilities of the CPU , resulting in decreased performance due to the queuing operations to be processed. On multi-core systems, since each heart has its own cache , the operating system has enough resources to handle parallel tasks in the most demanding calculations.
The multi-heart can improve system efficiency and increase application performance for computers running multiple applications simultaneously.
The software constraints :
Unfortunately, this approach has some disadvantages, since the programs must be redesigned to fully exploit the features of these processors. Otherwise, they use only one heart, causing a decline in performance relative to expectations.
In 2006 , very few software handles the dual-core, and overall the software is not designed to make the most of this technology (except in GNU / Linux, where applications are made in vast majority-nearly 99, 8% - in several types of architectures). Once completed an upgrade of all programs to the new architecture, the performance will stand out clearly in demanding applications such as video games . Ultimately, the quad-core, consisting of 4 cores, will replace the dual-core, because the transition to this architecture does not require hardly any software modification.
The telecommunications market has been one of the earliest adopters of multi-core processors, for both data transport layer for the control layer. Since then, the MPU are rapidly replacing the network processors (NP) which were based on proprietary architectures based firmware and picocode. 6WIND was the first company to provide embedded networking software optimized for these multi-core architectures.
Parallel programming also benefits directly from multiple cores. Programming models like OpenMP , MPI or OpenHMPP can be used on these platforms multicore. Other research efforts are also conducted, for example the system Codeplay Sieve, languages Ateji PX, Chapel (in) of Cray , Fortress of Sun and X10 from IBM .
Multi-core Processors existing :
There are currently several architectures of multicore processors. Besides the models of Intel and AMD already mentioned, Sun Microsystems has developed its range Niagara and Niagara II , IBM has developed its range of PowerPC and online CellBE , marketed by IBM as blade server, by Mercury in the form of reinforced chassis .
The industry is at the same time to multiply the number of processor cores on a processor such as Intel 's project in Tera-Scale .
