multi processor system
In order to increase the performance of computer systems, several processors are interconnected by a communication network. This processor concept is called a multiprocessor system. For this system application, well-known processors are used which are also used in single-processor systems. Functions for multiprocessor operation are already integrated in these processors.
Multiprocessor systems operate either with a central memory system to which all processors have direct access, or with distributed memories. In this case, each processor is assigned its own memory which only it can access. Data from another memory can only be requested via the responsible processor.
Which multiprocessor concept can be used depends mainly on the available memory bandwidth and the delay times caused by accessing the memory.
In the architecture with a central memory, where each processor can access it, the memory bandwidth does not increase with the number of processors. For this reason, each processor is provided with its own cache in this concept. This compensates for waiting and delay times, since the amount of data that has to be transported over the network is reduced.
In the distributed memory concept, sufficient memory bandwidth is available to each processor, which means that delay times are lower than in the central memory concept. However, this only applies to the data that is available to each processor. If a processor needs data from another memory, this requires communication, which limits the previously mentioned advantage. If the multiprocessor systems are symmetrical, they are called Symmetric Multiprocessor( SMP).