Multicore Processor Architecture

 Scheduling of multicores The scheduling of multi core is performed in such a manner that the real time tasks do not miss their deadlines. The scheduling of multicore includes two types of scheduling: Partitioned scheduling and Global scheduling. In partitioned scheduling different tasks are assigned to cores statically and they are not allowed to migrate from one core to another. The partitioned scheduling is advantageous as there is no migration overhead. But, the use of partitioned scheduling suffers two major disadvantages (a) This scheduling scheme is inflexible in nature and cannot easily accommodate dynamic tasks without a complete re-partition. (b) It is related to optimal assignment of tasks to cores which creates an NPhard problem for which polynomial-time solutions result in sub-optimal partitions. Factors affecting performance of multicore processor The performance of the multicore processor is good if the CPU is utilized properly and the desired outcome is pro...

1) Cache related issues:     i) Amount of cache: The size of cache required for a multicore processor is application dependent. The application where the data reusability is more it is preferred to use big cache. Bigger the size of cache faster will be the speed of accessing and better will be the performance but higher will be the cost. ii) Number of cache levels: Another cache issue is to decide the number of cache levels a cache of multicore may have. It is not necessary for the entire cores cache to have equal number of cache levels. Basically the number of cache levels is decided by how far the main memory is or how many cycles will it take to access the main memory. More the number of cycles more will be the cache levels and faster is the accessing. iii) Deterministic/nondeterministic performance: In some applications the caches are tagged and managed either by the hardware itself or its local memory. In case of hardware managed tags the tags are stored on...

  On the basis of common features or characteristics the multicore processor architecture can be broadly classified as : application class, power/performance, processing elements, memory system, and accelerators/integrated peripherals. i ) Application Class : In this the architecture of multicore processor is mainly focused on the requirement of specific application domain. This results in several positive outcomes but often the multicore for a particular application domain cannot be used or have adverse effects when used in other domains. An application may fall in one of the two classes in their execution phase: data processing dominated and control processing dominated. In data dominated the operations are performed on a set of data with little or no data reusage. This fact gives the processing to be performed in parallel with high throughput and performance for a large data. Some of the applications are image processing, audio processing, wireless base band processing etc. In c...

  Multicore processor gives the functionality of parallel processing with reduced sustainable computation time. In present scenario of multicore, the two main challenges that need to be addressed are: to meet the increased demand of high computing processors and reduced battery power of the processor that helps such systems to be mobile across the globe. These two challenges are counterproductive as if one is addressed the other becomes worsen and vice versa. Internal Structure Multicore processors can be defined as a system whose central processing unit is divided into many logical parts called core and each core may have one or more private caches as shown in figure 1. The figure shows four cores having one or more caches and each core is connected via an interconnection network to the memory of the system.   The inside view of a single core is shown in figure. The figure  shows a processor with a single core consisting of a private cache L1 and a shared cache L2 . Th...