Pipelining defines the temporal overlapping of processing. Pipelines are emptiness greater than assembly lines in computing that can be used either for instruction processing or, in a more general method, for executing any complex operations. It can be used efficiently only for a sequence of the same task, much similar to assembly lines.A basic pipeline processes a sequence of tasks, including instructions, as per the following principle of operation −Each task is subdivided into multiple successive subtasks as shown in the figure. For instance, the execution of register-register instructions can be broken down into instruction fetch, decode, execute, and writeback.A ... Read More

When instructions are handled in parallel, it is required to detect and resolve dependencies between instructions. It can generally discuss dependency detection and resolution as it associates to processor classes and the processing functions contained independently.An instruction is resource-dependent on an issued instruction if it needed a hardware resource that can be utilized by a previously issued instruction. If, for instance, only a single non-pipelined division unit is accessible, as in general in ILP-processors, thus in the code sequence the second division instruction is resource-dependent on the first one and cannot be implemented in parallel.Resource dependencies are constraints generated by ... Read More

Consider the following code sequence −mul r1, r2, r3; jz  zproc; sub r4, r7, r1; : zproc:load r1, x; :In this example, the real direction of implementation depends on the result of the multiplication. This represents that the instructions following a conditional branch are dependent on it. In a similar method, all conditional control instructions, including conditional branches, calls, skips, etc. promulgate dependencies on the logically subsequent instructions is known as control dependencies.The term general-purpose program stands for compilers, operating systems, or non-numeric application programs. The data indicates that that general-purpose program has a high percentage of branches, up to ... Read More

A position in which an instruction is dependent on a result from a sequentially earlier instruction before it can be done its execution. In high-performance processors operating pipeline or superscalar techniques, a data dependency will learn an interruption in the flowing services of a processor pipeline or prevent the parallel issue of instructions in a superscalar processor.Consider two instructions ik and ii of the same program, where ik precedes ii. If ik and ii have a common register or memory operand, they are data-dependent on each other, except when the common operand is used in both instructions as a source ... Read More

There are two types of operations of ILP-Processors such as Pipelined Processors and VLIW and Superscalar Processors. Pipelined Processors work like an assembly line, both VLIW and Superscalar processors operate basically in parallel, making use of several concurrently working EUs as shown in the figure −In describing the principle of operation of pipelined processors, for simplicity, it can confine itself to a straightforward pipelined processor which executes integer, RISC-like, register-register instructions. Pipelines like these operate along the following lines −Instruction processing is subdivided into several successive subtasks: instruction Fetch (F), Decode (D), Execute (E), and writeback of the result (W), ... Read More

The evolution of Von Neumann processors can be attributed to two areas of development improvement in technology, marked by increasing clock rates and the functional evolution of processors. Functional evolution has been achieved primarily by increasing the degree of parallelism of the internal operations, the issues, and the execution of instructions.This occurred in three consecutive evolution phases as the first phase is represented by traditional von Neumann processors, which are characterized by sequential issues and sequential execution of instructions as shown in the figure.The search for greater implementation gave advance to the introduction of parallel instruction execution. Parallel execution was ... Read More

There are two methods of exploiting parallelism in parallel computer architecture are as follows −PipeliningIn pipelining, several functional units are working in sequence to implement a single computation. These functional units form an assembly line or pipeline. Each functional unit describes a specific phase of the computation and each computation goes through the entire pipeline.If there is only a single computation to be executed, the pipeline cannot extract any parallelism. But, when the same computation is to be implemented multiple times, these computations can be overlapped through the functional units.Assume that the pipeline consists of N functional units (stages) and ... Read More

Flynn’s classic taxonomy (Flynn, 1966) depends on the number of control units and the multiple processors available in a computer. Flynn’s introduced the following notions −Single Instruction StreamSingle Instruction stream means that architecture has a single control unit generating a single stream of instruction abbreviated as single instruction SI.Multiple Instruction StreamMultiple Instruction Stream means that architecture has multiple control units each producing has a distinct stream of instruction abbreviated as MI.Single Data StreamA single data stream is a single processor available which will execute a single stream of data abbreviates as SD.Multiple Data StreamIn multiple data streams, there are multiple ... Read More

There are various types of Parallelism in Computer Architecture which are as follows −Available and Utilized ParallelismParallelism is the most important topics in computing. Architectures, compilers, and operating frameworks have been striving for more than two decades to extract and use as much parallelism as available to speed up computation.Available and Utilized ParallelismParallelism is the most important topics in computing. Architectures, compilers, and operating frameworks have been striving for more than two decades to extract and use as much parallelism as available to speed up computation.Functional Parallelism is that type of parallelism that raise from the logic of a problem ... Read More

Concurrency ExecutionIt is the sensual behavior of the N-Client I-Server model where one client is served at any provided moment. This model has dual characteristics. It is sequential on a small time scale, but together on a rather large time scale.In this method, the elementary problem is how the competing clients, processors or threads, must be scheduled for service (Execution) through the single-level (processor). Scheduling policies can be oriented toward efficient service in terms of highest throughput (least intervention) or towards short average response time, and so on.The scheduling policy can be considered as covering two methods as first deals ... Read More