CA presentation of multicore processor
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Multi-core processors have multiple processing units (cores) on a single chip to improve performance over single-core processors. As clock speeds became limited, chip designers added multiple cores to allow simultaneous execution of instructions. This achieves performance gains without increasing heat and power consumption. However, multi-core processors introduce new challenges around cache coherence and ensuring software is optimized for parallel execution across multiple cores. Future multi-core designs may include heterogeneous cores specialized for different tasks to further improve efficiency.
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CA presentation of multicore processor
- 1. Multi-core Processors A COMPARATIVE ANALYSIS BETWEEN SINGLE CORE AND MULTI-CORE PROCESSORS
- 2. Outline 1. Introduction 2. Single Core Performance 3. Problems with Single Core 4. Multi-core Solutions 5. Multi-core Advantages 6. Other Incentives 7. Cache Memory in Multi-core Architecture 8. Problems 9. Future of Multi-core
- 3. What is a Core ? ◦ A Basic Computational Unit of a CPU. ◦ A Core receives instructions, work on it and give results. ◦ A Core is a collection of components such as ALU ( Arithmetic and Logic Unit ), Registers and Cache memory. ◦ It can run a single thread at a single time. ( Unless it is a Multithreaded Core, which we'll see in a bit ). ◦ A thread is a small group of instructions with its own PC ( Program Counter ).
- 4. Single Core Processors ◦ Before the multi-core era, all the processors used to consist of a single core. ◦ A single Core processor is a microprocessor with a single core on the CPU chip. ◦ It can run a single thread at any one time. ( unless Multithreaded ). ◦ With the passage of time the processors became smaller in size, faster and more efficient.
- 6. Single Core Performance ◦ Back in that time performance comparisons were based on the clock speeds of the processors. ◦ Performance gains were achieved by increasing the clock rate of the processor. ◦ Higher the clock speed faster the execution of instructions. ◦ Apart from clock speed execution optimization and cache were also major areas of performance gains in single core processors. ◦ Several execution optimization techniques were introduced such as pipelining and multithreading. ◦ This trend continued for many years.
- 7. Single Core Performance contd. ◦ Pipelining was introduced for execution optimization.
- 8. Single Core Performance Contd. ◦ Another technique that was introduced was Multithreading. ◦ Multithreading involves execution of two separate threads. ◦ Time is divided and interlaced between the two threads in order to simulate simultaneous execution.
- 9. Single Core Problems ◦ In order to execute tasks even faster you must increase the clock speed but there is a problem. ◦ The clock speed has reached its limit. ◦ Increasing clock speeds too high increases power consumption and heat dissipation to extremely high levels. ◦ Different designs are needed which is risky and time consuming. ◦ Cost is also a major factor.
- 11. Multi-core Processors ◦ The solution came with the introduction of multicore processors. ◦ When increasing the clock speed was no longer an option the chip designers came up with the idea of incorporating more than one core on a CPU chip to improve performance. ◦ Creating two cores on a single chip increases performance by keeping clock rates at an efficient level. ◦ A processor with 2 cores and an efficient clock rate can execute instruction with similar speed to a single core processor running at twice the clock rate. ◦ The processor with two cores will consume less energy.
- 14. Advantages of Multi-core ◦ Simultaneous Execution ◦ Higher Performance ◦ Instruction Level Parallelism ◦ Lesser Heat Generation ◦ Multithreaded Applications ◦ Thread Level Parallelism
- 15. Cache memory in Multi-core Architecture ◦ The first Level ( L1 ) cache is always dedicated to all cores, because it needs to be accessed quickly. ◦ The Last Level of cache is shared between all the cores. ( Usually they are L2 or L3 ). ◦ Middle Level Caches can either be shared or merged.
- 17. Problems and Challenges ◦ Memory / Cache coherence problem. Because we have separate caches for separate core, how to keep data consistent across caches ? ◦ Multithreading is also a problem, because the software running may not be designed to take advantage of multicore processor. ◦ This means that a single core does most of the work and the processor is running no more efficient than a single core processor.
- 18. The Cache Coherence Problem
- 24. Future of Multi-core Processors ◦ The Future Multi-core Processors may be Heterogeneous. ◦ Which means all the cores on the chip could be of different types. ◦ Having different cores that specialized in different tasks increases complexity but has the potential of being much more efficient in speed and power consumption. ◦ If an application only needs to run on a specific kind of a core, performance will be better.
- 25. Thank You.