PDF-Cache coherence in

sharedmemory architectures Adapted from a lecture by Ian Watson University of Machester Overview We have talked about optimizing performance on single coresLocalityVectorizationNow let us look at opt. Message Passing Sharedmemory single copy of shared data in memory threads communicate by readingwriting to a shared location Messagepassing each thread has a copy of data in its own private memory that other threads cannot access threads communicate Autumn 2006 CSE P548 Cache Coherence 6 A Lowend MP brPage 4br Autumn 2006 CSE P548 Cache Coherence 7 Cache Coherency Prot ocol Implementations Snooping used with lowend MPs few processors centralized memory busbased distributed implementation 1 1 CS448 2 What is Cache Coherence? • Two processors can have two different values for the same memory location Write Through Cache 2 3 Terminology • Coherence – Defines what va Marc De Melo. Outline. Non-Uniform Cache Architecture (NUCA). Cache Coherence. Implementation of directories in multicore architecture. 2. Non-Uniform Cache Architecture [1]. Uniform Cache Architecture. George Kurian. 1. , Omer Khan. 2. , . Srini. . Devadas. 1. 1 . Massachusetts Institute of Technology. 2 . University of Connecticut, Storrs. 1. Cache Hierarchy Organization. Directory-Based Coherence. f. or . Integrated CPU-GPU Systems. Jason Power*. , Arkaprava Basu*, . Junli. . Gu. †. , Sooraj Puthoor. †. ,. Bradford M Beckmann. †. , Mark D Hill*. †. , Steven K Reinhardt. †. , David A Wood*. Matthew D. . Sinclair et. al. UIUC. Presenting by. Sharmila. . Shridhar. SoCs. Need an . Efficient Memory Hierarchy. 2. Energy-efficient memory hierarchy is . essential. Heterogeneous . SoCs. use . Smruti R. Sarangi, IIT Delhi. Contents. Overview of the Directory Protocol. Details. Optimizations. Basic Idea of a Coherence Protocol. Memory Level . n. Memory Level . n+2. Private Cache. Private Cache. Smruti R. Sarangi, IIT Delhi. Contents. Overview of the Directory Protocol. Details. Optimizations. Basic Idea of a Coherence Protocol. Memory Level . n. Memory Level . n+2. Private Cache. Private Cache. f. or . Integrated CPU-GPU Systems. Jason Power*. , Arkaprava Basu*, . Junli. . Gu. †. , Sooraj Puthoor. †. ,. Bradford M Beckmann. †. , Mark D Hill*. †. , Steven K Reinhardt. †. , David A Wood*. :. What is Cache Coherence?. Cache Coherence: Do we need it? . Coherence Property - I:. Read R from Address X on Core C0 returns the value written by the most recent write W on X on C0, if no other core has written to X between W and R.. :. What is Cache Coherence?. When one Core writes to its own cache the other core gets to see it, when they read it out of its own cache.. Provides underlying guarantees for the programmer with respect to data validation.. wrt. . . Trace Filters. Parosh. . Aziz Abdulla. 1. , . Mohamed . Faouzi. Atig. 1. , . Zeinab. Ganjei. 2. , Ahmed Rezine. 2. . and . Yunyun. . Zhu. 1. 1. Uppsala. . University, Sweden. 2. . Lin. wrt. . . Trace Filters. Parosh. . Aziz Abdulla. 1. , . Mohamed . Faouzi. Atig. 1. , . Zeinab. Ganjei. 2. , Ahmed Rezine. 2. . and . Yunyun. . Zhu. 1. 1. Uppsala. . University, Sweden. 2. . Lin.