PPT-Cache Coherence Protocols

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. For each of the approaches the associated protocol is outlined The simulation model is described and results from that model are presented The magnitude of the potential performance difference between the various approaches indicates that the choice 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 -Client Pairing: A Framework for Implementing Coherence Hierarchies. Jesse G. Beu. Michael C. Rosier. Thomas M. Conte. Tinker Research. Georgia Institute . of Technology. The Problem. Coherence protocols can be difficult to design properly. 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*. CS 15-440. Consistency and Replication – Part IV. Lecture 13, Oct 23, 2013. Mohammad . Hammoud. Today…. Last Session:. Consistency and . Replication- Past III. Client-centric consistency models and replica management. Topics: snooping-based cache coherence implementations 2Design Issues, Optimizations demotion from modified to shared?move from modified in one cache to modified in another?Who responds with data? &# Dept. of Electrical & Computer Engineering. Computer Architecture . ECE 668. Multiprocessor Systems. Csaba Andras Moritz. Textbook: Dubois, . Annavaram. , . Stenstrom. , Parallel Computer Organization and Design. 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?. 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. 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