1 / 9

Symmetric and CC-NUMA

Symmetric and CC-NUMA. Scope. Design experiences of SMPs and Coherent Cache Nonuniform Memory Access (CC-NUMA) NUMA Natural extension of SMP systems. Processor & Cache. Processor & Cache. Processor & Cache. Processor & Cache. . . . . . . Interconnect. Bus/Crossbar. Memory. Memory.

florida
Download Presentation

Symmetric and CC-NUMA

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Symmetric and CC-NUMA

  2. Scope • Design experiences of SMPs and Coherent Cache Nonuniform Memory Access (CC-NUMA) • NUMA • Natural extension of SMP systems

  3. Processor & Cache Processor & Cache Processor & Cache Processor & Cache . . . . . . Interconnect Bus/Crossbar Memory Memory I/O I/O Processor & Cache Processor & Cache Processor & Cache Processor & Cache . . . . . . Bus/Crossbar Bus/Crossbar Memory Memory Remote Cache Remote Cache I/O I/O Architectures Shared Memory logic structure SMP architecture . . . Node 1 Node N

  4. Advantages of shard memory systems (SMP or CC-NUMA) • Symmetry • Any processor can access any memory location and I/O device • Single address space • Single system image • One copy of OS, database app, etc • Reside in the shared memory • User no control over data distribution, redistribution • Single OS schedules processes • Easy workload management, dynamic load balancing

  5. Advantages of shard memory systems (SMP or CC-NUMA) • Caching • Data locality supported in the hierarchy • Coherency • Enforced by the hardware? • MESI-like snoopy protocol • Memory Communication • Low latency • Simple load/store instructions • Hardware generates coherency information

  6. Basic Issues that SMPs must address • Availability • Biggest problem • Failure of the bus, memory, OS !! • Bottleneck • Compete for the memory bus and shard memory • Packet switched-bus (split transactions) • Latency • Low latency but still large compared to CPU • Memory bandwidth vs. Processor speed vs. Memory capacity • Scalability • A bus is not scalable

  7. CC-NUMA • Extends SMPs by connecting several SMP nodes into a larger system • Employ directory based cache coherent protocol • While maintaining the advantages, attacks the scalability problem

  8. Distributed shared memory enhances: • Scalability • Memory capacity, I/O capabilities increase by adding more nodes • Bandwidth • An app can access multiple local memories concurrently • Availability • Multiple copies of a portion of OS can run on multiple nodes • Failure of one will not disrupt the entire system

  9. Programming • We said that • “data structures get distributed” • “Cache coherency then tracks the changes” • Any issues? (remote cache vs local memory) • P, Q: processes • A, B: arrays P: Q: Phase 1: use(A) use(B) Phase 2: use(B) use(A)

More Related