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Memory System Characterization of Commercial Workloads

Memory System Characterization of Commercial Workloads. Luiz Andre Barroso, Kourosh Gharachorloo, and Edouard Bugnion Presented by Jerry Wu. Introduction. Motivation Commercial workloads has become the largest market segment for multiprocessor servers

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Memory System Characterization of Commercial Workloads

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  1. Memory System Characterization of Commercial Workloads Luiz Andre Barroso, Kourosh Gharachorloo, and Edouard Bugnion Presented by Jerry Wu

  2. Introduction • Motivation • Commercial workloads has become the largest market segment for multiprocessor servers • Design of these systems has yet to keep up with the pace of changes in the market • Lack of commercial workload performance requirements • This paper presents performance studies of three classes of commercial workloads

  3. Complications • Lack of availability and restrictions • Lack of easy access to commercial database engines • Large scale • Large hardware cost • Complexity • Non-trivial OS-I/O interactions, lack of source code • Moving target • Commercial database engines improve at a very fast pace

  4. Commercial Workloads • OLTP Workload • Modeled after the TPC-B benchmark • Models a banking system • DSS Workload • Modeled after the TPC-D benchmark • Simulates the decision support system for a supplier • OLTP and DSS workloads run on Oracle Database Engine • Web Index Search Workload • State-of-the-art search engine AltaVista (No Google yet)

  5. Methodology • Monitoring • OLTP and DSS benchmarks were run on Alpha 21164 using Oracle • Utilized IPROBE monitoring tool to access event counters • Simulation • Used an Alpha port of SimOS • Key issues • Amount of physical memory required • Bandwidth requirement for the I/O • Total runtime

  6. Monitoring Results • OLTP • Importance of hits and misses to secondary caches and latency of dirty misses • DSS and AltaVista • Hits in secondary on-chip cache is the only significant memory component

  7. Simulation Results • Uses an Alpha port of SimOS • Observations on OLTP • Small kernel component • Benefit from larger cache and higher associativity • Cache and memory system stalls have large effects • Idle time increases with bigger caches • Higher processing rates results in less demand on I/O • Small fraction of communication in Oracle due to false sharing

  8. Cache Hierarchy Performance • Primary cache miss important for OLTP, but more so for DSS • OLTP and DSS have very different cache performance • Large on-chip cache captures most of the misses in DSS, but not in OLTP • False sharing increases for increasing cache line size • Replacement and instruction miss rate not visibly effected

  9. Questions

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