Improving Instruction Cache Performance in OLTP

1. Improving Instruction Cache Performance in OLTP Submitted By, Ravali Chalasani 2459929

2. Key Terms OLTP Cache Performance

3. Online Transaction Processing (or OLTP) is a class of programs that facilitate and manage transaction-oriented applications, typically for data entry and retrieval transaction processing. • Benefits: • Online Transaction Processing has two key benefits: simplicity and efficiency. • Disadvantages: • It is a great tool for any organization, but in using OLTP, there are a few things to be wary of: the security issues and economical costs.

4. Cache Performance : Average memory access time is a useful measure to evaluate the performance of a memory-hierarchy configuration. It tells us how much penalty the memory system imposes on each access (on average). An Example :- Compare the performance of a 64KB unified cache with a split cache with 32KB data and 16KB instruction . The miss penalty for either cache is 100 ns, and the CPU clock runs at 200 MHz.

5. Optimizing Instruction Cache Performance :- • High Instruction Cache rates are key to high performances. • To improve the hit rate of caches is to minimize cache interference by improving the layout of the basic block of codes. • Good instruction cache performance is very important in modern DBMS installations while running OLTP applications.

6. Methods used to improve Cache performance : • STEPS - to increase instruction locality in database servers. • autoSTEPS - is a code profiling tool that automates the application of STEPS for any database systems. • The effectiveness of out approach is Demonstrated on Shore - which is a research prototype database system.

7. Background and Related work : • To bridge the CPU/Memory performance today systems use hierarchy of caches. • Example : IBM’s Power5 • Problems: • The Instruction Cache Performance. • Database Workloads.

8. Introducing CACHE-Resident code “ STEPS” • All OLTP transactions regardless of the specific action execute common database mechanisms. • Basic implementation of STEPS:- • Begin, Commit, Index Fetch, Scan, Update, Insert, Delete. • Context-Switching:- • Switching execution from one thread/ process to another involves updating OS and DBMS software structures and CPU registers.

9. Applying STEPS to OLTP workloads :- • Full STEPS implementation • Scheduling execution teams. • Maximizing code overlap across transactions

10. Applicability to Commercial DBMS :- • STEPS has two attractive features: • It applies incrementally to the target specific code • The required code modifications are restricted to a specific small subset of code. • We use autoSTEPS as a tool to Generate CTX insertion points.

11. Contributions:- • A novel technique that enables thread scheduling at very fine granularity to reuse instructions in the cache across concurrent threads. • A tool to automatically find points in the code that the instruction cache fills up. • The implementation and evaluation of the presented techniques inside the research prototype database systems.

12. Conclusion :- • The whole article is about the implementation of STEPS which is a transaction coordinating mechanism that addresses the instruction-cache bottleneck in OLTP workloads. • STEPS is a mechanism that can be applied with few code changes to any database software.

13. QUESTIONS?????