CS457 - System Performance Evaluation - Winter 2008


1. Textbook


Lecture 4 - Performance Metrics

Creating an Abstraction

Section 2.2: 1-5 & 7

Two example systems

  1. RPC versus Remote pipes
  2. E-commerce server
Stage RPC E-commerce
1. Define Goals, System
  • goals first
  • minimize system size
Write a paper comparing RPC to RPs
  • System should include overhead.
  • System should not include computation
Ensure that a system architecture is scalable.

Find the right size for an expected workload

2. List services
  • possible outcomes for each service
  • including failures
Data transfer (why?)
  • large transfers
  • small transfers
  • failures omitted (why?)
Catalogue updates

Client requests

  • etc.
3. List metrics
  • speed
  • accuracy
  • availability
4. List parameters
  • that affect performance as defined by metrics
5. Select factors to study
  • What about the other parameters?
6(7). Select workload
  • measurement: scripted, usually with randomness, could be a trace or log

Metrics

Sequence of events for a single request

  1. System receives request, ai
  2. System starts executing the request - reaction time
  3. System starts responding to request - response time 1
  4. System completes response to request, di - response time 2, ri = di - ai

Types of metrics

  1. Speed
  2. Accuracy
  3. Availability

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