1. Overview of the Lab 2 Assignment: Linux Scheduler Profiling
James Orr, Chris Gill
CSE 422S - Operating Systems Organization
Washington University in St. Louis
St. Louis, MO 63143

2. Experiment Configuration
We will pin a number of threads on each core (enough to examine scheduler differences in various ways)
Threads will access a common shared data structure
Grabbing a new number at the start of each “round”
Incrementing (safely) a variable pointing to next number
Cubing the selected number over and over again
Very basic functionality
Synthetic workload
Interleaving simple steps
Configurable experiments
Shared
data
CSE 422S – Operating Systems Organization

3. User Space Program
You can use any language you like (e.g. C++) … … as long as it can do what is required
Thread creation and
binding to cores
Synchronization
Appropriate setting
of scheduler, priorities
spinning
sleeping
Run your program repeatedly
In different configurations
Analyze and show the results
Give instructions for how to run
So we can reproduce your trials
So we can try other variations
CSE 422S – Operating Systems Organization

4. CSE 422S – Operating Systems Organization
Concurrency Behavior
All threads should first barrier synchronize
May need condition variable for sleep version
No thread starts cubing until all are ready
Afterward, threads should run concurrently
As soon as all threads are ready, they should run concurrently, each doing rounds of iteratively cubing a number
Synchronization while cubing
Need to avoid data races, especially when updating variables other threads can read
Make critical sections as short as possible (“lock data, not code”)
Avoid unnecessary sharing of variables
(use stack variables as needed)
Lock access to variables that must be shared
CSE 422S – Operating Systems Organization

5. CSE 422S – Operating Systems Organization
Lab Write-up
As you work, record your observations along with answers to the questions posed in the lab assignment
It’s a good idea to read the entire assignment and plan a bit before starting to work on it
Write a cohesive report that analyzes, integrates, and offers explanations for what you observed
Make connections among different parts of the assignment
Compare and contrast different schedulers behaviors
Identify how different factors affected scheduler behaviors
CSE 422S – Operating Systems Organization