This is a basic implementation of lottery scheduling to understand the impact of compensatory tickets.
1 // use compensatory tickets or not
10 // quantum
5 // number of iterations to run of the main scheduling loop
2 // number of users
Amy // user name
150 // lottery tickets
4 // number of jobs
15 15 15 15 // work per job
Bob // ...
100
3
20 20 20
Here is a sample output from such a file:
Quantum is 10 (Comp tickets set to: true)
User: Amy (150 tickets) has jobs:
Job 0
Work: 15
Remaining: 15
Job 1
Work: 15
Remaining: 15
Job 2
Work: 15
Remaining: 15
Job 3
Work: 15
Remaining: 15
User: Bob (100 tickets) has jobs:
Job 0
Work: 20
Remaining: 20
Job 1
Work: 20
Remaining: 20
Job 2
Work: 20
Remaining: 20
At time: 0, the winner was: Amy
At time: 10, the winner was: Amy
At time: 15, the winner was: Bob
At time: 25, the winner was: Bob
At time: 35, the winner was: Amy
There were 5 lotteries
User: Bob won 2 times (expected 2.00)
User: Bob performed 20 units of work (44.44%)
User: Amy won 3 times (expected 3.00)
User: Amy performed 25 units of work (55.56%)
To build, simply clone this directory and run cargo build.
To run, you can either use the executable directly or do cargo run < sample.txt or whatever
input file you'd like.
The sample file could be tweaked to have a different quantum, turn on/off compensatory tickets,
change the jobs each user submits, change the number of users, etc.
For instance, in sample2.txt we added another user Carol:
1
10
20
3
Amy
150
4
15 15 15 15
Bob
100
3
20 20 20
Carol
200
1
60
Which generated the following trace:
Quantum is 10 (Comp tickets set to: true)
User: Amy (150 tickets) has jobs:
Job 0
Work: 15
Remaining: 15
Job 1
Work: 15
Remaining: 15
Job 2
Work: 15
Remaining: 15
Job 3
Work: 15
Remaining: 15
User: Bob (100 tickets) has jobs:
Job 0
Work: 20
Remaining: 20
Job 1
Work: 20
Remaining: 20
Job 2
Work: 20
Remaining: 20
User: Carol (200 tickets) has jobs:
Job 0
Work: 60
Remaining: 60
At time: 0, the winner was: Amy
At time: 10, the winner was: Bob
At time: 20, the winner was: Bob
At time: 30, the winner was: Carol
At time: 40, the winner was: Carol
At time: 50, the winner was: Bob
At time: 50, the winner was: Carol
At time: 60, the winner was: Amy
At time: 65, the winner was: Carol
At time: 75, the winner was: Amy
At time: 85, the winner was: Amy
At time: 90, the winner was: Carol
At time: 100, the winner was: Bob
At time: 110, the winner was: Carol
At time: 120, the winner was: Amy
At time: 130, the winner was: Carol
At time: 130, the winner was: Amy
At time: 135, the winner was: Amy
At time: 145, the winner was: Bob
At time: 155, the winner was: Bob
There were 20 lotteries
User: Bob won 6 times (expected 4.44)
User: Bob performed 40 units of work (25.81%)
User: Amy won 7 times (expected 6.67)
User: Amy performed 55 units of work (35.48%)
User: Carol won 7 times (expected 8.89)
User: Carol performed 60 units of work (38.71%)
In section 3.4 of the Lottery Scheduling paper the authors explain compensation tickets:
A client which consumes only a fraction f of its allocated resource quantum can be granted a compensation ticket that inflates its value by 1/f until the client starts its next quantum. This ensures that each client’s resource consumption, equal to f times its per-lottery win probability p, is adjusted by 1/f to match its allocated share p. Without compensation tickets, a client that does not consume its entire allocated quantum would receive less than its entitled share of the processor.