queueing theory in software development - alebathtub 2011-06-30
Post on 20-Oct-2014
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DESCRIPTION
This is the slides from the ALEBathtub.In this session you will learn about queuing theory and Theory of Constrains. By using real world examples of different traffic situations in Stockholm, illustrations and examples from Kanban boards you will see the similarities between them. You will lean how you can apply Theory of Constrains to find the bottleneck in your development process and how you can use this to continuously improve your development process.TRANSCRIPT
Or
What can traffic in
teach you about your
development process
Håkan Forss - [email protected] - @hakanforss
Keep work-in-progress low
Use Theory of Constraints to improve
Balance demand against throughput
Little’s Law
Work-in-Process
ThroughputCycle Time =
Little’s Law
12
12 / min1 min =
Little’s Law
6
12 / min0,5 min=
Little’s Law
24
12 / min2 min =
4 cars / min
8 cars / min
• With less work-in-progress– Shorter cycle time• Faster feedback
– Makes problems visible faster
Keep work-in-progress low
Use Theory of Constraints to improve
Balance demand against throughput
Theory of Constraints
Improve
5
1. Identify the constraint
2. Exploit the constraint
3. Subordinate to the constraint
4. Elevate the constraint
5. If in the previous steps a constraint has been broken, Go back to step 1
Don’t allow inertia to cause a system constraint.
Capacity = 6 Capacity = 4 Capacity = 6
Throughput = 4
Bottlenecks
• You can never go faster than your bottleneck
Bottlenecks
Throughput = 2
• You can never go faster than your bottleneck– Do whatever you can to make your bottleneck 100% utilized – Try your hardest to avoid problems at you bottleneck – You can’t make up for lost capacity at you bottleneck
Throughput = 4
• You can never go faster than your bottleneck– As long as capacity in front of the bottleneck is equal to or grater than the
bottleneck you will go as fast as your bottleneck– Full use of a higher capacity in front of the bottleneck will make cycle time
go up
Bottlenecks
Throughput = 4
• You can never go faster than your bottleneck– As long as capacity is equal to or grater after the bottleneck you will go as
fast as your bottleneck– Higher capacity after the bottleneck than at the bottleneck will not improve
throughput
Bottlenecks
• Non-instant availability resource– A resource that is not available all the time
• Non-instant availability resource & bottleneck
Keep work-in-progress low
Use Theory of Constraints to improve
Balance demand against throughput
• You can never go faster than your bottleneck– Balance demand against throughput to keep work-in-progress low– Low work-in-progress
• Keeps cycle time down • Makes bottlenecks visible faster
• Slow down to go faster – Slowing down can stabilize the process flow– A stable process can go faster
Keep work-in-progress low• Keeps cycle time down • Makes bottlenecks visible faster
Use Theory of Constraints to improve• Use five focusing steps• Eliminate one bottleneck at a time
Balance demand against throughput • You can’t go faster than the bottleneck• Use work-in-progress limits
Håkan ForssMail: [email protected]: @hakanforssBlog: http://hakanforss.wordpress.com/