Unity3d method invocation profiling
I thought it would be interesting to see how expensive method calls are in comparison to eachother so here’s a profiler session comparing a few different ways to call methods. I’m still using 5.4.0f3 though, so I’m not sure how this compares to newer versions.
- Invoke a method with integer input, increase it and return the result
- Invoke a method with two referenced types and read from one of them and update the other with that value. Return a bool
- Invoke a method with a value type as input and return a struct value type from the input
Interestingly the struct method is slower than the referenced type. I was under the assumption it would push args to the stack and avoid the heap and making it faster.
The different implementations that can be seen in the profiler session:
This one would obviously be slower than any others. In addition it will engage the GC.
Using Func<> pointer
Uses an abstract class implementation
Simply uses a method from an interface
A simple class
Same as virtual method invoker but sealed
This is simple class reflected type and instantiated by Activation.
Methods are implemented in a static class
This is implemented manually inline since there is no inline keyword in c#
When profiling in the editor you can’t see much difference between the implementations, except for the reflection and inline method. So in order to test it you have to build it and attach the profiler. I went from 5000 iterations each update to 100 000 to get about the same execution time of 0.05ms in the inline case.
You can check out the project and test it yourself. I put it up on github.
Here are the graphs from my session.
* Input and output as ints
* Input and output as references
* Input and output as structs