Thread: When does a func() become too large?

You should use a profiler to find the bottlenecks when you've finished your program. It's the fastest and easiest way.

Don't forget most reliable.

Originally Posted by Elysia

You should use a profiler to find the bottlenecks when you've finished your program. It's the fastest and easiest way.

Forget my ignorance and do pray tell, what is this profiler in which you speak of?

A profiler is a system that tracks the execution of your program to find out where it spends its time.

A profiler is a piece of software that measures the amount of time, number of calls or similar that a particular piece of code is used.

There are two forms of profilers:
1. Sampling profiler - oprofile, vtune for example.
This method installs some extra code in certain interrupt(s) to capture where the code is executing when the interrupt is taken [and in modern processors also take advantage of "performance counters"], and can non-intrusively show pieces of code that are "heavy" on the CPU.
2. Intrusive profiler - gprof for example.
This method adds extra code to indicate which parts of the code is performed how many times. Obviously this is only necessary on basic blocks [that is, any code that has a jump to or from it, so loops and conditional code], so not every line of source code need instrumenting. But the additional code does change the behaviour of the code itself, and in small functions, it may double or triple the execution time - but you do get a very exact number of calls to the function, etc.

--
Mats

Also, under C++, the intrusive profilers typically need compiler support, while the sampling profilers don't. To use gprof, you need to compile and link your program with the -pg GCC option.

sounds cool, i'll give them a try.