Beginner's guide to graphical profiling

[matthewlai]

Only thing I would add is that leaving off optimization will drastically skew the results and lead you down the wrong path frequently. I've not found that optimization causes any profiling problems if you are simply looking at the top level (as you are) to see which procedures are the heavy-hitters. If you want to look inside a procedure to specific lines of code, optimization confuses things of course.

Yeah that would depend on the program. I found -Os to be a good compromise because it's almost as fast as -O3, but doesn't do function inlining (except for very tiny functions).

I guess I don't understand your "don't do other optimizations". -O anything (other than 0) is a massive optimization anyway and makes it impossible to profile at the source line level.

I included -Os in the command already, so I meant not to enable other optimizations beyond that.

[bob]

Only thing I would add is that leaving off optimization will drastically skew the results and lead you down the wrong path frequently. I've not found that optimization causes any profiling problems if you are simply looking at the top level (as you are) to see which procedures are the heavy-hitters. If you want to look inside a procedure to specific lines of code, optimization confuses things of course.

Yeah that would depend on the program. I found -Os to be a good compromise because it's almost as fast as -O3, but doesn't do function inlining (except for very tiny functions).

I guess I don't understand your "don't do other optimizations". -O anything (other than 0) is a massive optimization anyway and makes it impossible to profile at the source line level.

I included -Os in the command already, so I meant not to enable other optimizations beyond that.

That's the biggee, so what other optimizations would cause issues other than inlining?

[matthewlai]

Only thing I would add is that leaving off optimization will drastically skew the results and lead you down the wrong path frequently. I've not found that optimization causes any profiling problems if you are simply looking at the top level (as you are) to see which procedures are the heavy-hitters. If you want to look inside a procedure to specific lines of code, optimization confuses things of course.

Yeah that would depend on the program. I found -Os to be a good compromise because it's almost as fast as -O3, but doesn't do function inlining (except for very tiny functions).

I guess I don't understand your "don't do other optimizations". -O anything (other than 0) is a massive optimization anyway and makes it impossible to profile at the source line level.

I included -Os in the command already, so I meant not to enable other optimizations beyond that.

That's the biggee, so what other optimizations would cause issues other than inlining?

I don't think there's anything else.