Comments on: Exceptions and various compilation option speeds

By: Rene Dudfield

Rene Dudfield — Fri, 08 Jan 2010 13:22:04 +0000

ah ok. Maybe it only makes a difference if you have a lot of classes defined. The main benefit of fno-rtti is supposed to be less memory usage.

That’s VERY cool to get within that close of C

By: philhassey

philhassey — Thu, 07 Jan 2010 21:10:44 +0000

A pure-C implementation does 75ms vs. 115ms. Which seems pretty close considering the extra hoops tinypyC++ does to get in ref counting and other syntax niceties.

By: philhassey

philhassey — Thu, 07 Jan 2010 20:58:26 +0000

-fno-rtti and -ffast-math didn’t see to make a discernible difference.

I should do a comparison to a pure-C implementation, but I don’t really expect to be able to make it much faster than it is.

By: Rene Dudfield

Rene Dudfield — Thu, 07 Jan 2010 17:33:53 +0000

hey ya,

Another speed up used to be disabling rtti with -fno-rtti Also try -ffast-math if you’re not using it already.

I guess one conclusion from your results could be memory management is important for speed. Since removing that one ‘new’ gave the best speedup. Removing allocations at run time often gives nice speedups

cya.

By: philhassey

philhassey — Thu, 07 Jan 2010 16:41:55 +0000

A few of us chatted about this in #LD yesterday, and I tried a few more things, some of my observations there could just be ’rounding’ errors, actually.

But the bottom line is, removing exceptions gives real gains when you compile with -O3. ~20% gain is the average of the two cases.

By: Sol_HSA

Sol_HSA — Thu, 07 Jan 2010 11:42:02 +0000

I don’t quite follow your conclusions.. based on your data, dropping the exceptions speeds things up. Or are you referring to the speed of the debug builds? Who cares? =)