64 bit is slow!!!

ZeroPoint
Posts: 8
Joined: Sat Nov 02, 2013 6:47 pm

64 bit is slow!!!

Post by ZeroPoint »

I'm new to Bullet Physics and C++ but managed to make a physics demo where you can knock down tall stacks of boxes. I'm using CodeBlocks with Mingw c++ compiler on Windows 7 64bit. I first made the Bullet Physics libraries and the demo using 64bit Mingw c++. I switched to 32bit Mingw C++ compiler and it is much faster. Anyone else have this issue with 64bit vs 32bit performance?
Basroil
Posts: 463
Joined: Fri Nov 30, 2012 4:50 am

Re: 64 bit is slow!!!

Post by Basroil »

Are you sure you have the proper optimizations being done on x64 builds? Namely SIMD optimizations that are sometimes not properly accessed on different compilers and just skipped over.
ZeroPoint
Posts: 8
Joined: Sat Nov 02, 2013 6:47 pm

Re: 64 bit is slow!!!

Post by ZeroPoint »

Basroil wrote:Are you sure you have the proper optimizations being done on x64 builds? Namely SIMD optimizations that are sometimes not properly accessed on different compilers and just skipped over.
Well, this time around I selected the x64 compiler flags and tried to rebuild the libraries. Now I'm getting an "internal compiler error: segmentation fault"

C:\bullet-2.81-rev2613\src\BulletCollision\CollisionDispatch\btInternalEdgeUtility.cpp:310:2: internal compiler error: Segmentation fault
aash29
Posts: 8
Joined: Wed May 09, 2007 9:06 am

Re: 64 bit is slow!!!

Post by aash29 »

I can confirm that x64 build is noticeably slower. Which flags are you talking about?
ZeroPoint
Posts: 8
Joined: Sat Nov 02, 2013 6:47 pm

Re: 64 bit is slow!!!

Post by ZeroPoint »

aash29 wrote:I can confirm that x64 build is noticeably slower. Which flags are you talking about?
I'm using CodeBlocks IDE so on the menu bar I select "Settings", then "Compiler". Then select the second tab and there's a long list of checkboxes where you can select how you want your code optimized and also includes a list of CPU's you can select. There's four checkboxes for different 64bit processors you can select. I'm just wondering if Bullet Physics was just developed for 32bit.
dern23
Posts: 26
Joined: Thu Oct 04, 2012 1:58 pm

Re: 64 bit is slow!!!

Post by dern23 »

That's odd, I just tested the Basic demo compiled with VS2010; x64 was slightly faster for me.