From: David Masover <ninja@...>
Date: 2009-03-10T17:33:04+09:00
Subject: Re: Ruby OpenGL Gears example that uses shiny and velvet GLSL shaders

Matthias Reitinger wrote:
> Michael Brooks wrote:
>   
>> On another topic, what kind of performance / fps are you getting?  My
>> past experience has been that Nvidia has better OpenGL drivers than ATI.
>>     
>
> reima@marvin:/tmp$ ruby gears_using_shaders.rb
> 14146 frames in  5.000 seconds = 2829.200 FPS
>   

My results were frighteningly worse, at first:

dave@SERENITY ~/tmp> uname -a
Linux serenity 2.6.27-11-generic #1 SMP Thu Jan 29 19:28:32 UTC 2009 
x86_64 
GNU/Linux                                                                           

dave@SERENITY ~/tmp> 18 ruby -v
ruby 1.8.7 (2008-08-11 patchlevel 72) [x86_64-linux]
dave@SERENITY ~/tmp> 19 ruby -v                    
ruby 1.9.1p0 (2009-01-30 revision 21907) [x86_64-linux]
dave@SERENITY ~/tmp> head -n 12 /proc/cpuinfo         
processor       : 0                                   
vendor_id       : GenuineIntel                        
cpu family      : 6                                   
model           : 23                                  
model name      : Intel(R) Core(TM)2 Duo CPU     T9300  @ 2.50GHz
stepping        : 6                                             
cpu MHz         : 800.000                                       
cache size      : 6144 KB                                       
physical id     : 0                                             
siblings        : 2                                             
core id         : 0                                             
cpu cores       : 2                                             
dave@SERENITY ~/tmp> lspci | grep VGA
01:00.0 VGA compatible controller: nVidia Corporation GeForce 8600M GT 
(rev a1)
dave@SERENITY ~/tmp> 18 ruby -rubygems gears_using_shaders.rb
9232 frames in  5.022 seconds = 1838.311 FPS                   
9982 frames in  5.000 seconds = 1996.400 FPS                   
9962 frames in  5.000 seconds = 1992.400 FPS                   
9923 frames in  5.000 seconds = 1984.600 FPS                   
9981 frames in  5.000 seconds = 1996.200 FPS                   
dave@SERENITY ~/tmp> 19 ruby gears_using_shaders.rb
9261 frames in  5.000 seconds = 1852.200 FPS
9835 frames in  5.000 seconds = 1967.000 FPS
9880 frames in  5.000 seconds = 1976.000 FPS
9901 frames in  5.000 seconds = 1980.200 FPS
9906 frames in  5.000 seconds = 1981.200 FPS
dave@SERENITY ~/tmp> glxgears
11864 frames in 5.0 seconds = 2372.706 FPS
12272 frames in 5.0 seconds = 2453.951 FPS
12457 frames in 5.0 seconds = 2491.129 FPS
11393 frames in 5.0 seconds = 2278.451 FPS
11255 frames in 5.0 seconds = 2246.413 FPS

Then I remembered I'm running KDE4, with all kinds of effects turned on. 
Quickly toggling them off reveals:

dave@SERENITY ~/tmp> 18 ruby -rubygems gears_using_shaders.rb
21374 frames in  5.000 seconds = 4274.800 FPS
21964 frames in  5.000 seconds = 4392.800 FPS
22223 frames in  5.005 seconds = 4440.160 FPS
21960 frames in  5.000 seconds = 4392.000 FPS
22011 frames in  5.002 seconds = 4400.440 FPS
dave@SERENITY ~/tmp> 19 ruby gears_using_shaders.rb
20571 frames in  5.000 seconds = 4114.200 FPS
21922 frames in  5.000 seconds = 4384.400 FPS
22217 frames in  5.000 seconds = 4443.400 FPS
22022 frames in  5.000 seconds = 4404.400 FPS
21693 frames in  5.000 seconds = 4338.600 FPS
dave@SERENITY ~/tmp> glxgears
26268 frames in 5.0 seconds = 5253.481 FPS
27987 frames in 5.0 seconds = 5597.365 FPS
27844 frames in 5.0 seconds = 5568.736 FPS
28008 frames in 5.0 seconds = 5601.509 FPS
28031 frames in 5.0 seconds = 5600.459 FPS

Looks like it is GPU-bound -- no real difference between Ruby 1.8.7 and 
1.9.1, but a huge difference between compositing and no compositing. For 
those with KDE4, the default keystroke to toggle desktop effects is 
shift+alt+f12. Can't live with 'em, can't live without 'em.