[IronPython] Optimized methods and serious performance issues

[Jonathan Jacobs]

(Please disregard any earlier message about this, I think I might have pressed 
"Send" accidentally.)

Hi,

I ran across some "interesting" behaviour today.

Short version:
I have a handful of Direct3D.Mesh objects (courtesy of Direct3D.Mesh.Teapot) 
which I render using self.meshInstance.DrawSubset(0). I've been experiencing 
pretty serious performance issues, so I did a bit of testing and this is what 
I came up with:

(The averages are accumulated every call and averaged (and output) every 500 
calls, a small value is obviously better, all values are in milliseconds.)

No drawing calls:
running average: 0.0236448413598 ms
running average: 0.0229452898402 ms
running average: 0.0236400825059 ms
running average: 0.0257713352135 ms

No drawing calls, -X:NoOptimize:
running average: 0.0251883756139
running average: 0.0250299057799
running average: 0.0224732115359
running average: 0.0225412631463

self.mesh.DrawSubset(0):
running average: 3.40948918622 ms
running average: 3.45289207504 ms
running average: 3.43480367147 ms
running average: 3.45502784866 ms

self.mesh.DrawSubset(0), -X:NoOptimize:
running average: 0.111673644441 ms
running average: 0.118880928633 ms
running average: 0.134856876975 ms
running average: 0.11670232533 ms

Helper.DrawMesh(self.mesh, 0):
running average: 0.0415348007294 ms
running average: 0.0328241945979 ms
running average: 0.0296612223703 ms
running average: 0.0330559507815 ms

Helper.DrawMesh(self.mesh, 0), -X:NoOptimize:
running average: 0.063753413583 ms
running average: 0.0668509515698 ms
running average: 0.0603922350916 ms
running average: 0.070181197511 ms

Helper.DrawMesh is my own function implemented in C#:
public class Helper {
   public static void DrawMesh(Microsoft.DirectX.Direct3D.Mesh mesh, int id) {
     mesh.DrawSubset(id);
   }
}

I'm interested as to why the self.mesh.DrawSubset call is so disappointingly 
slow and why it is sped up by *disabling* method optimization.

Unfortunately, it is laborious for me to separate the useful code from the 
not-so-useful code and I'm not sure how to reproduce this outside of DirectX. 
I can take some time out to try and cut this down to the bare essentials if 
need be.

Regards
-- 
Jonathan

When you meet a master swordsman,
show him your sword.
When you meet a man who is not a poet,
do not show him your poem.
                 -- Rinzai, ninth century Zen master