Photon mapping don't support hyperthreading

Fri, 28/05/2010 - 21:25 — tchap

Project:	YafaRay
Version:	0.1.2 Beta
Component:	Code
Category:	bug report
Priority:	normal
Assigned:	Unassigned
Status:	closed

I have a problem since the revision 541 and the "photon mapping" method.
My processor is a core i7 with 4 cores and hyper-threading.
When "auto-threads" is activated Yafaray chrashes

So, I have tested without "auto-thread" and with 1,2,3 or 4 cores, no problems. But when I use 5 or more cores, there is a crash.
I have look at the console and Yafaray chrashes when is written "point kdtree: Tree built"

There is no problem with other methods of lighting.
So the photon mapping seems to not support hyper-threading :?:

OS: Ubuntu 10.04 64bits (same problem with 9.10)
Blender 2.49b

Comments

Tue, 15/06/2010 - 17:55 — reny

#1

Hi,

I don't want to be rude, but it's a known fact among renderer developers that hyperthreading doesn't give much yield for optimize using them.

So everyone pretty much just concentrate on real cores/SMP sides of optimization.

I'm not a active developer yet, but just to let you know this feature doesn't worth using it.

But this is still a bug, as yafaray should fall back to available cores nicely and give warnings.

Cheers~

Ren

Wed, 14/07/2010 - 08:58 — MarcoA

#2

No problem here, with YafaRay-0.1.2-Beta-win32 on WinXP and Pentium 4 (1 core, Hyperthreading): "Auto-threads" corectly uses 2 threads; manually settings works without crash for whatever number of thread I use from 1 up to 20.

—

MarcoA
http://marcoalici.wordpress.com/

Mon, 29/08/2011 - 13:12 — Samo