So I did some very quick tests with a few serialized core image
kernels within QC compositions, and set up a way to turn on/off
multithreaded GL.
Basically my pipeline consisted of
video input patch with its own QCRenderer.
|
QCImage Out
|
CMYK Halftone patch with its own QCRenderer
|
QCImage Out
|
Largish QC Patch with custom CIKernels with many queues etc with its
own QCRenderer
|
QCImage output
|
QC patch with Billboard display with its own QCRenderer
I did in fact see slightly poorer performance with MP openGL enabled
(assuming I did things correctly, which I believe I did), on the order
of 15%/20% less FPS on average. Im not 100% convinced yet, so ill keep
coming back to it as I add features. Should I find anything
interesting I will report it. Anyway.. sorry for the extraneous
traffic. Im curious why things get slower though, basic overhead of
keeping the thread state synchronized and not stepping on toes?
FYI this was the method I added to my app to enable/disable should
others want to test as well.
-(IBAction) enableMPGL:(id)sender
{
CGLError cglError = kCGLNoError;
// returns 0 or a 1 via NSButton toggle
if([sender state])
{
// Try and enable multithreaded openGL! WOooWW oWWWoo WEEE
WWooooow
cglError = CGLEnable( [v001GLContext CGLContextObj],
kCGLCEMPEngine);
if ( cglError != kCGLNoError )
{
// oops! not happening fuckers.
NSLog(@"Multithreaded OpenGL was not properly
enabled");
}
else
{
NSLog(@"Enabled Multhreaded OpenGL sucessfully");
}
}
else
{
cglError = CGLDisable([v001GLContext CGLContextObj],
kCGLCEMPEngine);
if ( cglError != kCGLNoError )
{
// oops! not happening fuckers.
NSLog(@"Multithreaded OpenGL was not properly
disabled");
}
else
{
NSLog(@"Disabled Multhreaded OpenGL sucessfully");
}
}
}
On Feb 19, 2008, at 4:28 PM, vade wrote:
I don't know of any appropriate cases where this would help
performance, but I've seen a few instances where it adversely
affected performance in a negative way (i.e. 60fps compositions
dropping to 20fps or worse). As with all optimization, be sure to
profile exhaustively to make sure what you're doing actually helps
rather than hinders.
Here's a quick doc I found that may help guide you:
http://developer.apple.com/technotes/tn2006/tn2085.html#TNTAG7
When/If you find where this option helps, please let me know; I'm
curious about where it's appropriate as well (in more concrete ways
than the doc outlines) :)
--
[ christopher wright ]
[EMAIL PROTECTED]
http://kineme.net/
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