Hi Greg,

On Jan 16, 2009, at 08:39, Greg Titus wrote:

The point of what people are trying to tell you is that the result you are getting (3ms per empty Objective-C call) is approximately 500,000 times longer than the time you ought to be getting (5-6ns). If an Objective-C message send took 3 milliseconds (333 method calls per second!), no useful software could ever have been written in the language.

Just a comment.. It's not every invocation of the empty method that takes 3ms, it's just happening often. What I'm concerned about, is the peak values, that makes chops in my rendering. I thought it was the fault of my rendering code, and it did take me some time to figure out that it wasn't *inside* my rendering, but *outside* it, that the time was spent.

From your guess at the end of your post, ("message dispatcher servicing") it is pretty clear that you don't really know what is going on.

:) I don't think any of us (except from Apple) knows what's exactly going on in there. ;)

Blaming the language environment for performance behavior that is vastly different than any of the rest of us have ever seen is not likely to be useful to you at all. There is something else happening with your application.

Uhm... Just to be stubborn: I changed the rendering to use plain C- routines, and now it doesn't get those high peak values anymore, and the chopping is gone. Yes, it's still an assumption, that this fixed it. I will try and see if it continues to work, but it definitely seems so much better right now.

We're just trying to save you the effort of rewriting and then discovering that nothing about the timing problem has changed, because you have misidentified the problem.

I know. -But I had to get rid of the chopping, and I couldn't find any other possibilities than to time my program.
Fortunately, it didn't take as long to rewrite, as I first expected.
I haven't noticed any lags of this kind before, which means that high peak impacts are probably not happening in general. -I just got shocked, when I saw the results. It could be because I'm not supposed to use ObjC-code in a CVDisplayLink callback function.


Good luck,

Thanks. :)


Love,
Jens

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