Metal on macOS – Monitor refresh sync?

Question

I am in the process of converting some old OpenGL code to Metal.

At the moment I am using a MTKView to render a memory buffer to a window. I'm using it with paused = YES, enableSetNeedsDisplay = NO, and manual calls to draw() from my rendering loop.

Everything appears to be working, except for the fact that I am limited to 60 frames per second for no obvious reason. I suspect that Metal is synchronising to the monitor refresh when I don't want it to.

When I resize the window my frame rate temporarily jumps to 150+ frames per second, which tells me that the limit is not of my making.

Does anyone know how to stop this frame rate limit? I have tried setting preferredFramesPerSecond to different values (both lower and higher) but this seems to have no effect.

Thanks in advance for any pointers.

Answer 1

Typically enough I figured it out a few minutes after asking the question:

CAMetalLayer *c = self.layer;
c.displaySyncEnabled = NO;