Re: [hatari-devel] OS X performance problem

[Eero Tamminen <oak@xxxxxxxxxxxxxx>]

Hi,

On torstai 29 toukokuu 2014, Anders Eriksson wrote:
> this was a topic several years ago. The status display can slow framerate
> down to a halt by just blinking the drive led on/off. It's not a new
> problem, but might be intensified with more stuff in the statusbar.
> 
> Funnily enough, I notice this problem much more with the powerful
> discrete AMD Radeon videochip rather than with the slower Intel
> videochip.

This kind of trivial blitting operation is memory bandwidth bound,
not 3D operations bound.  OSX SDL backend apparently does separate
texture upload for each rect update. With the discrete graphics card
the data goes over PCI Express bus, with integrated GPU through
system memory bus.

On Intel Ivy Bridge and Haswell desktops, the theoretical memory
bandwidth (if you have at least two 1600Mhz DDR3s) is 25 GB/s,
see for example [1]:
	http://ark.intel.com/products/80815

And 16-lane PCI-E v3 memory speed is 16 GB/s:
	http://en.wikipedia.org/wiki/PCI_Express

What PCI-E connection you have to your card, and what Intel processor?


	- Eero

[1] Wikipedia has nice links to Intel site for different CPUs:
http://en.wikipedia.org/wiki/Haswell_%28microarchitecture%29#Desktop_processors