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Thanks for the info! I'm no Vulkan expert. I'm coming from OpenGL, hoping that Vulkan will make things better eg at allowing the app to manage GPU memory explic

Thanks for the info! I'm no Vulkan expert. I'm coming from OpenGL, hoping that Vulkan will make things better eg at allowing the app to manage GPU memory explicitly to suit the application use-case. Agreed, reliable was the wrong word. Depending on the use-case, the ability for a program to tune its memory usage to effect performance in some beneficial way can mean the difference between a program that is usable or not - for an application trying to extract max perf. It is my understanding that Vulkan will help with this. Can you confirm?

nhaehnle 9y ago
I'm honestly uncertain. My best guess right now is: If you know what you're doing, it's possible that you might do memory management better in Vulkan. Then again, it's possible that by trying to exploit the freedom Vulkan gives you, you're actually making things worse. I suspect it's similar to prefetching and non-temporal moves on the CPU in that way. If you're targeting a specific machine and spend a lot of time on optimizations, then using those advanced features can give you a performance boost. But then a new machine comes along, and your fancy tweaks turn out to have made thing worse -- this happened with some games when Ryzen came out, and I suspect it's likely to happen with Vulkan as well. The main benefit of Vulkan is that it cuts CPU overhead because the driver no longer has to do state tracking. The state tracking is done (almost) entirely by the game engine, which knows precisely what is needed and can therefore do the job more efficiently. This is totally unrelated to memory management. Though keep in mind I'm speaking from a Linux perspective. On Windows, video memory is managed somewhat differently at least in WDDM2. Still, I'd be surprised if the story is much different. Vulkan doesn't expose the details of video memory swapping.
- laythea 9y ago
  Thanks again.

nhaehnle 9y ago

I'm honestly uncertain. My best guess right now is: If you know what you're doing, it's possible that you might do memory management better in Vulkan. Then again, it's possible that by trying to exploit the freedom Vulkan gives you, you're actually making things worse. I suspect it's similar to prefetching and non-temporal moves on the CPU in that way. If you're targeting a specific machine and spend a lot of time on optimizations, then using those advanced features can give you a performance boost. But then a new machine comes along, and your fancy tweaks turn out to have made thing worse -- this happened with some games when Ryzen came out, and I suspect it's likely to happen with Vulkan as well. The main benefit of Vulkan is that it cuts CPU overhead because the driver no longer has to do state tracking. The state tracking is done (almost) entirely by the game engine, which knows precisely what is needed and can therefore do the job more efficiently. This is totally unrelated to memory management. Though keep in mind I'm speaking from a Linux perspective. On Windows, video memory is managed somewhat differently at least in WDDM2. Still, I'd be surprised if the story is much different. Vulkan doesn't expose the details of video memory swapping.

laythea 9y ago
Thanks again.