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> I'm disappointed even though it's entirely predictable that VisionOS is built on the iOS/iPadOS foundation rather than OSX. They’re the same foundation, iOS

> I'm disappointed even though it's entirely predictable that VisionOS is built on the iOS/iPadOS foundation rather than OSX. They’re the same foundation, iOS is a fork of OS X and was originally announced as such. I’d be shocked if there isn’t a well maintained internal build of iOS which keeps parity with macOS windowing etc. The difference in restrictions between the platforms is entirely arbitrary. If this device appeals to Mac users or would-be Mac users, I’d be shocked if it doesn’t at least eventually allow a Mac-like environment.

astrange 3y ago
It certainly isn't arbitrary, macOS has swap and doesn't kill apps and iOS doesn't have swap and does kill apps. This makes everything very different, and one makes it easier to do real-time rendering than the other.
- eyelidlessness 3y ago
  I guess I should clarify. It’s arbitrary in that the restrictions are policy-based, not limitations of the underlying technology. There’s no technical reason iOS couldn’t have swap, it’s not available because trade off decisions were made to enable use cases on much more limited devices.
- MBCook 3y ago
  The recent iPads based on M series chips now support swap. I think it was added in iPadOS 16 last year.
  - astrange 3y ago
    It's different-ish. iPadOS is still a more limited/controlled OS and the swap policy is also more limited. You can see it in the open source kernel where it's called "app swap", so it doesn't swap out the OS, but on macOS it can. "Limited" makes it, well, limited, but it has performance advantages: fewer unexpected page faults mean audio/video processes won't unexpectedly drop a frame as often, and there's fewer disk writes which is good for the lifespan of the hardware it runs on. Btw iOS actually has a very limited swap policy called "freezer" that only applies to suspended background apps, and only when it's in the performance budget.
    - zaptrem 3y ago
      Where can I read more about this?
      - astrange 3y ago
        The xnu source code on github. The rest of it… well you just did read about it. There's an older book called Mac OS X Internals that covers some of it.

astrange 3y ago

It certainly isn't arbitrary, macOS has swap and doesn't kill apps and iOS doesn't have swap and does kill apps. This makes everything very different, and one makes it easier to do real-time rendering than the other.

eyelidlessness 3y ago
I guess I should clarify. It’s arbitrary in that the restrictions are policy-based, not limitations of the underlying technology. There’s no technical reason iOS couldn’t have swap, it’s not available because trade off decisions were made to enable use cases on much more limited devices.
MBCook 3y ago
The recent iPads based on M series chips now support swap. I think it was added in iPadOS 16 last year.
- astrange 3y ago
  It's different-ish. iPadOS is still a more limited/controlled OS and the swap policy is also more limited. You can see it in the open source kernel where it's called "app swap", so it doesn't swap out the OS, but on macOS it can. "Limited" makes it, well, limited, but it has performance advantages: fewer unexpected page faults mean audio/video processes won't unexpectedly drop a frame as often, and there's fewer disk writes which is good for the lifespan of the hardware it runs on. Btw iOS actually has a very limited swap policy called "freezer" that only applies to suspended background apps, and only when it's in the performance budget.
  - zaptrem 3y ago
    Where can I read more about this?
    - astrange 3y ago
      The xnu source code on github. The rest of it… well you just did read about it. There's an older book called Mac OS X Internals that covers some of it.