The ARM64 advantage
Apple's announcement that the new iPhone 5s would sport the world's first, commercial 64-bit processor in a phone, the Apple A7, caused a ton of confusion that's still rippling through the internet. Somewhere between dismissal and deification lies the truth - does 64-bit really matter right now, and if so, for whom and how? Mike Ash adds to the answer:
Adding it all together, it's a pretty big win. My casual benchmarking indicates that basic object creation and destruction takes about 380ns on a 5S running in 32-bit mode, while it's only about 200ns when running in 64-bit mode. If any instance of the class has ever had a weak reference and an associated object set, the 32-bit time rises to about 480ns, while the 64-bit time remains around 200ns for any instances that were not themselves the target.
In short, the improvements to Apple's runtime make it so that object allocation in 64-bit mode costs only 40-50% of what it does in 32-bit mode. If your app creates and destroys a lot of objects, that's a big deal.
Yes, it's complicated. But that doesn't make it unimportant. If you want to know more, read the whole piece.
Have something to say about this story? Share your comments below! Need help with something else? Submit your question!