The ARM64 advantage

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.

Source: Mike Ash via Daring Fireball

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Rene Ritchie

EiC of iMore, EP of Mobile Nations, Apple analyst, co-host of Debug, Iterate, Vector, Review, and MacBreak Weekly podcasts. Cook, grappler, photon wrangler. Follow him on Twitter and Google+.

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Reader comments

The ARM64 advantage


The advantage may not be apparent right now; but it surely makes the 5s a lot more future proof. Future iOS versions and apps will really step up and make the best use of 64 bit architechure. Maybe it will handle iOS 9 a lot better than how 4s handles iOS 7.

Much as I agree with your sentiment. I can't imagine the 4S has problems with iOS7, I have a 4 that seems to run it just fine.

Your among the lucky ones. My iphone 4 has become annoyingly slow. High quality youtube videos (in safari) stutter, call logs take a few seconds to update and so on, tabs in safari auto-reload all the time.

I can understand that I suppose as everyone will be slightly different. Still, assuming they have some in stock I'll have a 5S tomorrow.