6 ms·

I think the A7 being the first 6-wide core in the mobile space was far more important than the fact it was 64 bit. That gave it unprecedented single threaded pe

I think the A7 being the first 6-wide core in the mobile space was far more important than the fact it was 64 bit. That gave it unprecedented single threaded performance and competitors are struggling to keep pace on that front to this day, despite them also being 64 bit for several generations now.

cedivad 9y ago
Whats a 6-wide core?
- masklinn 9y ago
  Fetched & decoded instructions per cycle. Parent is wrong though, the A7 has 3-wide cores (and dual-core like previous chips)
  - servitor 9y ago
    The Cyclone core has 6 decoders. It can decode, rename and retire up to 6 instructions per cycle[1]. [1] https://www.anandtech.com/show/7910/apples-cyclone-microarchitecture-detailed https://www.anandtech.com/show/7910/apples-cyclone-microarch...
- ethbro 9y ago
  https://en.m.wikipedia.org/wiki/Superscalar_processor https://en.m.wikipedia.org/wiki/Superscalar_processor
simonh 9y ago
It's true that 64-bit wasn't as big a difference in terms of performance or user facing features, but it was an utter humiliation for the rest of the industry. Nobody could pretend that Apple was not way ahead of everyone else in terms of chip design capability and design sophistication. Right up to that point Samsung and Qualcom had been telling everyone they had all the experience and Apple was a newbie at this chip design stuff that didn't know what it was doing. All of a sudden they were faced with the reality. If they could do 64 bit a year before anyone else, they could do anything a year before anyone else. They could ship working products that other teams barely had on the drawing board, which means nobody could reasonably predict anything they could do next. How can you design a flagship phone for next year to compete with them, when you have no clue what features are even possible for them to have? That's what it brought to the table.
- tooltalk 9y ago
  why? Did Apple achieve something that was difficult or unexpected? IIRC, it was Apple who asked Samsung to collaborate with Intrinsity, most known for their FAST tech, to develop the Hummingbird core which was used in both Samsung and Apple's AP's. Only after having tested Intrinsity's tech, Apple acquired it -- so it's a bit stretch to agree with your narrative Samsung didn't see what was coming. Apple also took their time developing and releasing their own first AP about 4 years later. It also seems like while Apple is focusing on the single-core performance as their marketing point, Qualcomm and others are focusing on power-saving, having first implemented multi-core, then octo-cores on their chips. I'm not sure if that's a surprise or unexpected, since Apple's AP remained a single-core AP for a while. As for the 64bit, was there any compelling reason to go 64bit mobile? I remember when I used to work for wall street banks in the 1990's, the shortcomings of the 32bit arch limited our ability to scale and SUN's UltraSPARC which was widely used by in the industry came to relieve that problem.
  - xenadu02 9y ago
    64-bit ARM has similar advantages as 64-bit x86. It cleans up some cruft but more importantly it doubles the number of registers.
    - tooltalk 9y ago
      Sure, I get that. What I'm asking is if there were any technical challenges (even to this date) in mobile computing that necessitated a 64-bit mobile chip.
      - xenadu02 9y ago
        I guess it depends on your perspective. Is performance a technical challenge? IMHO I say yes. 64-bit enables a number of other things. It has a better ABI for argument passing. It allows more extensive use of tagged pointers (the ObjC runtime can fit many common 11-char or shorter strings in a single tagged pointer). It's also a chance to make any other ABI-breaking changes you want to make in the runtime. If you're forward looking you might say that mobile devices will exceed the 2GB/4GB limit soon enough so why not make the change now rather than waiting for it to become a problem? You'd get all the performance benefits listed above and a future-proof foundation on which to build.

cedivad 9y ago

Whats a 6-wide core?

masklinn 9y ago
Fetched & decoded instructions per cycle. Parent is wrong though, the A7 has 3-wide cores (and dual-core like previous chips)
- servitor 9y ago
  The Cyclone core has 6 decoders. It can decode, rename and retire up to 6 instructions per cycle[1]. [1] https://www.anandtech.com/show/7910/apples-cyclone-microarchitecture-detailed https://www.anandtech.com/show/7910/apples-cyclone-microarch...
ethbro 9y ago
https://en.m.wikipedia.org/wiki/Superscalar_processor https://en.m.wikipedia.org/wiki/Superscalar_processor

simonh 9y ago

It's true that 64-bit wasn't as big a difference in terms of performance or user facing features, but it was an utter humiliation for the rest of the industry. Nobody could pretend that Apple was not way ahead of everyone else in terms of chip design capability and design sophistication. Right up to that point Samsung and Qualcom had been telling everyone they had all the experience and Apple was a newbie at this chip design stuff that didn't know what it was doing. All of a sudden they were faced with the reality. If they could do 64 bit a year before anyone else, they could do anything a year before anyone else. They could ship working products that other teams barely had on the drawing board, which means nobody could reasonably predict anything they could do next. How can you design a flagship phone for next year to compete with them, when you have no clue what features are even possible for them to have? That's what it brought to the table.

tooltalk 9y ago
why? Did Apple achieve something that was difficult or unexpected? IIRC, it was Apple who asked Samsung to collaborate with Intrinsity, most known for their FAST tech, to develop the Hummingbird core which was used in both Samsung and Apple's AP's. Only after having tested Intrinsity's tech, Apple acquired it -- so it's a bit stretch to agree with your narrative Samsung didn't see what was coming. Apple also took their time developing and releasing their own first AP about 4 years later. It also seems like while Apple is focusing on the single-core performance as their marketing point, Qualcomm and others are focusing on power-saving, having first implemented multi-core, then octo-cores on their chips. I'm not sure if that's a surprise or unexpected, since Apple's AP remained a single-core AP for a while. As for the 64bit, was there any compelling reason to go 64bit mobile? I remember when I used to work for wall street banks in the 1990's, the shortcomings of the 32bit arch limited our ability to scale and SUN's UltraSPARC which was widely used by in the industry came to relieve that problem.
- xenadu02 9y ago
  64-bit ARM has similar advantages as 64-bit x86. It cleans up some cruft but more importantly it doubles the number of registers.
  - tooltalk 9y ago
    Sure, I get that. What I'm asking is if there were any technical challenges (even to this date) in mobile computing that necessitated a 64-bit mobile chip.
    - xenadu02 9y ago
      I guess it depends on your perspective. Is performance a technical challenge? IMHO I say yes. 64-bit enables a number of other things. It has a better ABI for argument passing. It allows more extensive use of tagged pointers (the ObjC runtime can fit many common 11-char or shorter strings in a single tagged pointer). It's also a chance to make any other ABI-breaking changes you want to make in the runtime. If you're forward looking you might say that mobile devices will exceed the 2GB/4GB limit soon enough so why not make the change now rather than waiting for it to become a problem? You'd get all the performance benefits listed above and a future-proof foundation on which to build.