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On Mac they have used the Grand Central Dispatch library since 2009. So if developers already used that, they were ready for M1 https://en.wikipedia.org/wiki/Gr

by xcv123 3y ago

On Mac they have used the Grand Central Dispatch library since 2009. So if developers already used that, they were ready for M1 https://en.wikipedia.org/wiki/Grand_Central_Dispatch https://en.wikipedia.org/wiki/Grand_Central_Dispatch

astrange 3y ago
GCD was actually not designed for this scenario and it's easy to mess up with it. It was designed for a large number of equal cores (aka SMP), meaning people did dispatch_async to the default concurrent queues all over the place, which is a bad pattern when you have to shrink down to phone size. Also, dispatch_semaphore has priority inversions and a lot of other features (like dispatch_group) are semaphores in disguise. It does work if you use it carefully, but Swift concurrency is a different design for a reason.
- xcv123 3y ago
  According to Apple developer documentation GCD is currently designed for this scenario https://developer.apple.com/documentation/apple-silicon/tuning-your-code-s-performance-for-apple-silicon#Execute-Tasks-Using-Grand-Central-Dispatch https://developer.apple.com/documentation/apple-silicon/tuni... "On a Mac with Apple silicon, GCD takes into account the differences in core types, distributing tasks to the appropriate core type to get the needed performance or efficiency."
  - astrange 3y ago
    It is now, but that's mostly from evolution in the iOS era. But like I said, it's not perfect.
  - krackers 3y ago
    that's probably assuming you set the qos correctly.
    - astrange 3y ago
      And dispatch_async loses QoS while dispatch_sync keeps it, but people often used to async unnecessarily.
      - krackers 3y ago
        >dispatch_async loses QoS Wait really? Where can I read more about this, this goes against what I would assume. Edit: Or do you mean that when dispatch_async the block is run with the QoS of target queue instead of source? That is what I would normally expect, if you want to "inherit priority" then dispatch_sync would do that, at the expense of blocking.

by xcv123 3y ago

astrange 3y ago

GCD was actually not designed for this scenario and it's easy to mess up with it. It was designed for a large number of equal cores (aka SMP), meaning people did dispatch_async to the default concurrent queues all over the place, which is a bad pattern when you have to shrink down to phone size. Also, dispatch_semaphore has priority inversions and a lot of other features (like dispatch_group) are semaphores in disguise. It does work if you use it carefully, but Swift concurrency is a different design for a reason.

xcv123 3y ago
According to Apple developer documentation GCD is currently designed for this scenario https://developer.apple.com/documentation/apple-silicon/tuning-your-code-s-performance-for-apple-silicon#Execute-Tasks-Using-Grand-Central-Dispatch https://developer.apple.com/documentation/apple-silicon/tuni... "On a Mac with Apple silicon, GCD takes into account the differences in core types, distributing tasks to the appropriate core type to get the needed performance or efficiency."
- astrange 3y ago
  It is now, but that's mostly from evolution in the iOS era. But like I said, it's not perfect.
- krackers 3y ago
  that's probably assuming you set the qos correctly.
  - astrange 3y ago
    And dispatch_async loses QoS while dispatch_sync keeps it, but people often used to async unnecessarily.
    - krackers 3y ago
      >dispatch_async loses QoS Wait really? Where can I read more about this, this goes against what I would assume. Edit: Or do you mean that when dispatch_async the block is run with the QoS of target queue instead of source? That is what I would normally expect, if you want to "inherit priority" then dispatch_sync would do that, at the expense of blocking.