> All of those tasks can be done with decent single-threaded performance, but lots of those tasks also benefit from multithreading
Most of those tasks benefit from multiple processors. Multithreading is less clear-cut because you're trading the win for under-optimized code against increased pressure on shared resources (which is one of the reasons why it's opened some windows for security attacks). It's not hard to find pro workloads which perform better without multithreading enabled and considering that Apple will own the entire stack up to some of the most demanding apps they're well positioned to have both solid data on the tradeoffs and architectural changes.
Note for the downvoters who might confused: I’m using multithreading in hardware sense of symmetric multithreading (SMT), which Intel refers to as HyperThreading:
Hyper threading is indeed meant for languages like Python or Javascript that use pointers everywhere. Once you have an optimized workload with little pointer chasing the only other meaningful benefit of SMT come from the fact that you can run floating point workloads alongside integer workloads. That's a pretty rare situation but it does happen sometimes.
That was basically my thought: there are plenty of programs which it can help (almost all business apps) but not all of those are limiting anyone’s work and the feature isn’t free. Having multiple true cores has been common for multiple decades now and I’d be really curious whether a modern chip design team would feel it’s worth investing in if they didn’t already have it. My understanding is that SMT has a power cost comparable to extra cores and given how well Apple’s CPU team has been executing I’d assume there’s been careful analysis behind not implementing it yet.
Most of those tasks benefit from multiple processors. Multithreading is less clear-cut because you're trading the win for under-optimized code against increased pressure on shared resources (which is one of the reasons why it's opened some windows for security attacks). It's not hard to find pro workloads which perform better without multithreading enabled and considering that Apple will own the entire stack up to some of the most demanding apps they're well positioned to have both solid data on the tradeoffs and architectural changes.