Good takes and bad takes on Apple Silicon
There are a lot of people out there that seem to be clinging to some weird ideas about what the Apple Silicon transition is going to look like, and what the Apple Silicon team “can do”, in terms of what they can deliver.
First, someone who seems to “get it” pretty well, Rene Ritchie. Here are two of his very clear and informative videos about why “Apple Silicon” is not just “ARM”, and what that means for the Mac going forward:
Rene Richie on YouTube:
The key takeaway here is that many of the huge advantages that Apple Silicon will bring to the Mac come from everything else that Apple will integrate into the chips, not just from using their own CPU cores. Having said that, I think there’s a lot of confusion about the likely performance of those cores. More on that below.
I’m not going to link to blog posts, tweets, and YouTube videos of the bad takes, for two reasons. Primarily, because bagging on people who are coming at this from a position of ignorance seems kind of mean. But also, because there are so many bad takes for each of these positions, there’s no point in singling out any particular instance of them. Having said that, here are some bits of commonly “known facts” about Apple Silicon that I think are really wrong-headed, and why I think so.
Claim: ARM Macs will never be as fast as Intel Macs
You see a bunch of variations on this, from “obviously, the ARM processors will be for the low-end, but they’ll continue to use Intel for the Mac Pro and the MacBook Pro”, to “Obviously, the low-end Macs will transition first, and we won’t see ‘pro’ Macs until late next year, at the earliest”.
My take: You will see ‘Pro’ Apple Silicon Macs this year
Apple’s flagship product is the MacBook Pro. It’s the product that everybody wants, and also the one that a lot of people buy, especially “Pro Users”, whatever that name might mean. Apple will definitely not carve out solely the low end of the Mac range for their new Apple Silicon processors, because the perception of “Apple Silicon means low-end” is not something they want to have stick to the new product line.
In addition, based on what we know, and can extrapolate from, the first Apple Silicon processors are likely going to be substantially faster than the Intel processors in the existing laptop range. In single-core performance, the A12Z is already on par with the Intel processors in the MBP line. It’s really hard to say what the performance improvement will be from the A12Z to the first Apple Silicon Mac chip, but my best guess is somewhere between 50% and 100% improvement over the A12Z. At that speed, those Apple Silicon chips will just wipe the floor with the current Intel processor MacBook Pros in single-core speed. Beyond that, it’s mostly a question of how many “performance” cores go into that processor.
Claim: ARM Macs will not support discrete GPUs
This is apparently based on a single slide from a single WWDC 2020 presentation: Bring your Metal app to Apple Silicon Macs. Based on seeing “Intel, Nvidia, and AMD GPUs” under the Intel-based Mac heading on one side of the slide, and “Apple GPU” on the other side, under Apple Silicon, some people have apparently concluded that discrete GPU support is not going to be available on Apple Silicon.
My Take: We really don’t know, but it seems unlikely that discrete GPUs will never be supported
The point of the presentation at WWDC was very much not “we won’t support discrete GPUs on Apple Silicon”. The point of the presentation was “you definitely don’t want to assume that ‘integrated equals slow’, when dealing with Apple Silicon”. It’s likely that Apple will still have discrete GPU options on some of their Pro devices.
However, I would not be at all surprised if the first few Macs released didn’t have discrete GPUs, because the integrated GPU will have better performance than the top laptop GPUs currently available. We do know that Apple Silicon Macs will have Thunderbolt and PCIe, so they will have the hardware capability to support discrete GPU configurations, including external GPUs. It’s just a question of drivers, at that point. Apple will either write the needed drivers, or pay the GPU vendor to write them, if they’re needed to achieve a particular performance level.
Claim: Much existing software will not come to Apple Silicon Macs soon, or indeed at all
This is often tied to the argument that “x86 processors are just better for ‘heavy processing’ than ARM, which are optimized for power efficiency”. Given that assumption, they then say you won’t see Photoshop, or Logic, or Premiere, or whatever other piece of software on ARM Macs, because they won’t be fast enough. A different argument is that the effort of porting will be too high, and so third-party developers will not bother porting to the Apple Silicon architecture.
My Take: Building for Apple Silicon is pretty darn easy, and Rosetta2 is better than you think
I talked about this in a previous post, but this transition is going to be much less painful for most developers than the PPC->Intel transition was, or in fact than the transition from x86-32bit to x86-64, which a bunch of developers just went through for Catalina. If an app runs on Catalina, it’ll run on Apple Silicon, eventually.
I need to be careful about what I say in this next section, because I do have the Apple DTK, and it came with a fairly restrictive NDA, saying not to talk about performance or benchmark results. But I have run a bunch of third-party software under Rosetta2, and other than a compatibility issue related to page size that’s described in the DTK release notes (you may not be able to read that, without a developer account), almost everything I’ve tried runs perfectly well. It’s actually hard to tell the difference between running under Rosetta, and running something native. It does use more CPU power to run a Rosetta process than a native process, and they’re slow to start the very first time, but other than that, it’s completely seamless.
Someone posted Geekbench scores from a DTK, with Geekbench running under Rosetta, and the performance is 20-30% slower than native (as compared to the iPad Pro running the iOS version natively). Assuming that holds generally, and that the Apple Silicon Mac processors will be substantially faster than the existing Intel Mac processors, I wouldn’t be too surprised if for many users, running their existing software under Rosetta would still be a performance improvement over their current Mac. Once native versions of these apps become available, there will be no contest.
Claim: The Surface Pro shows that ARM isn’t ready for the desktop
The Surface Pro is an obvious comparison to make, because it’s an “ARM laptop”, running an ARM version of Windows. They’re great, for what they are. But they haven’t been a great success. The lack of software support, and disappointing performance when emulating x86 code, has been used to justify skepticism of the viability of Apple Silicon Macs.
My Take: The Surface Pro is a great example of the key differences between Apple and Microsoft.
From a third-party developer’s perspective ARM Windows is this weird off-shoot of the main Windows product line. Even if you want to support it, it’s a much smaller market than the x86 mainstream Windows family, and so the payoff for the porting work is uncertain. When Apple switches to Apple Silicon, they will completely switch over. At the end of the two year transition, every new Mac will be running on Apple Silicon. If you want to be in the Mac software market, you will need to support Apple Silicon.
It turns out that there is hardware support for Total Store Ordering, or TSO, built in to Apple Silicon processors. This was somehow discovered by a third party, and they’ve subsequently released a proof-of-concept for enabling TSO on a per-thread basis on the DTK. The relevance here is that TSO is one of the major differences between the memory model of Intel processors and ARM processors. By providing this switch, Apple have eliminated a huge source of synchronization slowdowns (and potentially bugs) when translating x86 code to ARM code in Rosetta. This is a hardware feature implemented just to support a particular piece of software, and a great illustration of the advantages Apple gets from controlling the entire stack from hardware to applications.
Claim: Geekbench is not a realistic benchmark, and doesn’t reflect real-world performance
This is a fun one. Since Geekbench shows the A12Z as being on par with current Intel laptop chips, it must be that the benchmark is wrong, or intentionally skewed in Apple’s favor.
My Take: Benchmarking is hard, but Geekbench is at least trying to be fair
You can see descriptions of the Geekbench micro-benchmarks here and here. There’s nothing in here that would obviously bias these tests towards or away from any particular processor. They’re artificial benchmarks, but are built up of things that real applications actually do – image compression, database operations, etc, etc.
The first round of Apple Silicon Macs are going to be setting the conversation for the next year about the wisdom of Apple’s rather risky decision to abandon Intel. Apple obviously knows this, and I would not be at all surprised if the first Apple Silicon MacBook Pro (or whatever they call the pro laptop, if they rename it) will be the fastest Mac laptop yet. And the desktop Macs will also be an impressive upgrade over their current counterparts.