IMO, that's likely to be a much bigger factor than the filesystem.
https://www.anandtech.com/show/9136/the-2015-macbook-review/...
They are going to need to support and perform well on non-SSD systems for quite a while.
> Is APFS open source?
> An open source implementation is not available at this time. Apple plans to document and publish the APFS volume format specification.
Source: https://developer.apple.com/library/archive/documentation/Fi...
My theory is that Apple rushed APFS and its implementation isn't in a great shape for the public review. APFS doesn't feel any faster on my SSDs on macOS. I suspect they'll add it in a few years, after a few iterations.
The rollout of APFS was _incredibly_ well done; I don't think there is even a remote comparison to how successful it was. A new file system was rolled out to millions of devices in an automated fashion with very few issues. I don't think anyone else has even considered such a thing. I highly doubt the code is that rough, I can't imagine pulling this off without fairly solid core code in place.
Perhaps it’s just the lawyer reviews holding it up.
> > Is APFS open source?
> > An open source implementation is not available at this time. Apple plans to document and publish the APFS volume format specification.
They claim to plan to document it fully later.
(Yes, I know about the anti-RE clauses in EULAs. If they were actually enforced as strictly as they claim, people like Mark Russinovich and Matt Pietrek would've been sued out of existence long ago, along with just about every Windows security researcher.)
There're def a ton of other possibilities. Some locking could be overbroad, like an exclusive lock where a reader lock would be enough. I don't see super-strong evidence that any locks involved are actually global, just that they're under contention here. And I can understand shipping a product with somewhat excessive locking because perf issues with specific workloads are a better problem to have with your shiny new FS rollout than data loss.
Anyway it's mostly shooting in the dark for us here (though cool some folks disassembled the functions), but there are some shots in the dark that look different from what I could find in the comments already here :)
