It is not a simple NVMe ssd Especially with M1 Macs. A Typical NVMe ssd will have its own controller, higher end SSD will also comes with a ssd Cache memory chip(ssd dram). Which in the newer Macs those don’t appear. A Mac CPU - M1 is taking the tasks where other ssd need the ssd Controller for the tasks , in fact The CPU cache and system RAM are build in one, including the Storage CACHE (SSD DRAM). I think we should call it Embedded onboard storage memory, just like in a phone, in a tv, We don’t say a phone “ssd” storage memory is SATA Or NVME interface.
Ok, I got that part, but TRIM should be just TRIM, a function to tell GC which cell can be cleared. This logic should hold true regardless where the storage controller and cache is. Isn’t that a reasonable guess?
It’s known that even the M1 is using normal NVMe (the raw storage part). Which means the write in process should be no different than any other NVMe. Which means, they need TRIM (in fact, MacOS also call it TRIM on M1 Mac. Therefore, it's reasonable to expect it use the same logic to free up empty cells like normal TRIM does) to keep the write in performance. Their own controller may be more aggressive to use TRIM, or the other way around. That algorithm may be very different than other SSD, but so far, no evidence to show that TRIM itself on M1 has any difference than on other system.
And for GC to work properly，free space is required. And when the NVMe is nearly full, the only avail free space for GC to work effectively should be coming from overprovisioning. Even Apple hide many technical stuff, but this kind of basic stuff for non SLC solid state storage should be still true.
Of course, you can say this is BS. It's your opinion, I respect that. It's your freedom to think that way and express it accordingly. You are right that I don't know the details which Apple never disclose. But I think we can still have logical surmise base on what we know.
