msrw wrote:
My wife and I purchased two MBA M1 computers in early December, …
When we bought the new machines Apple advised us that the M1 chip uses memory in a more economical manner so additional ram memory would not be needed. If this is true, it’s odd that we’re getting the out of application memory message on the Airs when we never got that message on the Pros, even though both machines have 8gb of ram.
Here’s my question: is there some sort of glitch in how the OS is tracking or using ram that is something other than that the machine is actually maxing out ram?
…
I suspect there may well be «glitch[es] in how the OS is tracking or using ram that is something other than that the machine is actually maxing out ram».
In fact, I can just about guarantee it.
Since the Mac Operating System (OS) uses Virtual Memory (VM), the actual amount of Random Access Memory (RAM, or Dynamic RAM [DRAM]) is, actually, rather immaterial, except from a performance standpoint.
VM works by “swapping” memory between the RAM and your drive (Solid-State Drives [SSDs], in the case of the M1 Macs, and even most Intel based Macs).
In fact, for the last few macOS versions, it has even added a sort of intermediate case with Compressed memory (using the power of the CPU/GPU to compress and decompress memory—in a lossless manner—to use less space, for memory contents that aren’t being accessed quite so often as to make this impractical.
(Additionally, when the system does need to “swap” out memory contents, to make room for other parts of VM, it “swaps” out the Compressed portion. [It never “swaps” out code, since that never changes.])
This “swapping” uses part of your drive (a Volume named VM) as an extension of your RAM.
Since even SSDs are far slower than RAM (even more so for the M1’s, since their RAM can be accessed even faster than any off CPU RAM), the larger the “swap” space used, the slower your system will work, but it will, generally, still work, up to the point when the system is “swapping” so much that the system comes to a “crawl”. (That point is called “thrashing”.)
I’ve been using VM systems since the early ‘80s. I even owned (still own) a (‘90s) predecessor of the Mac OS X system (before Apple bought it, and introduced Mac OS X in 2001): even though it could only be upgraded to 8 MB (yes, a thousandth what the cheapest M1 Macs have), it didn’t have a performance issue until my “swap” space grew to over 100 MB. (Admittedly, memory and processors, then, were significantly slower than today. However, even though I never bought a Hard-Disk Drive [HDD] any slower than 7200 rpm, and SSDs are far faster, I wouldn’t expect the RAM to SSD speed ratio to be all that much worse, today.)
Additionally, as attested to, here, it’s not like the system was running out of “swap” space (the VM Volume can grow to the Available size on your SSD).
Furthermore, the one screenshot, here, demonstrates that the amount of “App Memory” was not “running out”.
Now. I have had a few instances where Big Sur 11.1, running on my Intel Mac mini (8 GB RAM) has complained of “running out of application memory”, but those were instances of a known process (Numbers) using a huge amount of VM.
I even had at least one case when the Application was Terminated, without being given the chance to choose what Apps to terminate!
However, even then, I appeared to have more Free space for VM (to say nothing of Available space).
I’ve even had times when my Memory Pressure was well into the Red, nearly at 100% (so, almost no “App Memory”), for an extended period of time, without getting the “running out of application memory” error.
(There are also some “oddities” about Memory values given in Activity Monitor, but who knows whether there’s any relationship, here.)
Unfortunately, none of this provide any immediate solutions!
