in computers, what do “wired memory”, “compressed memory” and “Swap” mean? Why is it bad that a computer is using a lot of Swap?
In: Technology
“Compressed memory” is… Memory areas whose contents have been compressed to save some space in RAM.
“Swap” is memory areas that are knocked out of ram and written to the hard drive/SSD when the computer is running out of space in RAM. Think of it like putting something on the table to free up a hand. Reading them back into RAM when there is need for them again takes 30-100x as long as if they were in RAM, so if a lot of your memory is swapped out because you ran out of RAM your PC slows down to “granny’s email rig” tier.
Wired memory is stuff that must never get put on swap. It’s OS internal stuff and such.
> ELI5: in computers, what do “wired memory”
That’s an OSX specific term for memory which can’t be swapped out. So pretty much memory that’s taken no matter what, for various technical reasons.
> “compressed memory”
It’s kind of an intermediate kind of swap. Rather than writing out something rarely used to disk, it’s compressed and kept in RAM. This is faster than writing it to disk, because disks are slow, even SSDs.
> and “Swap” mean?
Stuff that used to be in RAM, and was now written to disk because it wasn’t needed much. This is things like those browser tabs you’ve opened 3 hours ago and not looked since.
> Why is it bad that a computer is using a lot of Swap?
Mostly because it’s a sign you don’t have enough RAM, and having to use the disk to compensate by moving out the rarely used bits. But disk is very slow compared to RAM, so using a large amount of swap risks everything grinding to a halt.
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