M1 Mac SSD Swapping

#1

Post by sslalready » Sat, Feb 13, 2021, 11:35 PM UTC

Re: M1 Mac SSD Swapping

#2

Post by spideymans » Sun, Feb 14, 2021, 12:09 AM UTC

Even on the 16 GB model, the system very aggressively swaps. During my normal workflow, RAM usage is typically at 12 GB, with 4 GB free and 4 GB+ swapped to the SSD. I have no clue why it prefers to swap to the SSD, rather than taking advantage of the 4 GB of unutilized RAM.

Re: M1 Mac SSD Swapping

#3

Post by eyelidlessness » Sun, Feb 14, 2021, 3:05 AM UTC

spideymans wrote: post #2

Even on the 16 GB model, the system very aggressively swaps. During my normal workflow, RAM usage is typically at 12 GB, with 4 GB free and 4 GB+ swapped to the SSD. I have no clue why it prefers to swap to the SSD, rather than taking advantage of the 4 GB of unutilized RAM.

I overly obsessively watch memory usage and in my usage this usually indicates a pattern of consuming most RAM then purging some of it (common example is closing a browser window with 10ish+ tabs). It’s not that the OS favors swap over RAM, but that it’s very conservative about bringing memory out of swap once it’s there, because it had already been designated as low priority and may deoptimize higher priority usage in new workloads.

Re: M1 Mac SSD Swapping

#4

Post by fsflyer » Sun, Feb 14, 2021, 3:06 AM UTC

Is it swap, or is it mds (spotlight) indexing?

Re: M1 Mac SSD Swapping

#5

Post by BearOso » Sun, Feb 14, 2021, 3:11 AM UTC

This is a whole drive write for every 6 hours of use. Modern TLC is usually only warrantied for about 600 drive writes, though it can usually go higher before failing.

So if you use your laptop for about 5 hours a day, you can expect the SSD to last at least 2 years. For an unswappable part, this is a short time.

They’re really abusing the flash and pushing it to the endurance limit. I personally switched over to all SSD when I discovered that my usage patterns would consume so little lifetime that it was a nonissue. This would make me paranoid again.

Re: M1 Mac SSD Swapping

#6

Post by phire » Sun, Feb 14, 2021, 3:54 AM UTC

fsflyer wrote: post #4

Is it swap, or is it mds (spotlight) indexing?

Indexing is a read heavy workload. It shouldn't be causing TBs of writes a day.

Re: M1 Mac SSD Swapping

#7

Post by spideymans » Sun, Feb 14, 2021, 4:33 AM UTC

eyelidlessness wrote: post #3

spideymans wrote: post #2

Even on the 16 GB model, the system very aggressively swaps. During my normal workflow, RAM usage is typically at 12 GB, with 4 GB free and 4 GB+ swapped to the SSD. I have no clue why it prefers to swap to the SSD, rather than taking advantage of the 4 GB of unutilized RAM.

I overly obsessively watch memory usage and in my usage this usually indicates a pattern of consuming most RAM then purging some of it (common example is closing a browser window with 10ish+ tabs). It’s not that the OS favors swap over RAM, but that it’s very conservative about bringing memory out of swap once it’s there, because it had already been designated as low priority and may deoptimize higher priority usage…

Interesting. I don't think that's the case here though. I obsessively watch Activity Monitor as well, and I've yet to see memory utilization ever go above 12.5 GB on my M1, despite the system using a large amount of swap.