Can I monitor memory pressure over a long time?

[Kaitlyn2004]

New to mac and looking to get a macbook pro... unsure about 24gb or 48gb ram. Contemplating just buying the 24gb especially with the holiday return, and see if that's enough.

I see people talk about "memory pressure" which is a new concept to me. I know generally speaking the OS and apps will use up as much RAM as you have, so RAM usage itself isn't a good measure.

Could I order the 24gb laptop, use that system info view to monitor memory pressure (while I do heavy lifting) and get a concrete idea about whether 24gb is enough or not? Would I need to visually constantly monitor it, or can I see the pressure usage over time, and understand whether it's just a quick blip or hangs out in high pressure for a bit?

 

[Basic75]

Sure, open Terminal.app and use the command

vm_stat 1 > vm_stat.out

to get a log of memory usage and paging activity etc.

 

[Ben J.]

Sure, open Terminal.app and use the command

vm_stat 1 > vm_stat.out

to get a log of memory usage and paging activity etc.

For me, that command starts the vm_stat process in the background and there is no info. I found this:

How to read Vmstat output - Red Hat Customer Portal

How i can read vmstat output

access.redhat.com

For us not fluent in terminalese, Activity Monitor app is the way to go:

Activity Monitor User Guide for Mac

Learn how to use Activity Monitor on your Mac to view information about how apps are using the processor, disks, memory, network, and more.

support.apple.com

 

[Basic75]

For me, that command starts the vm_stat process in the background and there is no info.

It doesn't start it in the background, it merely writes the output to vm_stat.out for later inspection.

 

[gilby101]

Sure, open Terminal.app and use the command

vm_stat 1 > vm_stat.out

to get a log of memory usage and paging activity etc.

The OP did ask for memory pressure. vm_stat is the key for scripting memory parameters, but does not include pressure. memory_pressure includes the inverse of pressure in its last line.

Would I need to visually constantly monitor it, or can I see the pressure usage over time, and understand whether it's just a quick blip or hangs out in high pressure for a bit?

You can do some scripting to collect memory stats at regular intervals. I use both memory_pressure and vm_stat to collect memory stats.

But easier is to use one of the system monitoring tools. The best is iStats Menus https://bjango.com/mac/istatmenus/ (not free) This incudes monitoring memory including pressure. The graph is rather boring on my 96GB iMac, but here is the last 3 days memory pressure.