How to understand memory pressure on Mac
Memory pressure shows how well the Mac’s memory is serving its current workload. Read the pressure trend in Activity Monitor alongside Memory Used, Cached Files, Compressed and Swap Used. Similar RAM usage can accompany different levels of pressure, so compare the readings over time while you repeat the task you care about.
Read the pressure graph with the other figures
Open Activity Monitor and choose Memory. Apple explains that its pressure graph considers free memory, the swap rate, wired memory and file caching. Watch whether pressure rises during your task and whether it settles afterward.
Cached Files shows data the system keeps in available memory for reuse. Compressed shows how much memory has been compressed to make room. Swap Used shows how much startup disk space is in use for swap. The amount in swap and the rate of swapping are different measurements.
Compare two readings with similar RAM use
Imagine a 16 GB Mac using about 13 GB while a document and browser are open. The pressure graph is steady and Swap Used stays roughly where it was. Now imagine the same Mac using about 13 GB during a large image export while pressure stays higher and Swap Used rises.
These are fictional observations. The second pattern gives you a reason to check how the export behaves when fewer other tasks are active. Record pressure and swap before the export, during it and after it finishes. The three readings give more context than one memory percentage.
- Note pressure and Swap Used before the task.
- Check both while the task runs.
- Observe whether pressure settles after the task finishes.
Check the Memory card in Wisp
Wisp’s dashboard Memory card shows memory in use, wired and compressed readings, and a pressure badge. The badge can read Normal, Elevated, High or Unavailable. Open Wisp’s Memory view to see swap as well.
Use the badge to decide when to open the Memory view for context. Read Activity Monitor’s own graph when you need Apple’s view of pressure. The two displays present pressure differently, so compare trends in each display without assigning a fixed equivalence.
Distinguish a spike from a sustained pattern
A pressure spike that falls when an export ends and elevated pressure that continues through several stages describe different observations. In the first case, note what started and ended the spike. In the second, note whether Swap Used also rose and whether the export or other apps became slower.
Swap Used may still be above its earlier level when pressure falls. Compare its direction during the work with how pressure and responsiveness changed. Save the time of each observation if you need to compare another run.
Questions
Is high RAM use enough to tell whether my Mac needs more memory?
Look at the pressure trend and how the task feels as well. Check whether pressure stays high and how swap changes while you repeat the workload.
What does Swap Used tell me?
It shows the amount of startup disk space currently used for swap. Compare it over time to see whether it rises during the task.
Where can I see compressed memory in Wisp?
Look at Compressed on the dashboard’s Memory card. The Memory view gives you more context, including swap.