What does Memory pressure color mean?

[Perfa]

Hi,

One of our Macs has 2GB memory. Mavericks was a real success on this machine, but I have yet to understand what the color means.

On this machine the color is always yellow (never green). Used memory could be below 2 gig, no swap file, but still yellow.

Also what is the definition of the actual hight of the pressure line? On the other machine with more mem the line has higher amplitude, but it is still green even tho it actually swaps now and then.

So one machine, no swap, yellow color and another machine has small swap, but color is green. It makes no sense.

I have read all about Mavericks memory management i can seam to find, but there is no info about the actual color coding.

Im sure Apple don't want me to bother and just chill but i want to understand the system.

Anyone?

 

[josh.b]

Hi,

One of our Macs has 2GB memory. Mavericks was a real success on this machine, but I have yet to understand what the color means.

On this machine the color is always yellow (never green). Used memory could be below 2 gig, no swap file, but still yellow.

Also what is the definition of the actual hight of the pressure line? On the other machine with more mem the line has higher amplitude, but it is still green even tho it actually swaps now and then.

So one machine, no swap, yellow color and another machine has small swap, but color is green. It makes no sense.

I have read all about Mavericks memory management i can seam to find, but there is no info about the actual color coding.

Im sure Apple don't want me to bother and just chill but i want to understand the system.

Anyone?

It is like traffic lights. Green = good to go, Yellow = caution get ready, Red = stop you need more ram

 

[Perfa]

It is like traffic lights. Green = good to go, Yellow = caution get ready, Red = stop you need more ram

Yeah I got that already! But thx anyway.

 

[Perfa]

Actually the only conclusion i could think of is that mem pressure color is not a function of swap used.

 

[leman]

The detailed mathematics behind the memory pressure calculation appear to be unknown at the moment though. I think its best understand it as how 'comfortable' the OS currently is with the RAM.

There is some interesting discussion on this topic here: http://apple.stackexchange.com/ques...sure-does-mavericks-memory-pressure-adhere-to

 

[ElectricSheep]

Memory Pressure is an inversely related to the ratio of pages available to total physical pages (total installed RAM. The number of pages "available" is computed as:

Number of External (file-mapped) Pages + Number of Free Pages + Number of Anonymously Mapped Pages flagged as Purgeable (if dynamic paging is enabled, which is almost always is).

5% and 15% are thresholds for internal level indicators "Critical" and "Urgent", but those may not directly correspond to the coloring of the pressure graph.

 

[Perfa]

Memory Pressure is an inversely related to the ratio of pages available to total physical pages (total installed RAM. The number of pages "available" is computed as:

Number of External (file-mapped) Pages + Number of Free Pages + Number of Anonymously Mapped Pages flagged as Purgeable (if dynamic paging is enabled, which is almost always is).

5% and 15% are thresholds for internal level indicators "Critical" and "Urgent", but those may not directly correspond to the coloring of the pressure graph.

That sounds to me like a simple and logical explanation. It explains my own experience of having high pressure even though there is free memory or no swap. Even though there are pages available they are few compared to total number of pages. Simple.