Here is the mac that i have. I want to upgrade from snow l. to mt, lion when it comes out. articles are saying that i will need 4gb even though the updae page says 2gb. how do i read the activity monitor to see if i need more ram for the update? or do i just need to wait, install teh update, and then check? I want to get this all done in the next month so help would be great!
Macbook Pro, Mac OS X (10.5.8)
This is my mac specs
2 GBs is the minimum required. 4 GBs or more would be better. Your model supports up to 8 GBs.
About OS X Memory Management and Usage
Reading system memory usage in Activity Monitor
Performance Guidelines- Memory Management in Mac OS X
A detailed look at memory usage in OS X
Understanding top output in the Terminal
The amount of available RAM for applications is the sum of Free RAM and Inactive RAM. This will change as applications are opened and closed or change from active to inactive status. The Swap figure represents an estimate of the total amount of swap space required for VM if used, but does not necessarily indicate the actual size of the existing swap file. If you are really in need of more RAM that would be indicated by how frequently the system uses VM. If you open the Terminal and run the top command at the prompt you will find information reported on Pageins () and Pageouts (). Pageouts () is the important figure. If the value in the parentheses is 0 (zero) then OS X is not making instantaneous use of VM which means you have adequate physical RAM for the system with the applications you have loaded. If the figure in parentheses is running positive and your hard drive is constantly being used (thrashing) then you need more physical RAM.
Adding RAM only makes it possible to run more programs concurrently. It doesn't speed up the computer nor make games run faster. What it can do is prevent the system from having to use disk-based VM when it runs out of RAM because you are trying to run too many applications concurrently or using applications that are extremely RAM dependent. It will improve the performance of applications that run mostly in RAM or when loading programs.
I like to start an Applications -> Utilities -> Terminal session, and then run the following command:
sar -g 60 100
which will report the number of pageouts every minute for 100 minutes (adjust the values to suit your tastes).
Now use your Mac as you normally would. Come back later and review the pageout values in your Terminal session.
If you have mostly zeros, or an occasional blip that you never noticed while actually using the system, you have sufficient RAM for your usage.
If you have sustained pageout activity, especially if you have high values, then you should either stop running so many concurrent apps, or get more RAM.
If you see short bursts of pageout activity every time you switch apps, then you are between the "good enough" zone, and the "it is annoying that switching apps is so slow" zone. You may want to consider more RAM, or live with it.
If you see this behavior with your current Mac OS X version, then most likely you will see it when you upgrade. However, if you do not see serious pageout activity now, that does not mean it will stay the same when you do upgrade, so you should be prepared to monitor your pageout activity again after the upgrade and you have settled into normal usage pattern.
so how do i know if i need more ram? (upgrade from snow->mt. lion)
