What Exactly Is Page Ins/Outs?

soLoredd

macrumors 6502a
Original poster
Mar 12, 2007
967
0
California
Well, for awhile now I've been curious as to how OS X handles memory. I remember reading something awhile back that said if you notice a lot of page outs in Activity Monitor that you need more RAM. Well, I got 2GB today and installed it into my MacBook, thinking this would take care of the page outs. While running iCal, Mail, iTunes, and Safari my page outs are appearing again. Is it something to really worry about?

Also, I figured the extra 1GB of RAM would help Parallels but so far it hasn't. While using Vista, Parallels crawls at times even though I've allocated 1GB of RAM to it. Is this just more of a limitation of my MacBook?

Thanks for any answers or info! :)
 

Queso

Suspended
Mar 4, 2006
11,824
7
Page In/Outs relate to how OSX is using virtual memory, which is basically where the state of running processes is written to the hard disk to free up RAM for higher-priority stuff. If the number of Page In/Outs is constantly excessive it means that your system is having to do this in normal operation rather than just at times of heavy load, so it's a good indicator that the number of processes you have running justifies more RAM being installed.

Otherwise you are stressing your hard disk unnecessarily, which could lead to an early failure. At the same time your system will be running far slower than it should be doing.
 

DoFoT9

macrumors P6
Jun 11, 2007
17,530
32
Singapore
pagesin/outs are the swaps of virtual memory that the computer does....

this isnt a correct analogy but itl do.
say for instance u have Just filled up ur raml, you have safari (which you havent used for 30mins) and photoshop(which ur using now). the safari ram has been swapped into virtual memory, to allow extra space for photoshop and other applications. it is this "swapped memory" that is called the pagein/outs. so if safari could get rid of 64mb of ram and chuck it into VM your page would be 64mb...

that is my understanding of it. correct me if im wrong!!!
 

soLoredd

macrumors 6502a
Original poster
Mar 12, 2007
967
0
California
Thanks for the replies. I was kind of thinking the same thing - it was the number of times the VM has been accessed both to and from. There probably is no reason to worry about it :)