From what I have read in this forum, the consensus is that most people don't need 8 gig ram. So I experimented with having multiple pages in Safari, Adobe Pro, Mail and MS Word open this is what I typically have when I am working. In the activity monitor, it shows that anywhere from 3.60 to 3.90 of my 4 G ram is in use, unless I am misunderstanding the readout (attached). Can anyone help me understand this? I am going to buy a new MBA, to want to understand if I really do need to upgrade to 8G or not. Thanks.
Just because the activity monitor shows that 3.9GB of 4GB is being used, doesn't mean that it is actually IN USE. The memory that is used is either buffered, and/or cached, preventing an application from having to make a call out to the hardware to allocate memory to it. It would simply pull it from cache instead of making the additional call, preventing I/O contention.
Additionally, that memory could be buffered ahead of time, similar to how Youtube would buffer the stream of a video so you could watch it without any pausing or interruption.
Finally, like in Windows, Linux, and other OSes, there is a swap partition that pages get swapped in and out of memory for.
I currently have Safari, Postbox, GIMP, XQuartz, SublimeText, iTunes, and the App store running, and I show 3.6GB out of 4GB being used, with 475MB unused. Yet I have, according to the Activity monitor, 5GB of Virtual memory (swap) used, but my apps are only using 1.7GB. The remaining 1.9GB is buffered or cached.
So while it states that nearly all of your memory is being used, it doesn't mean that it is actually in use.
BL.