Hi there,
I've looked up my MacBook Pro 15'' Retina's activity log and I mentioned that it was using over 7GB of memory, yet the MacBook itself has 8Gb available. If I may believe activity log, over 4GB of memory was used by apps, 1.5GB was wired memory and the rest was cached.
Is 4.5GB of usage normal for a standard Mac OS X Mavericks configuration? As I see right now, Safari takes only 300 Mb and Google Drive uses 'just' 150 Mb of memory. Over 1 GB is used by something called kernel task (don't know what it is). Does anyone know if this normal? Could it eventually slow down your Mac's performance?
Thanks!
You don't understand how to read RAM in OSX Mavericks. You are not taking into account RAM compression, App Cache, and RAM pressure. Here is an example:
When having iMovie open with a large video, and Chrome with a 5-10 tabs, I am using 6Gb of my 8Gb of RAM. The system can then use another 2Gb before it hits the total, where is will start to clear App Cache, then another 2-3Gb (App Cache) before it starts compressing RAM, then another 4-6Gb before touching Swap (ie- ran out of RAM). So in this circumstance, using 6Gb of RAM is using 31.5% before I run out of RAM.
If your RAM pressure is red and you are a Swap/Page-out larger than a few Kb then your Macbook has ran out of RAM. If it is green, and you still have a lot of cache left, you are using a tiny amount.
With RAM compression, I had all of my applications open, iMovie doing some exporting, and 100 tabs split between Chrome and Safari (around 50/50 each) and I was using 15.14Gb of RAM with my 8Gb of RAM iMac . And it still never touched swap. And my RAM compression was green. This is due to the heavy caching OSX does (to make apps launch instantly, rather than fetching data from backing storage which is a much slower process) as well as RAM compression. RAM compression uses the WKdm compression algorithm allowing data held in RAM to be compressed and decompressed almost instantly meaning you can have a lot more running before you run out of RAM. As said above, I use using 15.15Gb of RAM (and my iMac has 8Gb). What this means, is that the data within RAM consisted of 15.14Gb (with some being compressed to make it fit on the 2X4Gb modules, but then instantly decompressed when needed).
Another thing to note, is that when I was using this much, my iMac was still very responsive (90% as responsive when compared to not pushing it). RAM pressure was also green, meaning I could push around 17Gb of RAM on my 8Gb system.
I hope this has helped you understand how RAM works in Mavericks. When you see "Memory Used: 7.xx", don't just think you are using all of it. Look at App Cache then add that number on to your total RAM (i.e 7.xx out of 10/11Gb of RAM used, rather than 7.xx out of 8Gb used), then look at Compressed RAM and if 0 add 6Gb again on to your total. In the end, you are using 7Gb out of 17Gb. Also look at RAM pressure: green indicated you have loads of free RAM, amber indicated you are pushing the system RAM but there is still RAM free, and red indicated you have ran out of RAM and data has to be swapped to disk.
But doesn't this affect the battery life of my MacBook?
