Physical Memory Usage

[Verdanice]

Hi,

I've got a question regarding physical memory usage on my 15" 2.4GHz SR/2GB Macbook Pro.

I understand memory management on Windows, but I'm not totally clear about OS X's. I have 2GB of RAM in this machine, and when I run paralells and/or Photoshop with Firefox, Adium, Mail, and aybe Pages/Transmission, my physcal ram availability is totally decimated. What I don't understand is why the physical usage of each process in Activity Monitor don't add up to nearly what is apparently being used. See the screenshot:

Could somebody fill me in on this? I'm sure somebody's asked about this before but I couldn't find an exact match with a forum search. If you could link to a response that would be great.

I appreciate your help! Thanks in advance.

 

[thegrifman]

I know I've read it here before but I can't find the post right now, but here's a link to Apples online docs detailing how to read the memory usage. Basically your Inactive RAM is from things that no app is using but is kept there until it's needed again. If something else needs that space then it's readily overwritten so technicall you've got about 700mb of available RAM.

http://docs.info.apple.com/article.html?artnum=107918

 

[Verdanice]

I know I've read it here before but I can't find the post right now, but here's a link to Apples online docs detailing how to read the memory usage. Basically your Inactive RAM is from things that no app is using but is kept there until it's needed again. If something else needs that space then it's readily overwritten so technicall you've got about 700mb of available RAM.

http://docs.info.apple.com/article.html?artnum=107918

Thanks for the response.

That makes some sense, but t doesn't totally explain that my system pretty much grinds to a halt at that point - as soon as the available memory is that low, the system acts like it.

 

[Chris F]

Actually your picture looks OKish to me. You dont have many page outs which means you are not actively hitting the disk quite yet. Your wired + active memory is at about 1.35GB so about 66% of your physical memory is being actively used.

You will probably notice a bit of a slow down because the system no longer has a huge memory cache (the inactive portion) to use to make things go faster. You will also notice a bit of slowdown because you are taxing the system quite a bit running multiple resource heavy applications (photoshop, parallels, firefox/safari).

Anyhow if you plan to run parallels or photoshop all the time in conjunction with everything else (and why wouldent you?) upgrading to 4GB (cost: ~$260USD) would be a good move.

 

[thegrifman]

Anyhow if you plan to run parallels or photoshop all the time in conjunction with everything else (and why wouldent you?) upgrading to 4GB (cost: ~$260USD) would be a good move.

Definitely! I run Vista in a virtual machine on occassion and I'm able to allocate an entire gig of ram to it since I upgraded to 3Gb in my mbp so a RAM upgrade sounds like a good idea for you.

 

[Verdanice]

Thanks guys.

I'm considering the upgrade and have been since purchase (it's incredible that Apple charges nearly $800 for the upgrade from 2GB to 4.

I suppose I'll just have to find that balance for now until I can scrape ogether about $300 (damn the Canadian economy for getting above the USD but providing zero benefits domestically to the consumer).. Thanks for your responses!