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extreme · Apr 19, 2006, 10:41 PM

I have an iBook G4 1.33GHz 12-inch (mid-2005 edition) with Mac OS X 10.4.6 installed on it. I recently upgraded my RAM from built-in 512 MB to 1.5 GB. But since then i have noticed a strange thing. The amount of free memory is always very very less. For example, at this time I have one safari window open and 5 widgets (istat pro, calendar widget, 2 clock widgets and a weather widget) running in dashboard. But the amount of free RAM that i have is 340 MB. There are no other applications running. I had these same things running when I had a total of 512 MB RAM and now the same things are eating up around 1.1 GB of RAM. How is this possible? And by the way, the new RAM is perfectly fine. I have run Apple Hardware Test on it. I am attaching the screenshot of the istat pro info:

chabig · Apr 19, 2006, 10:45 PM

You spent good money on that RAM, and now you don't want OS X to use it? Seriously, the system will maximize the use of whatever RAM you install. Everything is operating normally with your machine.

Chris

mduell · Apr 19, 2006, 10:46 PM

As the other poster said, free memory is wasted memory. The OS uses available memory to cache the disk and provide better performance and a more responsive environment.

extreme · Apr 19, 2006, 11:13 PM

Oh, i didnt even think on those aspects... neways thnx for the replies guys... at least my tension is relieved now

chabig · Apr 19, 2006, 11:47 PM

We're glad to help. You are not the first to wonder about memory use. It's just a bit more modern than the older OSes.

Chris

Tomchu · Apr 20, 2006, 12:39 AM

Originally Posted by chabig

We're glad to help. You are not the first to wonder about memory use. It's just a bit more modern than the older OSes.

Chris

No, I'd say that almost every decently-complex OS has had some form of disk caching.

Hell, even DOS did in the form of SMARTDRV. I know that all of the *nixes have done it for ages.

Detrius · Apr 20, 2006, 02:02 AM

As your own pictures show, only about 470MB of your RAM is being actively used. The rest is either a cache or stuff that isn't being used at the moment. You should also take into account the fact that this shows that you really didn't have enough RAM to begin with.

If you do a search for your thread title in this forum, you will probably find a bazillion different threads discussing the exact same thing, all the way back to when 10.0 was released. OS 9 had horrible memory management. Free RAM is wasted RAM.

P · Apr 20, 2006, 01:06 PM

Originally Posted by Tomchu

No, I'd say that almost every decently-complex OS has had some form of disk caching.

Hell, even DOS did in the form of SMARTDRV. I know that all of the *nixes have done it for ages.

But DOS and Classic Mac OS didn't have a dynamic cache - the cache was set to a fixed value (on more recent Mac OS versions, the cache was calculated at startup from the amount of available memory, but that's not the same). The behaviour of Unixen to use all available memory is something that is very confusing at first. I'm not sure exactly what Win2k/XP does, but it does show a lot of free memory most of the time. I think that free memory is actually used for disk caching, but that the display hides this to avoid confusion.

Tomchu · Apr 20, 2006, 01:56 PM

Originally Posted by P

But DOS and Classic Mac OS didn't have a dynamic cache - the cache was set to a fixed value (on more recent Mac OS versions, the cache was calculated at startup from the amount of available memory, but that's not the same). The behaviour of Unixen to use all available memory is something that is very confusing at first. I'm not sure exactly what Win2k/XP does, but it does show a lot of free memory most of the time. I think that free memory is actually used for disk caching, but that the display hides this to avoid confusion.

You're right about that -- NT-based Windows disregards disk cache when it reports free RAM, but there are counters that keep track of disk cache as well.

TETENAL · Apr 20, 2006, 02:19 PM

Originally Posted by extreme

But the amount of free RAM that i have is 340 MB.

You're reading the statistics wrong. The amount of "free" RAM in the sense of "available for use" in your image is more than 1 GB. Read the following article:

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

kick52 · Apr 21, 2006, 07:19 AM

try optimizing your system. google onyx.

ChrisF · Apr 21, 2006, 08:10 AM

Originally Posted by kick52

try optimizing your system. google onyx.

Why would that help anything when what's going on is not a problem, nor even abnormal?

kick52 · Apr 21, 2006, 08:56 AM

well it would speed things up a bit, even if it doesnt fix the problem.

eevyl · Apr 21, 2006, 09:36 AM

Optimizing the system has subzero to do with memory usage, not to mention the OS automatically does it since Panther, so no need to force do it with a third party app.

CharlesS · Apr 21, 2006, 11:36 AM

Originally Posted by kick52

well it would speed things up a bit, even if it doesnt fix the problem.

No it won't. Onyx doesn't optimize the system, it just runs Repair Permissions and some outdated things like Update Prebinding which aren't really applicable anymore to OS X 10.4 and higher. It also runs the periodic scripts which get run automatically every day by launchd anyway.

Oh, it does delete some cache files. Which could make things run a bit slower, since the point of caches is to make things run faster.