Why does memory usage go up every second?

[brianjanthony]

This probably means nothing, and I am just making an observaton here.

I am running Mac G5 dual 2 ghz machine. PT 7.1.10 HD and Mac OS X Tiger 10.4.6. Whilst watching "Activity Monitor." I noticed that the entire time I have PT open, the memory usage of PT creeps up every second or so. Small increments, mind you. But I opened a session with some VIs in it, and watched the memory usage creep from like 600 to 900 meg in a couple minutes. And it didn't seem to max out. Just kept climbing.

Is that normal?

I ask because over the course of a session day, sometimes my computer gets real flaky. Maybe I'm maxing out my RAM after leaving a session over for a while???


brian

[PhilBuckle]

There is a logical reason for this...........not that I fully understand it.
Here is a quote from the "Memory Stick" manual that explains quite a bit.
You can get Memory Stick on Version Tracker and see what your RAM is up to........
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A Mercifully Brief and Wildly Over-Simplified Lecture on How Mac OS X Uses Memory

The first thing you'll notice when you start up MemoryStick is that there are no applications listed. This is because in Mac OS X there are not distinct application heaps as in previous systems. Instead, every application is given the illusion that it has huge quantities of RAM available to it (much more than you probably have). Mac OS X maintains this illusion by means of its memory management system.

Under this system, Mac OS X loads into RAM the resources (bits of code, data, and so forth) that are actually needed. An application's actual RAM usage is thus dynamic. If an application loads all the data from a small document, it uses a small amount of RAM; if it loads all the data from a large document, it uses a large amount of RAM. If an applications quits, some of these resources are no longer needed, and RAM usage goes down (but, as MemoryStick reveals, not as much as one might expect).

This architecture has two chief advantages over earlier Mac systems. First, you can run lots of applications without necessarily using all that much RAM, because an application is not compelled to ask in advance for a big block of RAM that it might not need all of. Second, an application basically never runs out of memory, because there isn't some fixed block of memory beyond which it can never go. So you'll never see one of those messages saying that an application is running out of memory and can't open this document, complete this operation, or whatever. This, in fact, is probably one of the main reasons you're using Mac OS X as opposed to an earlier system.

Nevertheless, the fact is that your RAM is finite, so Mac OS X must do something if RAM gets tight (which could happen because there are a lot of windows open or a lot of applications running or whatever). What it does is to spool some less used resources off to the hard disk (into /var/vm, if you must know). This is called a "pageout". The idea is that in this way Mac OS X can use all the actual RAM available to it, and then if a resource is needed that was paged out to the hard disk, it can be read from the hard disk, exchanging it for some other less used resource. This is superficially similar to the earlier notion of "virtual memory". For example, if you're running AppA in the background and you open AppB which needs a lot of actual RAM, some of AppA's resources might get paged out; then if you switch back to AppA and do something that needs those resources, they are read back in, in exchange for some of AppB's resources.

The problem is that this process of pageout-and-swap is slow. For this reason, more RAM is better. So, you can perhaps run Mac OS X with just 128MB of RAM, but after a while you might start to see a lot of delays, with the dreaded "spinning cursor" showing up often. That's because Mac OS X is having to pageout and swap a lot of material in order to keep open all the applications you're using. On the other hand you might do the same work with 320MB of RAM and never see any delays at all.

MemoryStick's window consists primarily of a bar graph representing your whole RAM. Your RAM usage is displayed as four categories, each represented by a different color. That's all. You can hover the mouse over this bar graph, though, to learn what the colors mean and to see some numbers. The four categories are:

Wired. Wired resources are those that are absolutely needed in order to run; they are so fundamental that they will never be paged out of RAM.
Active. Active resources are those that have been loaded because some application needs them, and they are currently in use, so they won't be paged out right now.
Inactive. Inactive resources will usually be the predominant category. They may have already been paged out, but are also being kept in RAM so that if needed they will not have to be paged in, and access will be fast. The system is playing a kind of guessing-game here: these are resources that you used in the past and that your System thinks you might want to use again soon. Your inactive resources usage will grow and shrink over time. Think of it as a kind of scratch region of RAM.
Free. If the free region of RAM decreases enough, you'll probably start getting some pageouts. That is not necessarily a bad thing, unless it's happening more often than you really want. If it is, a solution might be to quit some apps, close some windows, or restart the computer.
If you find that both Free and Inactive memory are getting small, that is a bad sign: the hard disk is probably being used heavily, you're probably generating a lot of swapfiles, and you should probably restart the computer (and consider installing more RAM for the kind of work you're doing).
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The rest of the explanation is in the Memeory Stick help file.
Handy little utility.

[c-tone]

It seems like more and more RAM is being used, even though it isn't needed. The explaination given above makes it seem like memory is only used when needed by the program. Maybe this is a memory leak?

have a look at this thread

[brianjanthony]

I thought it might be a memory leak. Does everybody else witness this? Obviously, some people have (as referenced in the post linked to above). Digi? Is this a known issue? Is there any way to stop the ever-gobbling of RAM?? What is taking up the memory? Are there settings or an OS patch that make it go away?

brian

[brianjanthony]

bump

digi?

[DigiTechSupt]

Are you doing anything in Pro Tools when the memory usage is creeping up?

How much RAM do you have installed?

[Brandonx1]

For me, the memory invcreases when I copy, duplicate, move, an audio region.
Brandon

[CD Productions]

It hapens while I cut, crossfade, copy, paste, record eq automation, rerecord DX.....Basically, while I work. I'm not trying to be glib, but I can't isolate any one thing thats causing the slow down. It's just after a while the program slows down, and quitting and restarting gets it back up to speed.

[brianjanthony]

I have 4 gig of RAM. RAM seems to increase when I hit Play in Pro Tools. While the music is playing RAM increases. I hit stop, it doesn't go back down.

I'll double check this tomorrow out at the studio. Only thing I cannot remember exactly is if it climbs even after I hit stop.

brian

[Tweakhead]

Already reported in these threads.

http://duc.digidesign.com/showflat.php?Number=1058676

http://duc.digidesign.com/showflat.php?Number=1067863


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