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Interpreting RAM usage stats from Activity Monitor

M

macbook123

macrumors 68000
Original poster
Feb 11, 2006
1,869
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In a typical session with my RMBP I accrue a lot of page ins, some page outs, and some amount of swap. I'd like to understand what these mean.

For example, currently I have 58 GB of page ins, 2.5 GB of page outs, and 7.9 GB of Swap used.

Which one of these numbers is the best indicator for "lack of RAM"? What do the others tell me?

Also, anybody have a clue why Apple is selling the high end model in the their retail stores only with 8 GB of RAM? The people working there tell me that it's because with the fast SSD RAM is much less important than it used to be. Clearly people here seem to disagree with this assessment. But why is Apple higher management not aware of it being an issue, if it is?
 
macbook123 said:
In a typical session with my RMBP I accrue a lot of page ins, some page outs, and some amount of swap. I'd like to understand what these mean.

For example, currently I have 58 GB of page ins, 2.5 GB of page outs, and 7.9 GB of Swap used.

Which one of these numbers is the best indicator for "lack of RAM"? What do the others tell me?
Click to expand...
You will always have page ins, so there's no need to track that. To determine if you can benefit from more RAM, launch Activity Monitor and click the System Memory tab at the bottom to check your page outs. Page outs are cumulative since your last restart, so the best way to check is to restart your computer and track page outs under your normal workload (the apps, browser pages and documents you normally would have open). If your page outs are significant (say 1GB or more) under normal use, you may benefit from more RAM. If your page outs are zero or very low during normal use, you probably won't see any performance improvement from adding RAM.

Mac OS X: Reading system memory usage in Activity Monitor

macbook123 said:
Also, anybody have a clue why Apple is selling the high end model in the their retail stores only with 8 GB of RAM? The people working there tell me that it's because with the fast SSD RAM is much less important than it used to be.
Click to expand...
If you exceed RAM and start paging, that process will be faster with a SSD than a HDD, but still considerably slower than not paging at all, as both HDD and SSD access times are much slower than RAM. All 2011 and 2012 MBPs can use up to 16GB of RAM.

You can find specs on all Apple products, including maximum RAM:
 
Don't just check for pageouts - if you notice a significant amount of "Inactive" memory while paging out, then OSX is failing to free it up as it should. To manually free Inactive memory, type "Purge" into the terminal and press enter. It'll take a few second to clear. Unfortunately this is an annoying process, which is why it's more convenient to just default to buying more RAM.
 
Dangerous Theory said:
Don't just check for pageouts - if you notice a significant amount of "Inactive" memory while paging out, then OSX is failing to free it up as it should. To manually free Inactive memory, type "Purge" into the terminal and press enter. It'll take a few second to clear. Unfortunately this is an annoying process, which is why it's more convenient to just default to buying more RAM.
Click to expand...
There is no need to purge inactive memory, and doing so can degrade performance, rather than improve it, as it removes the advantage that inactive memory has.
Inactive memory is available for use by another application, just like Free memory. However, if you open Mail before its Inactive memory is used by a different application, Mail will open quicker because its Inactive memory is converted to Active memory, instead of loading it from the slower drive.
Click to expand...
Also, page outs could have occurred at a time when all free and inactive memory was used, but is no longer being used. The page outs will remain, as they are cumulative, even though you may see free and/or inactive memory available at the time you look at Activity Monitor.
 
GGJstudios said:
The fact that you may benefit from more RAM isn't diminished by the fact that you can't upgrade it.
Click to expand...

Yup, but it's a moot point with a system that can't be upgraded. He would benefit a great deal more from conserving RAM wherever possible.
 
mikeo007 said:
Yup, but it's a moot point with a system that can't be upgraded. He would benefit a great deal more from conserving RAM wherever possible.
Click to expand...
The OP is asking how to read the memory stats, not how to upgrade their RAM. It's not a moot point when the goal is understanding memory readings.
 
GGJstudios said:
The OP is asking how to read the memory stats, not how to upgrade their RAM. It's not a moot point when the goal is understanding memory readings.
Click to expand...

And what do you think his next question may be? Trying to be proactive here and offer a reasonable solution if he finds that he is suffering from excessive paging.
 
mikeo007 said:
And what do you think his next question may be?
Click to expand...
Only the OP knows that answer.
mikeo007 said:
Trying to be proactive here and offer a reasonable solution if he finds that he is suffering from excessive paging.
Click to expand...
I'm sure the OP realizes the RAM in the MBPR isn't upgradable. They simply wanted to know what the readings mean and how to interpret them.
 
GGJstudios said:
Only the OP knows that answer.

I'm sure the OP realizes the RAM in the MBPR isn't upgradable. They simply wanted to know what the readings mean and how to interpret them.
Click to expand...

Ok, great assumption.

OP: If you want more info after you determine your paging situation, just bump this thread.
 
GGJstudios said:
There is no need to purge inactive memory, and doing so can degrade performance, rather than improve it, as it removes the advantage that inactive memory has.

Also, page outs could have occurred at a time when all free and inactive memory was used, but is no longer being used. The page outs will remain, as they are cumulative, even though you may see free and/or inactive memory available at the time you look at Activity Monitor.
Click to expand...

I'm talking about page outs that are happening in real time, not in the past. I have to disagree with you, there have been many occasions where I've had like 1.5GB inactive memory and no free memory and I'll get a nasty lagfest due to paging. I always resolve it by purging the memory, so maybe our usage patterns differ or you've just had a different experience, but I definitely suggest people try it if they notice paging out and loads of inactive memory.
 
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