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TyroneShoes2

macrumors regular
Aug 17, 2011
133
3
What exactly is that advantage?...
To me, that is still unclear. If you read between the lines of the article link, it may refer to cache memory. IOW, stuff can be offloaded to the VM file on a HDD or SDD, or it can be offloaded to L3 or other cache (not sure if L3 is still used). Since cached data is acquired as fast as, or even faster than RAM (due to how fast the bus may or may not be) there is an advantage to offloading data to a cache. Maybe this is what we are talking about.

Ironically, the G3 chip originally processed significantly faster in the real world than the G4 chip because the G3 development team concentrated on having a lot of L3 cache while the G4 team did not. This was difficult to explain, and resulted in a lot of chips being plowed under to cover this fact up (source: Leo LaPorte on MacBreak Weekly).

So if we assume that this is what they are referring to as "Inactive" memory. and I am purely speculating here, that would at least explain why it may have an "advantage" that free memory (memory unused and sitting in RAM) might not.

The obvious question then becomes "what does 'purge' do?". Does this mean that when you invoke a purge command that it blows that memory out of cached status and back into free memory?

If so, then it makes sense not to invoke it if you expect to reload recent documents or apps. And it seems then not to matter if you don't expect to. And even then, any "advantage" seems pretty minor.

Especially in the era of SSDs. It would seem that accessing RAM, while significantly faster than accessing a HDD, might not be all that different than accessing an SSD. That means the "advantage" of cache memory is even less than it would be with a standard HDD, and the same applies to how much virtual memory there is being used, and to the page ins and page outs.

Can anyone confirm or deny any of this?
 

twintin

macrumors 6502a
Aug 10, 2012
710
238
Sweden
Isn't the 260 GB virtual memory file a little alarming? With a 128 GB SSD (as stated in the OPs specs), where does that even reside?

Think you are mixing up VM size with swap file size. They may appear same, but are evidently not (just compare the VM size with amount of free disk space in Activity Monitor).
 

Kludge420

macrumors regular
Apr 20, 2009
114
0
Restart your computer, then follow the instructions in my earlier post to take a new screen shot and post it. Don't skip any steps.

That is not necessary. Inactive RAM is available for use, just like free memory, except it has an added advantage. Purging removes that advantage.

Wrong and wrong. You have no idea what you are talking about. Do NOT restart your computer but instead run purge as was stated. Also inactive memory is NOT available to other apps but only the app that has the memory leak (probably a Chrome plugin) that's eating up all his free memory so there is zero advantage. Saying to reboot is ridiculous since that would, in effect, purge the memory but would take longer.
 
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twintin

macrumors 6502a
Aug 10, 2012
710
238
Sweden
Also inactive memory is NOT available to other apps but only the app that has the memory leak (probably a Chrome plugin) that's eating up all his free memory so there is zero advantage.

Seriously, this is pretty standard Unix memory management. You can google NetBSD, FreeBSD or Linux and you will see they pretty much all work in same way as OS X when it comes to memory management.

Here is an article for you explaining OS X memory management.

http://sg80bab.blogspot.se/2007/03/is-my-mac-using-too-much-memory.html
 
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TyroneShoes2

macrumors regular
Aug 17, 2011
133
3
Isn't the 260 GB virtual memory file a little alarming? With a 128 GB SSD (as stated in the OPs specs), where does that even reside?...
Think you are mixing up VM size with swap file size. They may appear same, but are evidently not (just compare the VM size with amount of free disk space in Activity Monitor).
Am I? Apple doesn't even use the terminology "swap file" so that is a part of what I don't understand; I need that definition.

Indiana University information technology services knowledge base seems to define VM as a system comprising of Ram and HDD space using an algorithm to park data in RAM in a HDD file during multitasking so that that RAM is freed up for use when a different task is being requested of the computer. Put more simply, data in RAM is temporarily off-loaded to a file on the HDD when not actively being addressed. So it is RAM, HDD space, and a particular implementation of the two. And that is not in any way different from the understanding that I already had.

They go further to imply that a "swap file" is indeed that file on the HDD that VM uses. Again, that has always been my understanding as well.

If all of that is true, then wtf is the VM size reported in Activity Monitor? Is that the accrued amount of data that is swapped since bootup? One would assume that it is not if the pages in and out are also listed as being this low, so I still do not understand what VM size is referring to.
 

GGJstudios

macrumors Westmere
May 16, 2008
44,537
940
Wrong and wrong. You have no idea what you are talking about.
Before you erroneously claim someone is wrong, you might want to read up on the topic so you don't embarrass yourself.
Do NOT restart your computer but instead run purge as was stated.
Purge does not reset page outs and swap used to zero, as a restart does.
Also inactive memory is NOT available to other apps but only the app that has the memory leak (probably a Chrome plugin) that's eating up all his free memory so there is zero advantage.
That is false. From the link I posted earlier:
Inactive:

This information is in RAM but it is not actively being used, it was recently used.

For example, if you've been using Mail and then quit it, the RAM that Mail was using is marked as Inactive memory. 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.
Saying to reboot is ridiculous since that would, in effect, purge the memory but would take longer.
Again, purge doesn't reset page outs and swap used, which is the purpose of the restart, so those can be tracked from zero. Page outs are cumulative since the last restart.
 

Kludge420

macrumors regular
Apr 20, 2009
114
0
Before you erroneously claim someone is wrong, you might want to read up on the topic so you don't embarrass yourself.

Back at ya. The reason he has so much page outs and swap usage is exactly because he has all that memory tied up as inactive. Running purge will almost instantly drop the drive hits and speed up the Mac. Since you have no practicle knowledge and are simply regurgitating partially understood docs you might want to stop before you make more of a fool of yourself.
 

dyn

macrumors 68030
Aug 8, 2009
2,708
387
.nl
Wrong and wrong. You have no idea what you are talking about. Do NOT restart your computer but instead run purge as was stated.
The only one having absolutely no idea about memory whatsoever would be you. From the manual for the purge command:

NAME
purge -- force disk cache to be purged (flushed and emptied)

SYNOPSIS
purge

DESCRIPTION
Purge can be used to approximate initial boot conditions with a cold disk buffer cache for performance
analysis. It does not affect anonymous memory that has been allocated through malloc, vm_allocate, etc.

SEE ALSO
sync(8), malloc(3)

Purge only flushes disk cache, not the other things that are in memory. A reboot does EVERYTHING. That's the major difference and the reason why rebooting is a much better idea. Using purge has also some nasty side effects such as a very slow computer right after completing the purge and even crashing apps (not every apps likes what purge does). This is the main reason why you shouldn't be using purge but be doing a reboot.

The effect of the purge command varies greatly. It depends on how much of the memory is being used as disk cache. If it is a lot you can regain a lot of memory, if it isn't then you don't regain a lot of memory (aka stating the obvious).

Also inactive memory is NOT available to other apps but only the app that has the memory leak (probably a Chrome plugin) that's eating up all his free memory so there is zero advantage.
It is the OS that handles the memory and not the applications. The applications will request but it is the OS who decides what the apps will get. Of course apps can only reach what they have been given. If they could reach the area in memory for other apps this is a major bug in terms of security and safety (stealing mem from other apps will make them crash, corrupt data and many other nasty things).

One thing you are correct about: using purge will indeed do nothing with the inactive memory (it has zero advantage) thus requiring the user to reboot in order to reclaim inactive memory.

Check out post #2 by simsaladimbamba. It contains a link to the official Apple knowledge base where they explain OS X's memory management. You definitely won't like what it says under "inactive memory" as it shows that you are nothing more than a simple troll:
Inactive:

This information is in RAM but it is not actively being used, it was recently used.

For example, if you've been using Mail and then quit it, the RAM that Mail was using is marked as Inactive memory. 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.
 

GGJstudios

macrumors Westmere
May 16, 2008
44,537
940
Back at ya. The reason he has so much page outs and swap usage is exactly because he has all that memory tied up as inactive.
Your posts indicate you have much to learn about Mac OS X memory management. Page outs and swap usage are a result of no free or inactive memory available. Purge simply removes the one advantage of having inactive memory, and nothing more, since inactive memory is the same as free memory in all other respects.
Since you have no practicle knowledge and are simply regurgitating partially understood docs you might want to stop before you make more of a fool of yourself.
I actually have more than a few years of practical knowledge, and can even correctly spell "practical". You have no idea what I do or don't understand, and since my statements about Mac OS X memory are supported by statements from Apple, who developed Mac OS X, I'll trust my knowledge and understanding on this one. You've been presented with the facts. If you choose to ignore the facts, that's up to you.
 

Kludge420

macrumors regular
Apr 20, 2009
114
0
Your posts indicate you have much to learn about Mac OS X memory management. Page outs and swap usage are a result of no free or inactive memory available. Purge simply removes the one advantage of having inactive memory, and nothing more, since inactive memory is the same as free memory in all other respects.

I actually have more than a few years of practical knowledge, and can even correctly spell "practical". You have no idea what I do or don't understand, and since my statements about Mac OS X memory are supported by statements from Apple, who developed Mac OS X, I'll trust my knowledge and understanding on this one. You've been presented with the facts. If you choose to ignore the facts, that's up to you.

You know you've won when all they can address is a spelling mistake.

The reality is purge works: end of discussion.
 

GGJstudios

macrumors Westmere
May 16, 2008
44,537
940
You know you've won when all they can address is a spelling mistake.
That indicates that you didn't read the rest of the post. You can keep denying the facts, but that doesn't make them any less true.
 
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