Q: Lion - Memory Usage Problems

Michelasso wrote:

 

Anyway I am surprised that R-C-R didn't correct you already: XNU, the OS X kernel, is not a FreeBSD kernel. It's an hybrid one. It consists on the Mach microkernel (to which the virtual memory belongs) with components from FreeBSD and the I/O kit for writing drivers. Thus I am afraid that what you know about FreeBSD memory management must be revised when talking about OS X.

I already know this. Which is why I try to dwell as little as possible into specifics and direct comparisons.

In any case, the differences in the VM principles are not that significant. Terminology does differ though.

You did your purge test, got some results. What is your explanation of those observations?

Do you still believe that buffer memory is speculative memory? What was freed form the 'active' memory?

dkalchev wrote:

 

You did your purge test, got some results. What is your explanation of those observations?

 

1. Do you still believe that buffer memory is speculative memory?

2. What was freed form the 'active' memory?

1. Yes, or at least it fits with everything I understood now. Also I couldn't find any mention of the UCB in the virtual memory source code.

2. All pages freed from active, speculative and inactive memory become free pages as reported by vm_stat. Just sum the deltas and you'll get the numbers.

It is left to understand what purge is really supposed to do at this point. How and why it frees a page instead of another. But basically in all my tests what gets freed the most is the speculative memory. That usually goes down to a minimum of 4-5000 pages. The kernel doesn't allow it to go down a well defined limit anyway. I just can't find the "purge" source code, That would explain a bit (my programming skills are rusty).

There is some discussion on purge here:

http://stackoverflow.com/questions/459537/clear-buffer-cache-on-mac-os-x

Michelasso wrote:

Like everything Google must be used with a grain of salt. One has to select the relevant information.It did happen to me to find technotes or patch changelogs that talked about memory leaks in a couple of applications. As it is common knowledge, for example, that AdBlock and Safari for OS X are memory hungry.

The problem with this kind of so-called common knowledge is "memory hungry" is a vague term that can mean anything from a genuine memory leak to the amount of memory necessary for acceptable performance or to implement some desirable feature.

Often, it means nothing more that something uses more memory than something else only superficially similar. That kind of apples to oranges comparison is quite common but doesn't really qualify as knowledge.

R C-R wrote:

 

The problem with this kind of so-called common knowledge is "memory hungry" is a vague term that can mean anything from a genuine memory leak to the amount of memory necessary for acceptable performance or to implement some desirable feature.

 

Often, it means nothing more that something uses more memory than something else only superficially similar. That kind of apples to oranges comparison is quite common but doesn't really qualify as knowledge.

Sure, It is true though that after installing Lion I (and others) noticed that Safari was eating a lot of memory. Checking around many suggested that AdBlock was one of the causes. I disabled AdBlock and Safari started to use noticeably less memory. Also it is known that Safari, not like Chrome for example, doesn't release memory closing the tabs. Which means that once it has eaten the memory it can only want more. Which is hunger to me (leading to famine in the third world Macs like mine).

Hi John Kitchen - just thinking about upgrading my late-2009 Macbook Pro to 8GB RAM, from 4GB. I'm using Lion. Did you notice a decent bump in speed? Is it worth it?

Thanks

John, I have a 2009 MBP and upgraded to 8GM ram and it helped a lot. Also, by disconnecting and UNinstalling Carbonite helped a ton. That was sucking the life out of the computer. Now, I am back to an external drive for backups.

I have had similar issues with BackBlaze cloud backup using enormous processing power in Lion, at the expense of greatly slowing down everything else. I do not know whether this is a Lion problem or a third-party problem, but I can say without question that under Snow Leopard, I did not have this issue.

LInczs wrote regarding BackBlaze:

 

I do not know whether this is a Lion problem or a third-party problem, but I can say without question that under Snow Leopard, I did not have this issue.

When something works without problems with one OS version but not the next, it often means it needs to be updated to a version compatible with the later OS. It also can mean that one or more of the the installed version's support files (like preferences) have been damaged or corrupted.

So to resolve such issues start by making sure you have the latest version of the software installed on your Mac. If it includes an uninstaller, it is sometimes useful to first uninstall it & then reinstall the newest version. If you know where its preference file(s) are located, it can also help to move them to the desktop & relaunch the software.

If all else fails, it is a good idea to contact the developer to see if there are any known issues or suggested procedures to resolve the issue.

I've not read all 49 pages, just the last few, but after installing ClamXav, I noticed that my free memory would be zero in the morning (after having run a full scan at 0200). I have a 2011 iMac with 16 GB RAM. Posted on their forum and got some useful links, not the least of which suggested that disk I/O operations, seems even just a big "read" task (such as an AV scan) can consume free memory. Which seems odd.

Using Bresink's Hardware Monitor, I've been logging memory use. Here's free/inactive during creation of a data DVD using Toast:

Forgot to add that I don't feel my 16GB system should be paging out (to an SSD) when I have 14GB "inactive memory".

Here's the link to a useful article:

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

I just installed Lion, and while running Safari, my MacBook gets really hot, and the fan runs constantly, plus, my ram goes from 4g to 130meg.  My interim fix is to use Chrome.  I am not a tech, I just want it to work with minimal input on my part.  That's why I ditched Microsoft.  Come on Apple, FIX IT!

After 24 hrs of Chrome, I've picked up 1 gig of ram, the fans haven't come on once, and the heat is way down.  Works just like Safari used to.

Hi mightymilk. I'm going to be honest, I haven't read through all 49 pages here but I had a similar problem when I first upgraded to Lion from 10.5.8.

Have you tried a complete reinstall of the OS? A copy NOT from your recovery drive?

I took my macbook pro to a genius bar because I was getting a spinning beach ball constatly and they suggested there may have been a poblem with the install. I had all my data backed up so the genius installed Lion from his own stick, I restored my files and everything worked much much better

Apparently it's possible to get something not writted properly during the install, so your recovery partition will also have this defect.