Lion - Memory Usage Problems

mightymilk wrote:

With Snow Leopard, you could hold the "3" and "2" key during Startup to launch in 32-bit Mode.

Same thing on Lion, see my upper post.

Thank you.... will try this now and keep running the kernel at 32 bit to see how this helps.

Michelasso wrote:

The problem is that it seems the OS X Lion memory management system is screwed. Otherwise it wouldn't explain why, when still having 1GB of free memory (mostly inactvie) sometimes it starts paging out like crazy making in my case a swap area of 1.2GB or so.

What do you mean by "free memory (mostly inactvie)"? Free & inactive memory are two different things.

Also, what do you mean by "a swap area of 1.2GB or so"? Which (if any) numbers in Activity Monitor are you getting this from?

Please remember that Activity Monitor can't tell you how inactive memory is apportioned to different processes or why it isn't being released to the free memory pool. A process may have used code or data in RAM that it is not currently using but might use again. The OS will try to retain it as part of the inactive memory footprint of the process for as long as it might be useful.

That means that for say Safari, it isn't just the currently open web pages that contribute to its inactive memory use, but also other web pages that have been opened since the app was launched. That includes the code & data used by ads, browser plug-ins, Javascripts, & any other content a web page might contain. Neither Activity Monitor nor just looking at the visible content of the web pages will tell you how much memory a web page actually uses. You can get a rough idea of this by looking at its source code ("View Source" for Safari), but unless you are familiar with Javascript & other web page constructs & do a careful analysis, even that will be only a very rough indicator. Pages that contain ads or complex Javascripts can be particularly deceptive in this respect since they often load a lot of stuff that isn't visible & may not even be used unless you click on them.

So for some of you, what looks like Safari using excessive memory might instead be the result of viewing some resource-hungry web pages, even if they are not currently being displayed. Also, don't overlook the possibility of browser plugins or extensions that are not fully compatible with Lion, poorly written Javascripts, & so on.

R C-R wrote:

Please remember that Activity Monitor can't tell you how inactive memory is apportioned to different processes or why it isn't being released to the free memory pool. A process may have used code or data in RAM that it is not currently using but might use again. The OS will try to retain it as part of the inactive memory footprint of the process for as long as it might be useful.

What you say is correct, but even with ALL applications closed, i have A LOT of inactive memory on 64bit kernel. That doesen't happen in 32bit kernel mode.

I re-booted into 32bit mode, continued watching a movie with DVD Player (and just Mail open, no Safari) and I'm watching my "Inactive" memory climb and "Free" memory decrease all at about 1mb/s. This seems crazy.

The data from the DVD is being retained in Inactive memory just in case it's needed. So long as this is not hurting overall system performance, it's working as William K so eloquently described earlier.

William Kucharski wrote:

So are all of you seeing pinwheels or just objecting to the numbers in Activity Monitor?

For this discussion to be helpful to anyone, this is something everyone must make clear in their posts.

High memory use as shown by Activity Monitor is not by itself a symptom of any problem. Despite what some think, an app like Safari may use many GB's of available RAM to support its new features. That is what RAM is for. It would be a problem if it did not use it.

OTOH, if high memory use is accompanied by performance issues, you obviously do have a problem, but keep in mind that it may not be caused by high memory use. That could be a symptom of the real cause. That cause may be something that only Apple can fix, but it might also be something users can fix.

Either way, the more info you can provide the easier it will be to figure out what the appropriate remedy is for you. Don't assume that will be the same thing for everyone. It almost certainly won't be.

R C-R wrote:

Michelasso wrote:

The problem is that it seems the OS X Lion memory management system is screwed. Otherwise it wouldn't explain why, when still having 1GB of free memory (mostly inactvie) sometimes it starts paging out like crazy making in my case a swap area of 1.2GB or so.

What do you mean by "free memory (mostly inactvie)"? Free & inactive memory are two different things.

Also, what do you mean by "a swap area of 1.2GB or so"? Which (if any) numbers in Activity Monitor are you getting this from?

I am using mostly iStat Menus to monitor my resources. So I see Free memory plus Inactive memory as "available" memory. Let me rephrase it: still having 1GB of available memory (mostly inactive) Lion starts paging like crazy.

iStat Menus also shows which is the size of the swap memory really paged out. As I wrote sometime suddendly it goes from 0 to 1.2GB just doing nearly nothing and still having plenty of available memory.

It's not the issue how the inactive memory has been allocated. On which you are correct anyway. My idea was that the kernel, once it is low in free memory, first frees memory from the inactive memory list and only if none is available it starts paging out. That doesn't seem to be the case. Instead Lion seems to page out the inactive memory and only then it reallocates to the requesting processes the freed memory. Which, in my modest opinion is either a bug or a very dumb decision.

The inactive memory should be a sort of cache for the pages on the disk that have already been read.If a process requests a page that had already been allocated and it is present in the inactve memory it reallocates it from there. Otherwise from the free memory. If the free memory is below the low water mark, OS X should free a bunch of pages from the inactive memory. I have been monitoring the memory usage in the last few days and as far as I could check none of that happened. I also disabled the virtual memory manager (dynamic_pager) for testing, and with 3GB of RAM OS X was running happy even pushing the system much more than what I do on normal usage, where I still get high paging activity (I started a Win7 64 bit virtual machine on top of my regular applications). Well, the CPU suffered obviously, but in terms of memory it was just fine.

In other words I have no idea what Apple did with Lion. I just know that in SL I rarely saw paging activity, in Lion it appears to be the norm.

ayrtonoc wrote:

What you say is correct, but even with ALL applications closed, i have A LOT of inactive memory on 64bit kernel. That doesen't happen in 32bit kernel mode.

Why does this concern you? Even when all user-launched processes have been quit, system processes continue to run. If there is no demand for active memory from other processes, there is no reason to release the inactive memory they have used.

As William Kucharski said, free memory is (at least in one sense) wasted memory -- it isn't being used for anything. RAM is a resource meant to be used. If the OS isn't using it, what is the point of having it?

R C-R wrote:

Why does this concern you?

I thiks that's a VERY LARGE BUG because Michelasso had summarized very well the situation:

"It's not the issue how the inactive memory has been allocated. On which you are correct anyway. My idea was that the kernel, once it is low in free memory, first frees memory from the inactive memory list and only if none is available it starts paging out. That doesn't seem to be the case. Instead Lion seems to page out the inactive memory and only then it reallocates to the requesting processes the freed memory. Which, in my modest opinion is either a bug or a very dumb decision."

So why the system use page file, in 64bit mode, before freeing inactive memory??

Why the 32bit kernel frees that portion of memory before using paging file??

That's the matter!!

And is not related to ANY scientific theory of memory use: is a fault.

mightymilk wrote:

It's important to note, a lot of us are experiencing performance issues.

My personal experience is that after all Free RAM has been used up, the Inactive RAM is not being purged back to the System as needed or to the Applications that need it. I start seeing heavy Page Out activity as a result. That's when my system starts to take a serious performance hit.

Right. That's exactly what I wanted to explain in my previous post.