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arn

macrumors god
Staff member
Apr 9, 2001
16,362
5,794
Based on the image shown, the article is completely wrong. The OS is clearly seeing 8 GB, but the load on the system is such that only about 1/2 that is currently being used. Until swap goes > 0, this is simply a matter of not throwing enough at the system to get it to work hard. The fact that used and free are both approximately 4 GB is completely coincidental.

See this http://images.macrumors.com/article/2008/10/24/170020-activity_monitor_parallels.jpg

I didn't do the testing myself, but both Parallels were set for 2GB of RAM. There was also some Photoshop testing which showed similar results.

If you suggest a better way to test, I can try to pass it along.

arn
 

scheming

macrumors member
Mar 15, 2005
74
40
8GB sure to come soon

I'm sure that support for 8GB is sure to come soon. I speak from optimism, but if it is not a software update (which it will likely NOT be), it should be available in Snow Leopard. I have had no issues with my MacBook Pro (Late 2008) and only bought the base model, 2.4GHz 2GB RAM. It is still plenty fast and dependable but I would love to put 8GB in here just because.
 

dal20402

macrumors 6502
Apr 24, 2006
290
0
6gb?

Santa Rosa MBPs choke on 8GB as well. They recognize the 8GB, but get very, very slow if your real RAM usage exceeds 4GB.

But they work just fine with 6GB. Would iFixit be willing to test their new MBP with 6GB and see if it works?

And for the posters saying "why would you need more than 4GB?" ... not everyone just surfs the web and looks at pretty photos. Whenever I'm virtualizing Vista and running InDesign and Photoshop at the same time, I start swapping on my 4GB old-style Penryn MBP.

(My 4GB DIMM for a total of 6GB is in the mail. :D :D )
 

bobrik

macrumors member
Apr 13, 2007
70
0
Prague, Czech Republic
I'd like to see a poll of users who Need 8GB as opposed to 4GB :)

I think that people (developers) who need to run more than 1 virtual machine at a time might hit the 4GB limit easily (i.e. if testing some client-server setup with some VMs being clients and some servers. But I did not yet need it :)). Also note that it's not only about the sum of RAM consumed by all apps - free RAM will always boost performance as the OS will use it to cache disk I/O (think of SSD, but thousands times faster).
 

spill

macrumors newbie
Aug 29, 2007
6
0
Having been assigned an SR based mbp at my last job for java development, I was eagerly awaiting the new mbp for a personal purchase for more of the same.

I guess I am in that 2-5% quotient. A shame.... had a chance to fondle the new mbp at a local store the other day. Everything's great (including access to the hard drive for end-user replacement finally). But a 4GB hard limit on ram at this point in time kind of knocks it out of contention for me, especially with other more capable alternatives out there.

And even if a linux os reports more usable ram than OSX does, how does that matter unless you're going to be running linux until apple decides to "unlock" the full potential of this machine?

The search continues...
 

unkle77

macrumors member
Mar 21, 2008
58
1
PDX, Oregon
i sincerely believe that this limitation on RAM is purely from an OSX point of view. i am sure that once snow leopard comes a long that the full 8 GB ram will be usable.

if someone would be so kind as to load Linux w/ 8 GB ram, that would solve a lot of the nonsense posting that will soon fill these pages...
 

insideo

macrumors newbie
Oct 24, 2008
3
0
See this http://images.macrumors.com/article/2008/10/24/170020-activity_monitor_parallels.jpg

I didn't do the testing myself, but both Parallels were set for 2GB of RAM. There was also some Photoshop testing which showed similar results.

If you suggest a better way to test, I can try to pass it along.

arn

Off the top of my head, something like this:

http://www.theshore.net/~caker/uml/patches/utils/eatmem.c

I had to comment out line 21 (#include <malloc.h>) to get it to compile on a mac...

Make sure developer tools are installed and compile with:

gcc eatmem.c -o eatmem

Then run (several times):

./eatmem 1G

Check activity monitor to be sure the "Real Memory" column is actually large... when finished, do a "killall eatmem" to free it up again. I tried this on a Mac Pro with 10GB RAM, and it will consume it all if you run enough instances.

If this test doesn't use all the ram on an 8GB laptop, then perhaps there's a problem. Until then, I'm not convinced.
 

Krona

macrumors newbie
Oct 24, 2008
1
0
Parallels isn't 64-bit

Some more details on the attempted test would be useful. It looks like you tried to run a couple instances of Parallels and found that you weren't using much memory; this isn't very surprising though since you're not doing anything useful in them and Parallels itself isn't 64-bit (so a single instance can't go above the 4GB limit). So what was meant by "it acted as if there wasn't more than 4GB?"; does this mean that Parallels complained in some manner when you tried to launch still more copies of Parallels?

Running the code from the previous post would be a better idea. As far as I can tell from the Activity Monitor, it looks like 8GB will just work.
 

eric_n_dfw

macrumors 68000
Jan 2, 2002
1,517
59
DFW, TX, USA
I need > 4GB

Doing large J2EE web application development, I run into paging on my 3GB MBP (older one that can't use 4GB) and my 4GB Dell (running Ubuntu or XP) all of the time.

What I'm doing simultaneously that drives that need:
1. Opening multiple, large IntelliJ and/or Eclipse projects: about 512MB to 1GB used per
2. Running our app on JBoss with 1GB to 2GB heap space: min 1.5GB used
3. Running a 2nd Tomcat app server to test: probably about 256 - 512 MB used
4. Compiling in Maven2: 1.25GB when running automated tests probably 768MB for incremental builds
5. Entourage: hundreds of MB
6. Firefox 3: as much as it can grab!

Then add in the occasional OmniGraphel, Excel, Word or other office app and you are paging like a madman. (Not to mention if I have to fire up VMWare to test with IE or run one of our company's Win32 only office applications)
 

dal20402

macrumors 6502
Apr 24, 2006
290
0
As far as I can tell from the Activity Monitor, it looks like 8GB will just work.

Activity Monitor is not always a reliable indicator of what's happening.

On Santa Rosa MBPs, everything looks fine in Activity Monitor if you install 8GB of RAM. But when your usage exceeds 4GB, the machine slows down so much that it's unusable.

On Merom/Napa MBPs, everything looks fine in Activity Monitor if you install 4GB of RAM. But you'll find that you start swapping when your real usage exceeds about 3.25GB.

Given the problems that Santa Rosa MBPs have with 8GB, I'm inclined to believe these new unibody MBPs also have problems with 8GB. What I want to find out is if, like SR MBPs, the unibody MBPs work with 6GB.

eric_n_dfw said:
I run into paging

You don't say... you need a 16GB Mac Pro for that kind of workload! (Or to quit and restart Entourage and Firefox from time to time...)
 

mariusaz

macrumors member
May 10, 2007
42
0
Operating System

It would be interesting to see if this is an Operating System limitation and whether or not you'd have the same results booted into Windows. If so, maybe it's only a driver issue. (Although I have not read into the details)
 

commander.data

macrumors 65816
Nov 10, 2006
1,056
183
As others have said it's probably something to do with the current EFI version. 4GB DDR3 SODIMMs aren't common right now so Apple probably hasn't validated the EFI to make sure it's compatible with memory that's on the market. As such, support for RAM greater than 4GB is not enabled to ensure stability. As more 4GB SODIMMs come to market Apple will probably validate and enable 8GB support. Although it wouldn't surprise me if they'll save 8GB support in the 9400M chipset for a later refresh and not enable it on current models.

Another possibility is that the 9400M chipset supports 8GB, but seeing that Apple got first dibs and launched their products before nVidia themselves launched the 9400M chipset for OEMs, the versions that Apple uses may be early revisions that have issues with more than 4GB of RAM which is why it's disabled.
 

Neuro

macrumors regular
Jun 15, 2003
209
2
London
I'm intrigued that so many people have marked this story as positive! What can possibly be great about having less ram than possible? lol. Bizarre....
 

Di9it8

macrumors regular
Jan 10, 2006
197
0
I'd like to see a poll of users who Need 8GB as opposed to 4GB :)

I have my MBP as my main working machine, using 3d rendering so I would be very happy to be able to access 8GB on a fairly regular basis.
Thats assuming that the programmes will use the extra RAM ;)
 

Bubba Satori

Suspended
Feb 15, 2008
4,726
3,756
B'ham
If Linux can see and use 8GB then apple can release a software update that makes the 8GB accessible. If Linux can not see it there may be some hardware (address line) limit that has nothing to do with the chips but has to do with the motherboard design. So if it is only software then Apple can fix it for the existing models.

Given there are Dell laptops with 8GB I presume it is not the CPU. I would guess that the XEON driver allows addressing more RAM and the Core2Duo driver does not. This can be fixed with a software update, but might have to wait for Snow Leopard when making use of the RAM will be easier. With Leopard unless the app is 64bit no ram above 4GB can be used. With Snow Leopard the OS gets relocated so that this is not an issue. With the Mac Pro you can not get all the RAM contiguous as the OS takes a chunk at the 4GB boundary for itself.


The Dell Precision 6400 will take 16GB. It's not a Xeon chip. The dell has four memory slots and will take 4GB sticks.
 

ifixit

Guest
Oct 24, 2008
6
0
Further 8 GB Tests

We did some more testing and found some interesting things. We have not succeeded to go beyond the 4GB limit with any OS X GUI app. With a C app (eatmem) that does not use Apple's APIs, we were able to allocate 8 GB and have it reported in Activity Monitor (and top).

The C app was able to allocate up to 8 GB without paging to disk. However, OS X is not happy running at or above the 4 GB limit. Performance is very erratic, and we crashed OS X and Parallels multiple times.

8_gb_ram.png

8 GB allocated, the system crashed shortly thereafter.

Interestingly, when we booted Ubuntu on the machine it only reported 3 GB memory total. We don't have an explanation for that.

Overall, our testing showed that the system is unstable at 8 GB of RAM. Parallels takes forever to load, even when using < 4 GB of total memory. The OS doesn't seem to page out properly, but we didn't spend a lot of time trying to track this down.

We then yanked a chip to do a comparison with 4 GB. With a single 4 GB chip, everything seems happy.

We then added a 1 GB chip for 5 GB total. We were able to get GUI apps to use all 5 GB and the system hasn't crashed on us yet. It will take more testing to determine how stable this configuration is.

We suspect that this testing implies a two things:
1) The hardware can handle a 4 GB chip without any problem
2) There are OS-level limitations with 8 GB RAM on these systems.

Luke Soules
iFixit Labs
 

dolphin842

macrumors 65816
Jul 14, 2004
1,172
29
Given that Safari never gives up RAM, I might need 8 GB to use it without quitting for more than 2 days :p

Back on topic... thanks Luke for your testing!
 

840quadra

Moderator
Staff member
Feb 1, 2005
9,253
5,966
Twin Cities Minnesota
Perhaps this artificial ceiling is something that will be resolved with 10.5.6 . Remember there are already a few bugs found in the current version of 10.5.5 that shipped with the new MacBook pro models. One of the biggest being the lack of indication for supporting 802.11n .

Perhaps the next build will address this, and or it will be something for Snow Leopard.

We did some more testing and found [...]

Luke Soules
iFixit Labs

Thanks for your testing, and continued efforts!

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