My 4G RAM Experiment

H

ho72

Weaksauce
Joined
Sep 20, 2005
Messages
119
is not working out.

I borrowed 2 DIMMS (Corsair CMX1024-3200C2)
identical to the ones I already have installed. Now I have a total of 4GB of RAM adorning my PC. I Ghosted my clean XP Pro SP2 install onto my HD for a testbed. I added the /3GB switch to the boot.ini file. Windows reports 3.37GB of RAM. Fine.

I loaded up the Photoshop CS2 demo. It reports 1761MB available @ 100% usage. This is the same amount available with only 2GB of RAM installed in the machine, IIRC. I was expecting to see somewhere in the neighborhood of 2600+MB available to Photoshop. CS2 *knows* that it's there, here's a snip from the PS system info:

Physical processor count: 2
Processor speed: 2210 MHz
Built-in memory: 3454 MB
Free memory: 2988 MB
Memory available to Photoshop: 1761 MB
Memory used by Photoshop: 100 %
Image cache levels: 4

Whassup?
 
OK I've seen this 4gb ram question repeated all over the place over time.

Let me explain:

It is not an OS issue (though some of it may be), it is a mothereboard issue that cannot be resolved (as technically it is not a problem). Some ram is limited by OS and some is used by the AGP aperture, but even if it wasn't you would NOT have 4gb ram registered in windows.

The reason for this is because anywhere between 128mb-1gig of ram is used to "map" the PCI hole (the amount used depends on your motherboard and whether the mapping is discrete or continuos). This is not an error and should happen. I used to have a bookmark explaining the differences as you go up in ram but I can't seem to find it.

[Edit]: I found the paper, a better explanation of the "4gb ram effect" can be found here.
 
OK, I guess I am not making myself or my problem clear.

I don't care that XP doesn't see the full 4G. I don't expect or need it to. What I want is for Photoshop CS2 to recognize the /3GB switch and make more RAM available for itself. CS2 has this capability on a 32bit OS, but so far it has eluded me.

Here is the CS2 System Info from a system similar to mine:
Physical processor count: 2
Processor speed: 2412 MHz
Built-in memory: 3326 MB
Free memory: 2301 MB
Memory available to Photoshop: 2689 MB
Memory used by Photoshop: 55 %
Image cache levels: 6

Here is the same info from my machine:
Physical processor count: 2
Processor speed: 2210 MHz
Built-in memory: 3454 MB
Free memory: 2988 MB
Memory available to Photoshop: 1761 MB
Memory used by Photoshop: 100 %
Image cache levels: 4

Note the difference in the "Memory available to Photoshop" listing. This is what I am trying to correct.

The same scenario is discussed in this thread:

http://www.adobeforums.com/cgi-bin/[email protected]@.3bbca85e/0

My guess is that either CS2 is not recognizing the /3GB switch, or I have not implemented it properly.
 
OK, I rewrote the boot.ini file and now it works--I have 2700MB available to PS @ 100%. Apparently it was user error... :)
 
The improvement factor:

*Time to open 3 images simultaneously for editing (2GB) = 73 seconds
*Time to open the same 3 images simultaneously for editing (4GB) = 35 seconds

Now if I just had a solid state HD for scratch... :)
 
How big are these images? Also can you post some comparisons applying filters, such as the radial blur test that was done here a while ago. Thanks...
 
The images range (on disk) from 140MB to 225MB. Once opened in Photoshop, they occupy over 2GB (due to layers, channels, and masks).

There is no improvement in the Radial Blur test because that does not consume enough memory to be Scratch dependant. However, overall response when manipulating large images is improved, as is working between apps. I often have Photoshop, Freehand/Illustrator, and InDesign open at the same time. I can turn PS loose on a long filter run, say Lens Blur, and switch to another app and continue working without missing a beat. Of course, much of the credit for this goes to the DualCore CPU, but it seems to be snappier since the memory upgrade.
 
I have a 385mb TIFF image that takes roughly 2 minutes to open.

It's a picture of the Orion Nebula, 18000x18000 pixels, 324 000 000 pixels in total.

That picture makes Photoshop take up 700mb of Memory.
 
Borgschulze said:
I have a 385mb TIFF image that takes roughly 2 minutes to open.
It's a picture of the Orion Nebula, 18000x18000 pixels, 324 000 000 pixels in total.
That picture makes Photoshop take up 700mb of Memory.
Click to expand...
If you handle images like that often, you're in serious need of either more RAM or lots of patience.
 
ho72 said:
If you handle images like that often, you're in serious need of either more RAM or lots of patience.
Click to expand...
Zooming and scrolling is no problem, it's just the opening part that takes a little while.
 
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