Photoshop7 and the use of 4 GB RAM

"Larry" wrote in message

Hi,

You could assume that Win+Photoshop uses the first 2 GB RAM.

If you did, you would be wrong.
XP divides the 4gb of virtual address space which 32 bit processors provide into two 2GB chunks. One of these chunks belongs to the operating system. The other chunk belong to the user program. Windows XP is the operating system. Thus, it resides in the upper 2GB of virtual address space. Your program (ie Photoshop) resides in the lower 2GB of virtual address space. The reason that an image can be no larger that 1.7GB is that Photoshop and its other thing take up about 300MB.

So, it might be possible to install a RAM disk, but you can’t make it 2GB in size.
Jim

On Sun, 08 Aug 2004 23:21:11 GMT, "Jim"
wrote:

So, it might be possible to install a RAM disk, but you can’t make it 2GB in size.
Jim

Thanks Jim!
Could anyone please help clear this out more for me?

XP says it has 3,5 GB memory (Control Panel, System).
I have 4 GB RAM on the mb.
I have given PS 100% of the available RAM, = 1777MB.

So, PS app+working space has got roughly 2 GB.
(Upper? From RAM 1,5 to RAM 3,5?)
And WinXP sure has taken some RAM.
(Lower? From RAM 0 to RAM 1,5?)

Given this, is there a possibility to use the 0,5 GB on mb which obviously XP can’t use?
IF you would like to create a Ramdisk, how big could it be without eating RAM from
The 1777MB given to PS?

(I guess the obvious answer to this is: just do it and test out!
OK, I will, when I have figured out how to create a ramdisk… 🙂

/Larry

"Larry" wrote in message

On Sun, 08 Aug 2004 23:21:11 GMT, "Jim"
wrote:

So, it might be possible to install a RAM disk, but you can’t make it 2GB in size.
Jim

Thanks Jim!
Could anyone please help clear this out more for me?

XP says it has 3,5 GB memory (Control Panel, System).
I have 4 GB RAM on the mb.
I have given PS 100% of the available RAM, = 1777MB.

That’s a mistake. The OS has memory requirements in the first 2GB. Keep it at 75% or less.

And your ramdisk idea… a thousand others have been there, done that. Royal waste of memory, not to mention time.

Rick

On Mon, 9 Aug 2004 01:21:11 -0700, "Rick"
wrote:

"Larry" wrote in message

On Sun, 08 Aug 2004 23:21:11 GMT, "Jim"
wrote:

So, it might be possible to install a RAM disk, but you can’t make it 2GB in size.
Jim

Thanks Jim!
Could anyone please help clear this out more for me?

XP says it has 3,5 GB memory (Control Panel, System).
I have 4 GB RAM on the mb.
I have given PS 100% of the available RAM, = 1777MB.

That’s a mistake. The OS has memory requirements in the first 2GB. Keep it at 75% or less.

Hi Rick,

Hm, why would PS allow you to assign 100% if that never
should happen?

And, 75% regardless actual amount? In this case, to leave 25% to OS is to give 444 MB to OS. Doesn’t that seem to be a lot?

And, "OS in first 2 GB", "PS in upper 2 Gb","OS in lower 2 GB"… I get a little bit confused..what is using what…?

And your ramdisk idea… a thousand others have been there, done that. Royal waste of memory, not to mention time.

Hm,
I checked the messages in alt.graphics.photoshop (since nov 2001) and comp.graphics.apps.photoshop (since jan 1997)
and of those who had an opinion on Ramdisks there were 10 in favour and 4 (5 including you) that did not think they were useful.
Couldn’t a Ramdisk help use the extra 0,5 GB that XP doesn’t recognize…
Would you like to be a bit more specific about the royal waste? 🙂
/Larry

"Larry" wrote in message

On Mon, 9 Aug 2004 01:21:11 -0700, "Rick"
wrote:

"Larry" wrote in message

On Sun, 08 Aug 2004 23:21:11 GMT, "Jim"
wrote:

So, it might be possible to install a RAM disk, but you can’t make it 2GB in size.
Jim

Thanks Jim!
Could anyone please help clear this out more for me?

XP says it has 3,5 GB memory (Control Panel, System).
I have 4 GB RAM on the mb.
I have given PS 100% of the available RAM, = 1777MB.

That’s a mistake. The OS has memory requirements in the first 2GB. Keep it at 75% or less.

Hi Rick,

Hm, why would PS allow you to assign 100% if that never
should happen?

With any luck Mr. Cox will chime in with a more complete (or more accurate) answer, but my understanding is that PS will not use 100% of available memory even when it’s told to, and specifying a number close to 100% is asking for a major performance hit, if not worse.

And, 75% regardless actual amount? In this case, to leave 25% to OS is to give 444 MB to OS. Doesn’t that seem to be a lot?

Depends what else is being run on the system. But the point is, Windows does need a certain amount of that 2GB user
space.

And, "OS in first 2 GB", "PS in upper 2 Gb","OS in lower 2 GB"… I get a little bit confused..what is using what…?

And your ramdisk idea… a thousand others have been there, done that. Royal waste of memory, not to mention time.

Hm,
I checked the messages in alt.graphics.photoshop (since nov 2001) and comp.graphics.apps.photoshop (since jan 1997)
and of those who had an opinion on Ramdisks there were 10 in favour and 4 (5 including you) that did not think they were useful.
Couldn’t a Ramdisk help use the extra 0,5 GB that XP doesn’t recognize…
Would you like to be a bit more specific about the royal waste? 🙂

Well, first of all you can disregard messages before 2000, because WinNT/2K/XP/2K3 work very differently than
earlier Windows versions. Ramdisks were useful in some
cases in Win9x, but they’re redundant in NT and later
OS’s. Not only are they redundant, invariably they cause a decrease in system performace. Try it and see.

Rick

In article <HzyRc.3617$>,
Jim wrote:

"Larry" wrote in message

Hi,

You could assume that Win+Photoshop uses the first 2 GB RAM.

If you did, you would be wrong.
XP divides the 4gb of virtual address space which 32 bit processors provide into two 2GB chunks. One of these chunks belongs to the operating system. The other chunk belong to the user program. Windows XP is the operating system. Thus, it resides in the upper 2GB of virtual address space. Your program (ie Photoshop) resides in the lower 2GB of virtual address space.

I think this confuses the physical (real) memory with the layout of the address space that each and every process sees.

Any 32bit XP machine, even if it only has 256MB real memory EVERY process thinks it has it’s won a 4GB virtual address space. The pagefile is used to hold the pages that haven’t been used recently. In XP this is 2GB for the application and 2GB for the OS.

If the OP started several copies of PS and looked at the virtual memory usage he would find that each was using lots of memory, in total more memory than the physical memory.

I’ve never played with PS on a machine with this much memory and I think a ramdisk is a mistake, but if PS can’t use all the memory the ramdisk would be a good use for the extra.

It also comes down to what is the best way to spend the money. Very high speed disks (10k scsi) would be my priority. Memory in excess of what the application needs is wasted. A ramdisk only benefits the application that uses it, fast disks speed up everything.

To know what your money is getting you, you need to learn to use Performance Manager (perfmon.exe) to find out how to tune a machine dedicated to PS.

The reason that an image can be no larger that 1.7GB is that Photoshop and its other thing take up about 300MB.

So, it might be possible to install a RAM disk, but you can’t make it 2GB in size.
Jim

—
Al Dykes
———–
adykes at p a n i x . c o m

"Al Dykes" wrote in message

I think this confuses the physical (real) memory with the layout of the address space that each and every process sees.

Any 32bit XP machine, even if it only has 256MB real memory EVERY process thinks it has it’s won a 4GB virtual address space. The pagefile is used to hold the pages that haven’t been used recently. In XP this is 2GB for the application and 2GB for the OS.

If the OP started several copies of PS and looked at the virtual memory usage he would find that each was using lots of memory, in total more memory than the physical memory.

This is what I meant by my first response. If it didn’t read that way, it is my mistake.
Jim