LR4 and WinXP

[Farmer]

LR4 wouldn't crash due to running out of memory - 1.9GB is just the RAM being used - memory management would deal with it using however much it needed in each process, but you'd be swapping out to disk.  Yes, each process would be more limited under 32bit OS, but overall the program would deal with it if written to do so.

[dreed]

LR4 wouldn't crash due to running out of memory - 1.9GB is just the RAM being used - memory management would deal with it using however much it needed in each process, but you'd be swapping out to disk.  Yes, each process would be more limited under 32bit OS, but overall the program would deal with it if written to do so.

I think you misunderstand.
Windows XP has a limit on 2GB for a process's address space unless you do something special to make it 3GB and also compile the application in a special way.

So even if I have a PC with 4GB of RAM, no application running under Windows XP can ever have 3.5GB of allocated address space.

[RFPhotography]

...... also compile the application in a special way.

Huh?  If the application can access more than 2GB of RAM then turning on the 3 gig switch in the boot.ini menu is all that's required unless, like Photoshop, there's a preference setting for how much memory to use and if that's set to less than 2GB it can be increased.  I've never read or heard anything else related to flipping that switch.

So even if I have a PC with 4GB of RAM, no application running under Windows XP can ever have 3.5GB of allocated address space.

But as Farmer pointed out you're talking only about physical memory.  If there's insufficient physical memory (RAM) then applications use virtual memory (i.e., the scratch disk) as a substitute.  It's not as efficient but it works.  This is why, for users of applications such as Photoshop and Lightroom that can be resource intensive the suggestion is to have a large amount of free disk space for the applications to use as virtual memory.  A number of people have a separate hard drive installed that is dedicated as just a scratch disk.

[Farmer]

I think you misunderstand.
Windows XP has a limit on 2GB for a process's address space unless you do something special to make it 3GB and also compile the application in a special way.

So even if I have a PC with 4GB of RAM, no application running under Windows XP can ever have 3.5GB of allocated address space.

It's a process limitation, not application (which can run many processes).  A 32bit PS or LR can already deal with a 6GB image file, for example.  So you wouldn't run out of memory just because your current version is reaching near to 2GB on a particular process.

Even assuming an app wasn't compiled to be Large-Address-Aware, it would still deal with larger amounts of data without crashing due to running out of memory (unless it was horribly written!).  If it was compiled to be Large-Address-Aware then each process could use more memory if the 3GB flag is set (up to 3GB - the 3.5GB frequently quoted is another limitation relating to video memory mapping and refers only to physical RAM and even that is not always correct - smaller GPUs will see that number increase toward 4GB and this is because the x32 versions of Windows can not address memory above 4GB range eventhough a PAE set system and PAE aware drivers can do so).

[barryfitzgerald]

I updated my pc to a quad core last year the whole lot new drives everything and Win 7 64bit too (obviously)
I can't say I'll be using that 16Gb of ram I put in (but it was cheap DDR3 is dirt cheap)

I've run plenty of budget builds on 4Gb ram (Win 7 64bit again) 8Gb offer some gains for heavy hitters above that not really any improvement but at least you won't be crying out for more ram.

But I could easily have just done an update to my older build and used XP. XP is still decent, granted it's getting on a bit but a lot of folks like it. I would say to people Win 7 is actually very good it's no Vista so don't be scared of it or upgrading. But still I'd expect the OS to be around for quite some time XP was (after SP2) well liked.

[Schewe]

...XP is still decent, granted it's getting on a bit but a lot of folks like it. I would say to people Win 7 is actually very good it's no Vista so don't be scared of it or upgrading. But still I'd expect the OS to be around for quite some time XP was (after SP2) well liked.

But the fact is, LR 4 won't be running on XP. You can read what Tom Hogarty, the product manager said (and the myriad of comments) on the Lightroom Journal. He also noted that Mac support is being limited to 64-bit Mac systems and 10.6.6.

But unlike Adobe's reversal on Suite upgrades which was a policy decision not based on technical limitations, Adobe won't be changing their minds about XP. You either upgrade your OS to run LR4 or you don't run LR4 regardless of which platform you are on. This really ain't a Windows thing here...

[dreed]

Huh?  If the application can access more than 2GB of RAM then turning on the 3 gig switch in the boot.ini menu is all that's required unless, like Photoshop, there's a preference setting for how much memory to use and if that's set to less than 2GB it can be increased.  I've never read or heard anything else related to flipping that switch.

But as Farmer pointed out you're talking only about physical memory.  If there's insufficient physical memory (RAM) then applications use virtual memory (i.e., the scratch disk) as a substitute.  It's not as efficient but it works.  This is why, for users of applications such as Photoshop and Lightroom that can be resource intensive the suggestion is to have a large amount of free disk space for the applications to use as virtual memory.  A number of people have a separate hard drive installed that is dedicated as just a scratch disk.

No, I'm not.

A process's address space refers to how much memory it can address.

Scratch disks are not virtual memory.

[RFPhotography]

No, I'm not.

Not sure what you're referring to.

A process's address space refers to how much memory it can address.

I understand that.  But commercial software either is or isn't able to use more than 2GB of RAM.  If it is, flipping the 3 gig switch is all that's required.  If it isn't, then that won't work.  But recompiling a piece of commercial software isn't something that the user does.

Scratch disks are not virtual memory.

Yes, technically true.  OK, substitute scratch disk for virtual memory in my previous comment.  Either way the point is the same.  The Photoshop scratch disk is a form of virtual memory.