Hi , can anyone tell me what the limit is on Gimp's ability to allocate virtual and real memory or storage. Are there published guidelines?
I am trying to do a 24" X 18" at 300dpi complex image ( a mapping project ). My swap tile in Gimp is set at 4095 MB. I have 8GB of storage on my win 7 system. x64 dual processor E8400 (not the greatest but still quite capable). Running Gimp 2.6.11 . I can see on windows task manager that my job is running at over 3 GB and running at 50 %. During that time I can do other tasks while Gimp is doing its thing, so it seems a Gimp problem as all other win tasks keeps running.
Watching the task manager my job aborts when the allocation exceeds 4 GB. (in some cases)
I thought that Gimp would swap out this memory tile when it reached this limit and place this memory block in virtual storage. I have a 1 TB disk with roughly 600G free .
I also have aborts with messages such as "Unable to allocate X amount of storage"
I have the same problems on Ubuntu so again I think this a Gimp, not an operating system problem. Although it runs a bit better on Ubuntu. Probably due to less overheads. Note that I have left some operations , eg "stroke a selection" run for 20- 30 minutes to complete.
I have tried different Gimp tile sizes, etc , different Windows swap file settings.
So is there a limit that can use to plan some of my stuff or is there a way around this by tiling the image / job?

Maybe running a more recent version of gimp AND AT 64BIT will help

For sure gimp at 32 bit can't do nothing with 8GB ram, as all 32bit programs may use no more than 2 (or 3? now i am not sure , anyway much, much less then 8 )

And here swap can't help, swap is used when RAM is insufficient and is really slow...sure better very, very slow then a crash for insufficient RAM but no way you can make it faster if is using the swap space because insufficient ram

If you have a 32bit version of Gimp, then this is normal, a 32bit program can't work with more than 4GB or memory.

As I understand it the swap tile *cache* in Gimp is actually how much RAM or swap it will take for the tiles (the rest is kept on disk), if you are using a 32-bit version, giving it more than 3GB is asking for trouble since that will make Gimp try to use more than 4G or address space (tile cache, plus program code, plus other data).

Hi PC and Ofnuts , Thanks for the replies. I am running 2.6.11 I686 which I thought was a x64 version.
I have searched the net to see if 2.6.11 i686 is not a 64 bit version but I cant find any definitive statements to that fact. I seem to remember that the 32 bit version would not let you define the tile segment as more than 2 G. However I am not sure.
Ofnuts how can I find out if I have a 32 bit or 64 bit version installed or a 64 bit version running in 32 bit mode?
I was not going to switch to 2.8 for another month or two.
Perhaps someone on this forum can confirm that you can run a complex task such as 24X18 " 300 dpi image manipulations on gimp 2.8

I remember from some time ago, how Gimp slows down with even simple operations once you start adding layers.

This was making the frames for count-down timer by duplicating a layer (the hand) and rotating. After very few of these operations, it slows to a crawl.

Recreating that on a newer faster machine (3 GHz quad core, 4 GB mem) and gimp 2.8, much the same. I upped the tile cache size to 2 GB.

Starting with a base like this, http://i.imgur.com/Td6qo.jpg
nowhere near as large as OP's but 3000x3000 pix
Then added a layer with a "hand" at 12-o'clock, duplicated and rotated 30 deg. The rotation time for subsequent layers is
layer 1 - 16 seconds
layer 2 - 33 seconds
layer 3 - 1 minute
layer 4 - 1 min 57 sec
layer 5 - 3 min 36 sec
layer 6 - 7 min 30 sec
So exactly the same operation doubles for each new layer. I am not a masochist. At this stage system memory was almost used up and even rendering the "hand" slowed to a crawl, stopped here.
screenshot at this stage. http://i.imgur.com/IdrJK.jpg

Similar projects recently with large images and several layers and the way I go is to create the layers individually, do whatever editing & save them. Then to finish-up, start afresh and import as layers. That way you don't get so many of the Gimp overheads.

I have installed Partha's 2.8.1 64 bit windows and retried the operation. my xcf from my 2.6.11 took almost 10 minutes to load. I am currently doing a shaped blend and it has been running for 1.5 hours and only half way through.( I hope I have the gradient around the right way, Ha Ha) However it is not crashing as it was with 2.6.11. I shall do some experiments with this . Rich, I might try your option of doing single tasks and saving and re-import as layers.

1.5 hrs., wow

The XCF is over 130MB so any operation on that will be very cpu intensive. Interestingly, although I have 2 cp's set as available, it appears from windows task manager that only 1 cp is doing the work. Whereas before with 2.6.11 both cp's were involved.