GIMP Question (Layers and Memory)

[Furuno]

While i'm running GIMP with a large image size (5000x3000 ++), GIMP use a hell amount of memory (1.5 GB ++) and i found that each layer can be as huge as 200 MB even for only a layer filled with black. Making the performance quite slow...

Is there any solution to reduce the memory usage? I haven't experience this amount of memory when doing the same task with Photoshop CS3...

Note : I'm using GIMP 2.4 on Ubuntu 8.04 AMD64 on a computer with 2 GB of RAM...

[SeijiSensei]

One solution I can think of would be to get a USB memory stick, say 4 GB or 8GB in size, and set it up as the swap area on your machine. Here's how:

1) Plug in the stick; it should appear on the desktop as a USB storage device, say /dev/sdd.

2) Format the stick for swap by using "fdisk /dev/sdd" to blow away whatever file systems are there (usually FAT32) and create a single new partition for swap (/dev/sdd1 in this case). Mark it as "LInux swap" (type 82).

Spoiler for fdisk details:

After you run the command "fdisk /dev/sdd" replacing "sdd" with the device identifier for the stick, you'll end up at a "Command" prompt. You can type "m" for help as instructed, but here's a step-by-step guilde:

Command: p
You'll see a display of the partitions on the stick; probably there's only one (/dev/sdd1 in our example), and it's probably formatted as FAT32.

Command: d 1
Delete the existing partition

Command: n
Create a new partition. In the prompts that follow choose "p" for primary and 82 for the file system type (that's the designation for Linux swap).

Command: p
Now you should see one partition that fills the stick marked as Linux swap.

Command: w
Write your changes to the stick.

Command: q
All done.

Then format it with 'mkswap /dev/sdd1'. Next edit the file /etc/fstab and find the line with "swap" as the second parameter. Comment out this line by putting a "#" at the front of the line, then add the line

/dev/sdd1 swap defaults 0 0

to the file and save.

Last step. Type the command "swapoff -a" followed by "swapon -a" and it should start swapping to the stick. When rebooted the OS will use the stick by default.

I haven't done this myself but I've configured additional physical swap partitions, so it shouldn't be any more difficult to use a memory stick.

You'll need to be root to do this either with "sudo" or by enabling the root account In Ubuntu. There's discussions of how to do this online. I hate having to use the sudo mechanism when I have a set of tasks I need to undertake as root as in this example. It's just easier to "su" to the root user.

[Furuno]

Thanks for the instruction! That's a big help for a people new to linux like me...

But... Isn't swapping from flash disk is much slower than swapping from harddisk? Is there any way to adjust GIMP memory usage for each layer?

[SeijiSensei]

I would have thought swapping to a solid-state device like a memory stick would be faster than swapping to a hard drive, but perhaps the data-transfer rate of USB 2.0 is a limiting factor.

Anyway, I decided to see if there was an answer to your original question. I did a search on Google for "gimp linux memory" and discovered that you can adjust the memory usage in Edit > Preferences. If you look at the help file for that screen, you'll see a reference to this page on setting the tile cache. I think that's what you were looking for.

I don't think there's any way to specify memory usage on a per-layer basis though.

Adding another 2 GB of physical memory would obviously also help.

BTW. furuno, this discussion appears in the seventh spot of that Google search. Guess we'll be famous forever now!

[Furuno]

Okay, this is helps! Thank you very much!

P.S. Googled for "gimp layer memory" too and this is the first result...