Re: [Gimp-user] Tweaking performance

On 11/15/2011 04:21 PM, jfrazierjr nc rr com wrote:
Ok.. so I am working on a large image and want to see if I can increase performance speed any.  I knew things 
would be slow, but was hoping I could get a bit better than what I currently have.  The image will be a 
map(as in fantasy world map) I want to print(will scale down for web version to .jpeg), 36x24 inches @300 
DPI, so 10800x7200 resolution(ie, poster print size).

I have a fresh install of Linux Mint 11 on a laptop which is about two years old.  I don't remember the full PC specs 
off the top of my head though but is was a mid-high end range gaming Laptop(so probably in the top 70%-80% of 
"best" available laptop hardware specs at the time of purchase).

What I do know off the top of my head:

multiple partitions
20GB Linux swap
Mint installed to single partition 190GB out of the entire HD's 500GB(both /home(location of the xcf file) 
and /tmp are on the same partition.
6GB RAM (8GB max)
multiple USB 2 ports
1 eSATA port
Wacom bamboo tablet
video card is (I BELIEVE) a GTX 200M

built from source (git) as of umm... Friday night(or so)
Currently, I have my tile-cache size set to 5GB

I typically have 3-6 chrome browser windows open and perhaps 1-2 open directory folders, but other than that, 
there are few applications running other than those(occasionally Thunderbird).

Currently, the file opens up around 4.5 GB in memory, with spikes up to 10GB so far that I have seen.  I have 
about 15 layers so far, with about half of those using a layer mask.   Most of the layers are transparent at 
this point, with a few being full color with layer masks to define geological features(grassy plains, desert, 

I have yet to add the additional layers needed to represent mountains and forests(at least 4 layers each, 
line-work, color, highlights, and lowlights, so min 8 layers for that) as well as several layers for some 
type of desert texture, labels(4-5 layers), and likely a compass rose and a Cartouche of some type(likely 4-6 
layers for shape/color as well as 2-4 text sections).  So all together, this will likely encompass around 
35-40 layers when completed(if I can get that far!!!).

So, are there any suggestions you guys might make?  As slow as it is currently, I don't know if I will even 
be able to get anywhere near to the number of layers I expect to need.  Should I just give up on such a large 
image and reduce the scale or is there any additional tweaks I can make?  Will adding a eSATA or USB2 drive 
to hold the the /tmp help at all?  I this was a desktop, I could easily just slap another Harddrive(or two) 
in and have different read/writes working in parallel(ie, /tmp and swap on a separate physical drive), but I 
don't have that luxury with a Laptop... Would adding an additional 2GB make a noticeable(as in very 
noticeable) difference?

I appreciate any suggestions you guys might have.  Please let me know if there is any additional 
information(ie, L2 Cache, Processor, etc) and I can get that info later tonight.... though of course those 
are things I cannot change...


this is going to be tough!
So much layers, especially with masks and with that resolution is way beyond the specs of even a new mid-level desktop computer, as far as I can tell.

In any case I will suggest that you utilize the full RAM capacity of your motherboard. Then the machine will swap 2GB less, which will make some difference at least until you reach certain level.

I think USB2 will be horribly slow, so no point of adding such drive. And, I hope that somebody will correct me if I am wrong, but I don't think that GIMP uses /tmp that much if at all. What you really need is more RAM and a fast drive for the swap partition.

Apart from this you could split the file in several separate files, that will hold several logically grouped layers each (I presume that you don't have to work simultaneously on all of the layers). This way you can speed things drastically. In each of these files you could include one (or few layers) that represent all of the other layers (from the other files), but merged, with layer masks applied, etc. - just as a preview of the other parts of the whole image... i hope you get the idea despite my explanation. This way you will work with only say 5 - 10 layers + one or few 'preview' layers, that represent the rest 30 layers.

Good luck,
Petar Kostov

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