Re: [Gimp-developer] Ways to improve Gimp 2.9 performance

[Elle Stone <l elle stone gmail com>]

On 2/28/13, Liam R E Quin <liam holoweb net> wrote:

> In the meantime,
> (1) look at what other processes are running - e.g. in "top" you can
> press M (not m) to sort processes by size, and the results can sometimes
> be surprising...

Thanks very much! for the tip on how to sort in top.

> (2) in gimp...
> even with more memory gimp goes faster if you clear the undo history
> frequently. Save snapshots as needed... and then... to do this...
> i) make sure the Undo history dock is visible
> ii) press the Rubbish/Waste/Trash/Clean/Broom icon (it depends on theme)
> at the bottom of the undo history dock to clear the undo history.
> iii) make sure the title or status bar of gimp shows you memory usage,
> and when it grows by more than about 500MBytes, clear the history again.

These are things I haven't been doing, will give it a try.

> Make sure you have the latest driver offered by your Linux distribution;
> the non-free drivers for nvidia and ati cards make a huge difference but
> they ypically need ot be patched slightly by your Linux distribution or
> things may go horribly slwoly and/or wrong (the drivers by default
> overwrite some of the standard X libraries)

I switched to the nonfree nvidia distributed by openSUSE because the
nonfree driver manages the fan better. Do you think the openSUSE
version might be properly patched? I was using nouveaux, could go back
to it.

> Turn off 3d desktop effects, as these can make gimp painting go two,
> three, or more times more slowly (e.g. do not run compiz).

> > *Does it matter how many system fonts are installed?
> Doesn't seem to for me but I have 8G of ram.
> so I have 2,500 fonts installed right now (and many more that are not
> installed).
That's a lot of fonts!

> > 3. Image size, type, precision
> 8-bit grayscale is fastest by far, and usually what I use.
> Avoid transparency (alpha channel) if you don't need it, and flatten a
> single-layer image after any transform operation.
> For some filters you need RGB mode, and then can go back to greyscale
> afterwards (sometimes it's surprising which filters they are - but as
> the filters get ported to GEGL that will probably change)

I need 16-bit precision for working with linear gamma files. I'm
already switching back and forth between grayscale and RGB as needed,
but I wasn't sure if it made much difference. I also wasn't sure if
16f vs 32f made any difference as gegl processes at double? precision
32f.

> > *Does the total number of layers, masks, and/or alpha channels matter?
> > Or is it just the overall image size in pixels?
> It's (roughly) overall image size times number of image-sized layers.

OK, good to know. Gimp seems to throw in alpha channels all over the
place, not sure why. I never add alpha channels deliberately, but I've
been deleting a lot of them.

> For more detail, say which operations exactly are unbearably slow....

I do a lot of painting with large and small brushes on layer masks.
That brush just crawls across the screen, makes real-time painting
impossible. I think I will try working on scaled-down files until the
masks are right, then scale up to the original size and drag the masks
over to the full-sized image file.

Regarding how to make optimal use of the available hard drives, there
was a time when working on one drive, with swap files on another
drive, etc really did make a big difference for image editing
applications. I'm not sure about today's hard drives (and none of my
drives are "today's"). Any thoughts on optimal layout of swap,
GimpSwap, Gimp's temporary folder, and the actual working image files?
And do you have any idea what large file(s) might Gimp have been
writing to its system configuration file that filled up 15GB? The undo
history?

Thanks very much! for all the concrete information. I will be putting
it to good use. One nice thing about having two processors instead of
just the one is I'll be able to add twice as much ram, which seems to
be the main thing needed for faster image editing.

Elle