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

[Liam R E Quin <liam holoweb net>]

On Thu, 2013-02-28 at 12:16 -0500, Elle Stone wrote:

> Short of building a new computer (not going to happen!), what else can
> I do to improve Gimp performance? Which hardware upgrade(s) might give
> the most performance improvement for the least amount of money?

More memory. Max it out.

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...

(2) in gimp...

make the gimp tile cache be large - this is the amount of the image gimp
will keep in memory, and for a 4G 64-bit system you want it to be 3G,
for a 16G system I'd set it to 12 or 4G probably.

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.


> *We can replace the single processor with two slightly faster
> processors. Will two processors make a difference?
Somewhat, because one can be running gimp while the other is working on
updating the screen, running the Web browser etc.

> *Will reconfiguring the sata drives to use their fastest write speed
> help? How much does write speed matter?
Not significantly - read speed matters more on Unix/Linux systems,
because writing todisk is done in the background aynchronously.

> *Are there figures for optimal RAM, other than "as much as possible"?
I have 8G for use with GIMP 2.7 or 2.8. I am about to order a system
with 32G for using higher bit depths.

> *How much does the GPU affect Gimp's processing speed? Would upgrading
> the graphics card help? If so, how much of an upgrade would it take to
> make a perceptible difference?

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)

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.
$ fc-list | wc -l
2533

so I have 2,500 fonts installed right now (and many more that are not
installed).


> 3. Image size, type, precision
>
> Short of working on smaller files, what else affects how much
> processing power Gimp needs? Specifically,
>
> *Does it make a difference what precision is used? 32-bit floating
> point vs 16-bit integer?
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)

> *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.

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

Liam

-- 
Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
Pictures from old books: http://fromoldbooks.org/
Ankh: irc.sorcery.net irc.gnome.org freenode/#xml