Re: gEDA-user: PCB GTK version...

[Bill Wilson <billw@xxxxxxxxxxxxxx>]

On Wed, 27 Jul 2005 15:41:58 +0200
Jakub Piotr C__apa <jpc@xxxxxxxxxxxxx> wrote:

> Ales Hvezda wrote:
> > [snip]
> > 
> > Interesting thread, but nobody answered my first question:
> > 
> > What specifically is it about gtk+ 2.[4|6] that is so much slower than
> > say gtk+ 1.x? 
> 
> That's a good question (bot wrong list probably)... :)

I think he's asking for slower specifics wrt gschem and the gtk pcb
and not in general.

> > I haven't notice critical amounts of slowdown in gschem
> > or gtkPCB on my P2-400/256M.  Certainly pango and friends do impact text
> > rendering performance and I have noticed longer startup times because
> > of the larger number of dependencies
> 
> Blender also has many dependencies and starts almost instantly.

On Ales' P2-400?  Blender takes several seconds to start on my k6-2 450.

I've a test program that shows Gtk pango text draws using gdk_draw_layout() can
be 20-40 times slower than xlib text draws using gdk_draw_string(), but pango
text is used in Gtk PCB only for pinout numbers and I'm not sure if it is
used on gschem schematics.  The pcb and gschem drawing areas use
gdk draw functions which are mostly short simple single function wrappers around
the xlib equivalent calls so raw drawing speed should be good.

On my k6-2 450 I see a slight slowdown of Gtk PCB compared to Xaw but
the Gtk PCB is still quite usable.  The menus appear almost instantly and
scrolling of a large layout is only slightly slower than Xaw PCB.  The Xaw
scrolling is also noticeably slower than on my Athlon 2000 machine, go figure!
At startup the Gtk PCB window appears in about 1.5 seconds and
it takes another second for the drawn layout to appear.  The Xaw PCB window
takes about 1.25 seconds to appear and the layout is drawn in slightly less than
another second.  I could spend more time and get some accurate timings, but
the slowdown is not, as Ales put it, "critical".

Just to support Ales' request, we need specific examples of where gschem or
Gtk PCB (compared to the Xaw version) gets to be objectionably slow and
on what hardware.  Based on the two examples (p2-400 and k6-2 450) so far
in this thread I would think we are talking at least sub 400 MHz machines and
I'm noticing the Xaw PCB version to start slowing down at this level also.

While Gtk can be slow for apps that heavily use Pango or large treeviews,
it really depends on the app and general Gtk complaints don't really help
with respect to any possible real issues with Gtk PCB or gschem.

And we still don't know the original posters hardware or what his
specific complaint was, and yet it sure lit some fires :)

Bill