Re: slow drawing with large images

[Ethan A M. <merritt@u.washington.edu>]

On Wednesday 22 February 2006 06:37 am, Bastian Maerkisch wrote:
> When drawing large images (binary and ascii) gnuplot is veeeery
> slow on my (windows) machine. E.g. with an image (RGB) of 1024*256
> pixels it takes about >5.5s to output on any terminal.
> 
> Profiling reveals that gnuplot spends >75% of it's time in
> gp_realloc()  <--  cp_extend() <--  get_data().

OK, I've done a proper profiling run under linux (Mandriva 2006).

lascaux [141] cat rgbimage.dem
plot '< convert sen.jpeg avs:-' binary filetype=avs with rgbimage
replot
replot
replot
replot
replot

lascaux [142] identify sen.jpeg
sen.jpeg JPEG 1280x899 DirectClass 256kb 0.090u 0:01

Profiling output:
    %   cumulative   self              self     total
  6.81      6.39     6.39                             cb2gray (pm3d.c:174 @ 80c666c)
  5.53     11.57     5.19                             store2d_point (plot2d.c:842 @ 80b8711)
  4.66     15.94     4.37                             X11_image (x11.trm:1868 @ 80efae3)
  3.74     19.45     3.51                             cb2gray (pm3d.c:180 @ 80c66ee)
  3.50     22.73     3.28                             cb2gray (pm3d.c:178 @ 80c66d0)
  3.09     25.63     2.90                             store2d_point (plot2d.c:841 @ 80b849d)
  2.87     28.32     2.69                             store2d_point (plot2d.c:843 @ 80b899e)
[snip 200 lines]
  0.00     93.81     0.00     6954     0.00     0.00  gp_realloc (alloc.c:295 @ 804bc00)
  0.00     93.81     0.00     6930     0.00     0.00  cp_extend (plot2d.c:144 @ 80b587c)

> 
> Can anybody confirm this behaviour on non-windows machines?

No.  
Under linux the gp_realloc() takes 0 time for all intents and purposes.

Most time spent (19% net) is in routine store2d_point()  
Next largest chunk of time (14%) is in cb2gray()
After that no single routine stands out

> Or is this a problem of gp_realloc() on Windows?

No idea where the problem is under Windows.



Separate timing run (no profiling):

lascaux [2389] time ./gnuplot rgbimage.dem
1.854u 0.249s 0:02.70 77.4%     0+0k 0+0io 54pf+0w

So, 6 times through plotting a 1280x899 rgbimage takes less than
2 seconds including the file reading and program startup.
Your reported 5+ seconds for 1 plot of an image 1/3 that size
seems excessive any way you look at it.

-- 
Ethan A Merritt
Biomolecular Structure Center
University of Washington, Seattle 98195-7742