pango / fontconfig / cairo performance with rrdtool


A few months back I ported rrdtool ( over from
libart/freetype to cairo/pango. It all went quite well and the
resulting graphs look cool. But when it comes to performance things
look realy bad.

Creating a little test graph with rrdtool 1.2 (libart/freetype)
takes about 0.01s while the same graph with (cairo/pango) takes
0.2s in other words, I am seeing a 20 times slow down. Creating
several graphs in the same session does not change things much.

I have sat down with callgrind to analyze and found that 80% of the
time is spend in the


function. I bet I am doing something terribly wrong here, since I
use the same font in only 2 sizes all over the graph.

I have based my code on the example in the documentation
but maybe this is not optimal. I tried to add some caching but it
did not help much.

I have put a few details up on

any ideas ?


Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland tobi oetiker ch ++41 62 775 9902 / sb: -9900

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