[ft] ftbench result interpretation

[Olivier DOLE]

Hi all,

I am currently working on freetype2 as possible font renderer for OSB
browser and my first work is performance considerations... and of
course understand how it works. So i have ran ftbench tests and I have
problems in interpreting results concerning PCF fonts.
Here are my results:
./ftbench -C /usr/lib/X11/fonts/100dpi/timR10.pcf.gz
Load                     
: 2.221 us/op
Load (image cached)       :   inf us/op
Load (sbit cached)        : 0.257 us/op
Render                   
:   nan us/op
Get_Glyph                
:   nan us/op
Get_CBox                 
:   nan us/op
Get_Char_Index            : 0.170 us/op
Get_Char_Index (cached)   : 0.114 us/op
Iterate CMap              : 157.996 us/op
New_Face                  : 3308.312 us/op

 ./ftbench /usr/lib/X11/fonts/100dpi/timR10.pcf.gz
Load                     
: 2.221 us/op
Render                   
: 2.748 us/op
Get_Glyph                 : 3.367 us/op
Get_CBox                  : 2.751 us/op
Get_Char_Index            : 0.144 us/op
Iterate CMap              : 153.512 us/op
New_Face                  : 3194.628 us/op

So what i don't understand is when I use the cache comparison option
some tests like "Render" test display "nan". So first, what does this
"nan" means ? and second question, why in one case it displays "nan" as
a result and in the other case it displays a valid (?) result ?
Best regards,

Olivier