How to use and interpret DEBUG?

[Rahkonen Jukka]

Hi,
 
I got interested in comparing the performance of using tiled geotiffs with overviews v.s. JPEG 2000 images.  So far I have set "DEBUG ON" in map object, named a logfile in the web object, made two layers from geotiffs and JPEG 2000s and set "DEBUG ON" for the both.
Now when I send requests to Mapserver I get new lines to logfile, but I do not know where I should find the time that it takes to render the layer. Here is an splitted example of the lines I am getting to the log:
 
Mon Apr 03 13:08:52 2006,      #this is obviously date and time
2732,        # no idea about what this is
1xx.xx.xx.xxx,      # IP address of the requesting computer, I believe
Tifspeedtest,       # name defined in the mapfile
3,       # no idea about this, but value seems to be always "3"
2539375.000000 7220000.000000 2545625.000000 7225000.000000,      # extents of the request
     -1.000000 -1.000000, # no idea about these two either
Geotiff ,  # names of the requested layers
normal execution # the result
 
 
Now I wonder if this is the way to do this, and if so, then what I should think about the numbers. I wonder also why I get two lines per request if I send "&mode=map&layers=Geotiff" request through browser, but nothing at all if I am sending WMS "GetMap"requests with the browser for the same layer, even if I do get the map.
 
Might there be some good document about using debug available? Those I have found helped me this far but not any further. 
 
Regards,
 
-Jukka-