Hardware and performance

I have enabled the MDL_PERF parameters to log to the 'log'. But where can I find this 'log'? I'm testing my brand new dual opteron 242 - 2gig ram - 72 GB raptor setup (yummie).

//   Capture performance profiling data
   define('MDL_PERF'  , true);
//
//   Capture additional data from DB
   define('MDL_PERFDB'  , true);
//
//   Print to log (for passive profiling of production servers)
   define('MDL_PERFTOLOG'  , true);
//
//   Print to footer (works with the default theme)
//   define('MDL_PERFTOFOOT', true);