[Haskell-cafe] Using PAPI to measure performance with CPU events

Dear all, I have added a page to the GHC commentary explaining how to use the PAPI library together with GHC to gather performance information from your CPU (cache misses, branch misprediction). At present only cache miss information is supported in a platform independent way (though not tested). Also, this implementation separates the performance information for the garbage collector and the mutator so it is quite useful if you are implementing an optimisation. The page also has some patches to use PAPI on the nofib suite. These patches are eventually going to make it into the HEAD, but I thought someone might find them useful meanwhile. Cheers, Alexey