profile not showing it all?

Hi, since my application takes up way to much memory, i decided to profile it (compile d it with -prof and -auto-all). After running it with +RTS -hc, it shows a graph that reaches a peak at around 85mb. However, when i check the memory usage with 'top' i see the application reach over 300mb. What am i missing here? PS the application is a large attribute grammar that performs program analysis on an AST that represents an application. regards, Niels.