Interpretation of memallocs returned by @timed


I was trying to find some information about the memory allocation counters that the @timed macro returns. These should probably be explained in the documentation of @timed. I did find some comments in the source code for the returned data structure:

struct GC_Diff
    allocd      ::Int64 # Bytes allocated
    malloc      ::Int64 # Number of GC aware malloc()
    realloc     ::Int64 # Number of GC aware realloc()
    poolalloc   ::Int64 # Number of pool allocation
    bigalloc    ::Int64 # Number of big (non-pool) allocation
    freecall    ::Int64 # Number of GC aware free()
    total_time  ::Int64 # Time spent in garbage collection
    pause       ::Int64 # Number of GC pauses
    full_sweep  ::Int64 # Number of GC full collection

Would anyone be able to explain in a bit more detail how these should be interpreted? Which of these are particularly interesting from a performance perspective? Coming from Fortran, I’d basically want to know how many times the equivalent Fortran code would call allocate (i.e., array allocations, as opposed to allocations for scalar variables). Is this bigalloc? What are pool allocations, conceptually?