Profile: zero total time

Matthew Farkas-Dyck strake888 at
Thu Jul 7 20:44:57 CEST 2011

I am trying to take a profile of a program, but when I run it, the
total time (as given in the profiling report file) is zero!

total time  =        0.00 secs   (0 ticks @ 20 ms)

However, the -s option yields the following data:

   3,429,300,984 bytes allocated in the heap
     210,760,024 bytes copied during GC
      23,647,224 bytes maximum residency (13 sample(s))
       3,536,968 bytes maximum slop
              58 MB total memory in use (0 MB lost due to fragmentation)

  Generation 0:  6339 collections,     0 parallel,  1.14s,  1.42s elapsed
  Generation 1:    13 collections,     0 parallel,  0.28s,  0.34s elapsed

  INIT  time    0.00s  (  0.00s elapsed)
  MUT   time   96.60s  (124.50s elapsed)
  GC    time    1.42s  (  1.75s elapsed)
  RP    time    0.00s  (  0.00s elapsed)
  PROF  time    0.00s  (  0.00s elapsed)
  EXIT  time    0.00s  (  0.00s elapsed)
  Total time   98.02s  (126.25s elapsed)

  %GC time       1.4%  (1.4% elapsed)

  Alloc rate    35,498,347 bytes per MUT second

  Productivity  98.5% of total user, 76.5% of total elapsed

The time taken by each cost centre is also zero. The program is
compiled with options "-prof -auto-all -caf-all" by GHC 7.0.3 and run
with RTS options "-p -s".

The true time taken is certainly NOT zero. How is this possible?


Matthew Farkas-Dyck

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