Profiling bugs in 6.8.1 and 6.6.1

Daniel Fischer at
Sun Nov 25 17:27:01 EST 2007

first let me remark that 6.8.1 is really remarkable, compiles faster and 
produces faster executables than 6.6.1.

However, I have a problem with profiling, the time is always reported as 0.00 

	Sun Nov 25 22:58 2007 Time and Allocation Profiling Report  (Final)

	   p28Master +RTS -P -hb -sstderr -RTS MMDataA

	total time  =        0.00 secs   (0 ticks @ 20 ms)
	total alloc = 1,313,421,840 bytes  (excludes profiling overheads)

although it took more than 15 seconds:

  INIT  time    0.00s  (  0.00s elapsed)
  MUT   time   16.10s  ( 16.41s elapsed)
  GC    time   10.76s  ( 11.16s elapsed)
  RP    time    0.00s  (  0.00s elapsed)
  PROF  time    0.00s  (  0.00s elapsed)
  EXIT  time    0.00s  (  0.00s elapsed)
  Total time   26.86s  ( 27.57s elapsed)

Could that be caused by commenting out the lines
ifeq "$(GhcThreaded)" "YES"
SRC_HC_OPTS += -threaded

in compiler/Makefile.ghcbin ?
I did that because if I build ghc with -threaded, the times reported with 
:set +s
in ghci are rubbish (I have a linux 2.4.20 kernel, and the threads don't 
support process-wide times; and no, I'm not likely to upgrade, SuSE 8.2 is 
the only OS that ever worked properly for me).
If that's the cause, too bad, I'll have to revert to 6.4.2 for profiling :(

In 6.6.1, -O2 and -prof -auto-all don't work together well, I have a programme 
where that combination of options results in an instant wrong output, while
the combinations
-prof -auto-all
-O1 -prof -auto-all
-O2 -prof
lead to the correct output calculated in 10 to 13 seconds.
If you're interested in that bug, I could send you the code, it's short 


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