Retainer profiling -- too slow?
marlowsd at gmail.com
Wed Jul 30 05:01:40 EDT 2008
Tim Chevalier wrote:
> Hi all,
> Are there any known problems with retainer profiling in GHC 6.8.2? I
> have a program that takes 3 minutes to run with "normal" profiling
> enabled (+RTS -P -RTS), but with +RTS -P -hr -RTS, it's 20 minutes and
> counting. I can tell that progress is being made since the .hp file
> keeps getting bigger, but that seems like a lot of overhead.
> I can try to come up with a smaller test case if necessary; just
> wanted to see if there's any known problem.
It certainly is slow, especially with large heaps, because IIRC it has to
do multiple traversals of the heap. The +RTS -sstderr output will tell you
how much time is spent doing retainer profiling. (also retainer profiling
is often not terribly useful IMO).
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