crash in profiling mode

Simon Marlow
Wed, 30 Oct 2002 11:08:38 -0000

> Another question: The profiling mode of GHC-4.08.2 did also output (in
> mode +RTS -p) the time spent on garbage collection (as an additional
> percentage of overall running time).
> With the programs I tested so far under GHC-5.04.1, I never=20
> saw such an
> indication in, although for the same programs under
> GHC-4.08.2 considerable garbage collection times were measured.
> Does this mean that:
>  a) the indication of garbage collection times has been dropped from
>     profiling reports (can I obtain them in another way?),
> or
>  b) the newer GHC is so smart that it optimised away the need for
>     garbage collection in the particular (few) programs I tested, but
>     otherwise the GC times will show up in profiling reports,
> or
>  c) something else?

The inclusion of GC time in the report was wrong, since GC time wasn't
included in the figure for total time, so you could get GC times of >
100%.  You can get a measure of GC time vs. mutator time by adding '+RTS
-sstderr' to the command line.