To my
> > Dear GHC team,
> >
> > It looks like ghc-6.12.1 reports erroneous time profiling --
> > when the Main module of the project is made under -O.
> > [..]
> > This is for ghc-6.12.1 made from source for Debian Linux and
> > i386-like.
> >
> > Main.main calls for Complete.complete, `complete' calls for
> > eLoop inside its source.
> > eLoop must take almost all the time.
> > My whole user library is made under -O -prof, and
> > --enable-library-profiling.
> > Main is compiled by
> > ghc $dmCpOpt -prof --make Main
> > and run by ./Main +RTS -M400m -pT -RTS
> > For this key, the profiling report Main.prof looks natural and shows
> > eLoop -- 97%.
> >
> > But for ghc $dmCpOpt -O -prof --make Make,
> >
> > it shows a different thing: zero for eLoop and 99% for `main'.
>
On Wed, Feb 03, 2010 at 05:38:36PM +0100, Daniel Fischer wrote:
> Could be that eLoop is inlined with -O.
Thank you.
I also thought about this. But the question still looks difficult.
> Try
>
> ghc $dmCpOpt -O -prof -auto-all --make
>
> That should show eLoop (if that's a top-level declaration, otherwise you'd
> have to insert a pragma {-# SCC "eLoop" #-} manually).
>
eLoop is not a top-level declaration, and I do set {-# SCC "eLoop" #-}.
The key combination
ghc $dmCpOpt -prof --make Main
shows 95% for eLoop,
and adding -O to this line shows 0% for eLoop, independently on
presence of -auto-all in this line
(the whole library is made under -O -prof).
Yes, I recall that the effect may be of inlining.
But, generally, how to detect sensibly the time consuming functions?
This inlining presents a puzzle here.
Is it possible to
compile Main.hs and Complete.hs under -O0 -inline-not,
compile all the other modules under -O
?
(how?).
If it is possible, will this make easier to understand the profiling
report?
Regards,
-----------------
Serge Mechveliani
mech...@botik.ru
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