[Haskell-cafe] Strange parallel behaviour with Ubuntu Karmic
/ GHC 6.10.4
Neil Brown
nccb2 at kent.ac.uk
Mon Nov 16 04:38:29 EST 2009
Michael Lesniak wrote:
> Hello,
>
> I've written a smaller example which reproduces the unusual behaviour.
> Should I open a GHC-Ticket, too?
>
Hi,
I get these results:
$ time ./Temp +RTS -N1 -RTS 16
real 0m16.010s
user 0m10.869s
sys 0m5.144s
$ time ./Temp +RTS -N2 -RTS 16
real 0m12.794s
user 0m13.341s
sys 0m7.136s
Looking at top, the second version used ~160% CPU time (i.e. it was
using both cores fairly well). So I don't think I get the same bad
behaviour as you. Those sys times look high by the way -- I guess it's
all the calls to getTime? I wonder if that number might be causing the
problem; can you replicate it with lower sys times?
Thanks,
Neil.
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