[yt-users] HaloFinder- parallel is slower?

Agarwal, Shankar sagarwal at ku.edu
Mon Dec 7 20:54:08 PST 2009


Hi,

I ran yt's HaloFinder routine on 1 processor, and then on 8 processors. Both give identical output : 40,000 halos starting from 512^3 particles.

1 processor   :   took 1 hour 45 minutes.
8 processors :   took 2 hours.


My script is  hop_yt.py....

from yt.mods import *
fn = "RedshiftOutput0002"
pf = load(fn)
halos = HaloFinder(pf,40,padding=0.02)
halos.write_out("HopAnalysis.out")


commands I used....

mpirun -np 1 python hop_yt.py --parallel
mpirun -np 8 python hop_yt.py --parallel


Any idea why 8 cpus would take longer ?


shankar



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