Public bug reported:
This bug also occurs with openmpi
<https://bugs.launchpad.net/ubuntu/+source/openmpi/+bug/515496>
Using a Karmic 8 cores amd64 system with shared memory, any MPI
computation with mpich puts extreme load on the system, which affects
the 'user experience' : the whole system gets stuck and very slow to
respond. Such behaviors where not found with previous Ubuntu releases
(8.04. 8.10, 9.04) where the usage of the system was not noticeably
affected, while 100 % of the machine was indeed running on computations.
This may be related to changes in the kernel itself, as mpich was already used
on Jaunty, without problems.
When the OnDemand kernel load manager service is active, the cores are not
equivalent, and some remain at 20% load, which desynchronize the MPI
computation. The 'user experience' is still slightly better.
Unactivating the OnDemand kernel load manager service, all cores work equally,
and computation is performed, but systems is nearly halted (very few resources
remain for the system and the window manager).
** Affects: mpich (Ubuntu)
Importance: Undecided
Status: New
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mpich slows down whole system on Karmic
https://bugs.launchpad.net/bugs/515521
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