[mvapich-discuss] Rank Placement in MVAPICH

[Hari Subramoni]

Hi Vaibhav,

To get a block allocation just repeat n1 8 times then n2 8 times in your
hostfile. This will change the allocation to block.

1: n1
2: n1
..
8: n1
1: n2
2: n2
..
8: n2

Please refer to the MVAPICH2 userguide at the following link for more
information

http://mvapich.cse.ohio-state.edu/support/user_guide_mvapich2-1.6.html#x1-240005.2.1

Thx,
Hari.


On Thu, 7 Apr 2011, vaibhav dutt wrote:

> Hi,
>
> I am trying to execute a job  of 16 processes across two nodes and my
> hostfile looks like
>
> n1:8
> n2:8.
>
> I notice that the ranks   0,2,4,6,8,10,12,14 are on node 1 and
> 1,3,5,7,9,11,13,15 are on node 2 which seems to be
> cyclic distribution. Is this the default rank placement strategy in MVAPICH
> as I did not give any special option on runtime
> for the rank distribution to be cyclic. How to change it to block?
>
> Thanks
>