On Tue, 3 Sep 2002, Xuehua Chen wrote:
> I want to tune LAM MPI to find the best configuration for some machine
> that will achieve
> best performance.
>
> It seems to me that for the usysv mode, the parameters that we can
> change are:
> --with-shm-poolsize
> --with-shm-maxalloc
> --with-shm-short
>
> Are there any other parameters that we can tune?
>
> What parameters to tune that will affect the performance of sysv mode?
The same parameters also control the sysv RPI. Some of the behaviors can
also be set using environment variables:
LAM_MPI_POLLYIELD
sysv and usysv
If non-zero, LAM will attempt to yield CPU when polling
LAM_MPI_SHMPOOLSIZE
sysv and usysv
Size of the shared memory pool (same thing as --with-shm-poolsize)
LAM_MPI_SHMMAXALLOC
sysv and usysv
Max allocation area (same thing as --with-shm-maxalloc)
LAM_MPI_READLOCKPOLL / LAM_MPI_WRITELOCKPOLL
usysv
Integer - how many times to spin before yielding on lock
The environment variables over-ride the configure defaults, so you can
play to find the best values for your application without having to
rebuild LAM :)
Hope this helps,
Brian
--
Brian Barrett
LAM/MPI developer and all around nice guy
Have a LAM/MPI day: http://www.lam-mpi.org/
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