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5. 运行MPICH程序
多机环境中运行MPICH程序与单机环境类似，可以用mpirun来进行。运行程序前先创建一个machinefile文件，其中列出要使用的结点机名，然后用命令“mpirun -machinefile 文件名 ...”来在指定的结点上运行程序。例如，假设用户登录在结点node2上，文件mfile中包含下述内容：
node3
node4
则命令：
mpirun -machinefile mfile -np 3 cpi
将用node2，node3 和node4来运行程序cpi，每个结点一个进程，这是因为默认情况下mpirun总是将当前结点添加到程序的结点机列表中。如果不希望使用当前结点(node2)，可以加上-nolocal选项：
mpirun -nolocal -machinefile mfile -np 3 cpi
选项-np给出的进程数与-machinefile给出的文件中的结点机数不一定要相等。如果进程数少于结点机数，则程序只使用其中的一部分结点。如果进程数多于结点机数，则一些结点上会运行多于一个进程。

SYNOPSIS
Single Process Multiple Data (SPMD) Model:

mpirun [ options ] <program> [ <args> ]

Multiple Instruction Multiple Data (MIMD) Model:

mpirun [ global_options ]
[ local_options1 ] <program1> [ <args1> ] :
[ local_options2 ] <program2> [ <args2> ] :
... :
[ local_optionsN ] <programN> [ <argsN> ]

Note that in both models, invoking mpirun via an absolute path name is equivalent to specifying the --prefix option with a <dir> value equivalent to the directory where mpirun resides, minus its last subdirectory. For example:

% /usr/local/bin/mpirun ...

is equivalent to

% mpirun --prefix /usr/local

QUICK SUMMARY
If you are simply looking for how to run an MPI application, you probably want to use a command line of the following form:

% mpirun [ -np X ] [ --hostfile <filename> ] <program>

This will run X copies of <program> in your current run-time environment (if running under a supported resource manager, Open MPI's mpirun will usually automatically use the corresponding resource manager process starter, as opposed to, for example, rsh or ssh, which require the use of a hostfile, or will default to running all X copies on the localhost), scheduling (by default) in a round-robin fashion by CPU slot. See the rest of this page for more details.

nohup /home/software/openmpi-1.2.2-intel9/bin/mpirun -np 8 /home/bin/vasp.openmpi >out &