Abstract: The processing resource may be competed by multiple jobs in a parallel computer system,in which the operating system kernel determines how many and which processors are to be allocated to a job by using a processor allocation policy.Investigation is made of the issues involved in constructing a processor allocation policy for large scale,message passing parallel computers to support a scientific workload.It is argued that partition policies must satisfy nearly equal resource allocation to all runnable jobs and allocate the adjacent processors to a job.Finally,rectangle and un rectangle policies are proposed and the performance of the two policies is compared.