In general, jobs are submitted to CCR resources using a batch computing system. This provides the best means to insure an equitable distribution of CCR's computing resources among all users. Each submitted job is assigned a queue priority, which essentially determines when the job will run. There are several factors which determine the priority that is assigned to a user's job. These factors are described below.

The four factors which determine a job's priority are:

Direct Financial Support to CCR, which consists of:

• Decanal Support (provided by CAS, SEAS, etc)
• PI Submissions
• PI Fundable (those PIs in Science, Engineering, and other areas where there are standard mechanisms for funding, including NSF and NIH)
• Actual Dollars Provided (3-Year Average)

Fairshare

• Fairshare is a mechanism which allows historical resource utilization information to be incorporated into job feasibility and priority decisions. In simple terms, the more you use the resource, the less priority your jobs receive.
• CCR policy is based on GROUP usage, not individual usage. Each job's priority will be affected by the activity of the users within the group.

Queue Time

• The longer your job is in the queue, the more priority your job will get.

Size of Job

• Larger jobs get more priority then smaller jobs.

Priority Calculations

A slightly simplified view of scheduling priority (ignores some fairshare decay factors that have only a slight impact):

Priority =

where (parentheses indicate the maui subcommand that can be used to check the current values):

	Number of nodes requested
	Weighting factor for nodes requested (diagnose -p)
	Time spent waiting in queue [in minutes]
	Fairshare weighting factor (diagnose -p)
Usage	Fairshare Usage (diagnose -f)
Target	Fairshare Target percentage (diagnose -f)
	Weighting factor for financial contribution (diagnose -p)
	Financial contribution [see table]

An example

User A belongs to group B (Xfinancial=4.0, Wfinancial=800), and submits a 64 node job. A has only been a moderate user for the last month (Usage=5%, Target=25%, Wfairshare=500). After 1 day of waiting in the queue, the job's priority is approximately:

Priority = 64*16+(24*60)+500*(25-5)+800*4.0 = 15664

The priority values for jobs in the queue can be checked using the maui diagnose -f command.