Using and Administering

blocking

Blocking specifies that tasks be assigned to machines in multiples of a certain integer. Unlimited blocking specifies that tasks be assigned to the each machine until it runs out of initiators, at which time tasks will be assigned to the machine which is next in the order of priority. If the total number of tasks are not evenly divisible by the blocking factor, the remainder of tasks are allocated to a single node.

The syntax is:

blocking = integer|unlimited

Where:

integer

specifies the blocking factor to be used. The blocking factor must be a positive integer. With a blocking factor of 4, LoadLeveler will allocate 4 tasks at a time to each machine with at least 4 initiators available. This keyword must be specified with the total_tasks keyword. For example:

blocking = 4
total_tasks = 17
 

LoadLeveler will allocate tasks to machines in an order based on the values of their MACHPRIO expressions (beginning with the highest MACHPRIO value). In cases where total_tasks is not a multiple of the blocking factor, LoadLeveler assigns the remaining number of tasks as soon as possible (even if that means assigning the remainder to a machine at the same time as it assigns another block).

unlimited

Specifies that LoadLeveler allocate as many tasks as possible to each machine, until all of the tasks have been allocated. LoadLeveler will prioritize machines based on the number of initiators each machine currently has available. Unlimited blocking is the only means of allocating tasks to nodes that does not prioritize machines primarily by MACHPRIO expression.