This example shows a technique for allocating resources from multiple resource pools. It shows how to choose a pool from which to draw a resource, based on given criteria.
There are two main components of the model.
Request Generation and Queuing
Resource Pools and Resource Allocation
The Entity Generator block generates requests using a Uniform distribution. In order for these requests to be acted upon, they require a resource from one of the two resource pools. Each of the requests has an attribute that specifies the kind of resource it requires. The requests move to one of the queues dedicated for each type of resource pool.
The model has two resource pools, Type 1 and Type 2. The Type 1 and Type 2 Resource Pool blocks model the pools. These pools hold the resources before and after their use. The size of each pool is defined as parameter of the corresponding block.
The Resource Acquirer and Resource Releaser blocks manage the acquisition and the return of the resource. The Entity Server block in that region models the duration for which the resources are used.
This model includes the following plots.
The Pending Type 1 Requests and Pending Type 2 Requests plots show the number of requests waiting for resources from the corresponding pools. You can see that more requests for Type 1 resources wait compared to requests for Type 2 resources.
The Type 1 Resources in Use and the Type 2 Resources in Use plots show the instantaneous values of the number of resources available for use in the corresponding resource pools.
The average wait time for acquiring each type of resources is reported by the Resource Acquire blocks for Type 1 Resource and Type 2 Resource.
Average Wait Time for Resource Type 1 = 0.00 Average Wait Time for Resource Type 2 = 0.00
The average amount of resources in use at each resource pool is reported by Resource Pool blocks for Type 1 Resource and Type 2 Resource.
Average Use of Resource Type 1 = 0.47 Average Use of Resource Type 2 = 0.50
The model has the following configuration:
Resource request distribution: Type 1 = 0.4, Type 2 = 0.6
Duration of Type 1 resource use : 0.05
Duration of Type 2 resource use : 0.07
Type 1 pool size : 4
Type 2 pool size : 8
From the above results, you can see that the larger pool size of Type 2 resources results in a lower average wait time even with a higher request rate and longer duration of resource use.
To vary system behaviors, like the number of resources available and wait times for resources, change the following settings:
The probabilities for changing the generation rate of the resource requests in the
Intergeneration time action parameter of Entity Generator.
Service time parameter of the Entity Server blocks in the Resource Pool and Resource Allocation regions of the model for changing the duration of the resource usage.
Resource amount parameter of the Type 1 Resource Pool and Type 2 Resource Pool blocks to change the number of resources in the pool.