16.2.1. Cluster migration

Only one cluster, either big or LITTLE, is active at any one time, except very briefly during a cluster context switch to the other cluster. To achieve the best power and performance efficiency, the software stack runs mostly on the energy-efficient LITTLE cluster and only runs for short time periods on the big cluster. This model requires the same number of cores in both clusters.

This model does not cope well with unbalanced software workloads, that is, workloads that place significantly different loads on cores within a cluster. In such situations, cluster migration results in a complete switch to the big cluster even though not all the cores need that level of performance. For this reason cluster migration is less popular than other methods.

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