A global front end scheduler to schedule instruction sequences to a plurality of virtual cores implemented via a plurality of partitionable engines. The global front end scheduler includes a thread allocation array to store a set of allocation thread pointers to point to a set of buckets in a bucket buffer in which execution blocks for respective threads are placed, a bucket buffer to provide a matrix of buckets, the bucket buffer including storage for the execution blocks, and a bucket retirement array to store a set of retirement thread pointers that track a next execution block to retire for a thread.