Disclosed are various embodiments that utilize conflict cost for workload placements in datacenter environments. In some examples, a protected memory level is identified for a computing environment. The computing environment includes a number of processor resources. Incompatible processor workloads are prohibited from concurrently executing on parallel processor resources. Parallel processor resources share memory at the protected memory level. A number of conflict costs are determined for a processor workload. Each conflict cost is determined based on a measure of compatibility between the processor workload and a parallel processor resource that shares a particular memory with the respective processor resource. The processor workload is assigned to execute on a processor resource associated with a minimum conflict cost.