Approximate VCCs: A new characterization of multimedia workloads for system-level MpSoC design

System-level design methods specifically targeted towards multimedia applications have recently received a lot of attention. Multimedia workloads are known to have a high degree of variability. Therefore, designs based on a worst-case analysis of such workloads tend of be overly pessimistic. We address this issue by introducing a new concept called approximate variability characterization curves (or Approximate VCCs), to characterize the "average-case" behavior of multimedia workloads in a parameterized fashion. Since most multimedia applications only have soft real-time constraints, it is often possible to tolerate a small amount of performance degradation. By allowing such small degradations in the performance, large amounts of resource savings are possible. The concept of Approximate VCCs that we present in this paper allows a designer to quantitatively account for the performance degradation and the associated resource savings. We illustrate this using two typical system design cases.