Toward high performance asynchronous RTM with temporal blocking and buffered I/O

During the forward and backward modeling in Reverse Time Migration (RTM), stencil computations constitute one of the main computationally intensive components. Their classic implementation based on Spatial Blocking (SB) is subject to performance limitation on modern multicore architectures due to several reasons, including nonuniform memory access, memory bandwidth starvation, load imbalance, and limited data locality. The Multicore Wavefront Diamond-tiling Temporal Blocking technique (MWD-TB) introduced in (Malas, PhD thesis 2015, Malas et al., SIAM SciCo 2015, Malas et al., ACM Trans 2017) aims at reducing the memory bandwidth requirement of stencil computations by increasing cache reuse within successive time steps. The authors in (Akbudak et al. IJHPCA 2020) integrate the MWD-TB technique into the modeling phase and the authors in (Qu et al., KAUST Tech Report 2020) eventually embed it into the full RTM using in-memory I/O operations snapshotting for the imaging condition and illustrate with the Salt3D dataset. In this paper, we further enable Out-Of-Core (OOC) I/O snapshotting operations on the Lustre parallel file system using the buffering strategy from MLBS (Alturkestani et al., EuroPar 2020). We present preliminary results using the Marmoussi 3D dataset.