  Extensive prior research has focused on alleviating the characteristic poor
cache locality of graph analytics workloads. However, graph pre-processing
tasks remain relatively unexplored. In many important scenarios, graph
pre-processing tasks can be as expensive as the downstream graph analytics
kernel. We observe that Propagation Blocking (PB), a software optimization
designed for SpMV kernels, generalizes to many graph analytics kernels as well
as common pre-processing tasks. In this work, we identify the lingering
inefficiencies of a PB execution on conventional multicores and propose
architecture support to eliminate PB's bottlenecks, further improving the
performance gains from PB. Our proposed architecture -- COBRA -- optimizes the
PB execution of both graph processing and pre-processing alike to provide
end-to-end speedups of up to 4.6x (3.5x on average).
