  This article features extended summaries and retrospectives of some of the
recent research done by our research group, SAFARI, on (1) various critical
problems in memory systems and (2) how memory system bottlenecks affect
graphics processing unit (GPU) systems. As more applications share a single
system, operations from each application can contend with each other at various
shared components. Such contention can slow down each application or thread of
execution. The compound effect of contention, high memory latency and access
overheads, as well as inefficient management of resources, greatly degrades
performance, quality-of-service, and energy efficiency. The ten works featured
in this issue study several aspects of (1) inter-application interference in
multicore systems, heterogeneous systems, and GPUs; (2) the growing overheads
and expenses associated with growing memory densities and latencies; and (3)
performance, programmability, and portability issues in modern GPUs, especially
those related to memory system resources.
