@TechReport{	  it:2012-003,
  author	= {David Ekl{\"o}v and Nikos Nikoleris and David
		  Black-Schaffer and Erik Hagersten},
  title		= {Design and Evaluation of the {B}andwidth {B}andit},
  institution	= {Department of Information Technology, Uppsala University},
  department	= {Division of Computer Systems},
  year		= {2012},
  number	= {2012-003},
  month		= feb,
  abstract	= {Applications that are co-scheduled on a multicore compete
		  for shared resources, such as cache capacity and memory
		  bandwidth. The performance degradation resulting from this
		  contention can be substantial, which makes it important to
		  effectively manage these shared resources. This, however,
		  requires an understanding of how applications are impacted
		  by such contention.
		  
		  While the effects of contention for cache capacity have
		  been extensively studied, less is known about the effects
		  of contention for memory bandwidth. This is in large due to
		  its complex nature, as sensitivity to bandwidth contention
		  depends on bottlenecks at several levels of the
		  memory-system, the interaction and locality properties of
		  the application~s access stream. This paper explores the
		  contention effects of increased latency and decreased
		  memory parallelism at different points in the memory
		  hierarchy, both of which cause decreases in available
		  bandwidth. To understand the impact of such contention on
		  applications, it also presents a method whereby an
		  application~s overall sensitivity to different degrees of
		  bandwidth contention can be directly measured. This method
		  is used to demonstrate the varying contention sensitivity
		  across a selection of benchmarks, and explains why some of
		  them experience substantial slowdowns long before the
		  overall memory bandwidth saturates. }
}