Inclusive Cost Attribution for Cache Use Profiling

Abstract

For performance analysis tools to be useful, they need to show the relation of detected bottlenecks to source code. To this end, it often makes sense to use the instruction triggering a problematic event. However for cache line utilization, information on usage is only available at eviction time, but may be better attributed to the instruction which loaded the line. Such attribution is impossible with current processor hardware. Callgrind, a cache simulator part of the open-source Valgrind tool, can do this. However, it only provides Self Costs. In this paper, we extend the cost attribution of cache use metrics to inclusive costs which helps for top-down analysis of complex workloads. The technique can be used for all event types where collected metrics should to be attributed to instructions executing earlier in a program run to be useful.