A COMPARISON OF TRACE-SAMPLING TECHNIQUES FOR MULTI-MEGABYTE CACHES

This paper compares the trace-sampling techniques of set sampling and time sampling. Using the multi-billion-reference traces of Borg et al. , we apply both techniques to multi-megabyte caches, where sampling is most valuable. We evaluate whether either technique meets a 10% sampl ing goal: a method meets this goal if, at least 90% of the time, it es timates the trace's true misses per instruction with less-than-or-equa l-to 10% relative error using less-than-or-equal-to 10% of the trace. Results for these traces and caches show that set sampling meets the 1 0% sampling goal, while time sampling does not. We also find that cold -start bias in time samples is most effectively reduced by the techniq ue of Wood et al. Nevertheless, overcoming cold-start bias requires te ns of millions of consecutive references.