Compulsory Misses: from cold start, where data has never been loaded.
Capacity Misses: reload of a line that was held before,
Consistency Misses:eviction since another core needs the line exclusively.
Cache hit ratios are commonly estimated with the formula from Che is applied by default [8].
A naive cache model that neglects temporal locality would assume random arrivals and be parameterised only by the ratio of cache capacity to number of cacheable lines.
Che’s model instead is phrased in terms of the additional modelling parameter, the mean eviction time, N_C , which is the average number of operations before C different lines are requested where C is the cache capacity. This assumes sufficient number of ways to avoid the Birthday Paradox.
[8] V. Martina, M. Garetto, and E. Leonardi, “A unified approach to the performance analysis of caching systems,” in INFOCOM, 2014 Proceedings IEEE, April 2014, pp. 2040–2048.
| 8: (C) 2012-16, DJ Greaves, University of Cambridge, Computer Laboratory. |