MOESIL: A Cache Coherency Protocol for Locked Mixed Criticality L1 Data Cache

The tremendous needs of computing power and predictive timing behaviours of modern systems bring revolutionary changes in memory subsystem architecture. One such improvement is the usage of locked caches to have predictive execution time. The existing cache coherence protocols such as MESI, MOSI, MOESI, and MESIF lack a comprehensive approach for handling coherency in locked caches. This work proposes MOESIL, an enhanced version of MOESI to increase the data consistency of locked caches. Experimental evaluations using splash-2 benchmark programs on CACTI 5.3 and CACOSIM simulator substantiate the suitability of MOESIL protocol for locked caches in multi-core mixed criticality systems to honour the deadline of high criticality jobs. It is observed that MOESIL protocol reduces the miss rate by 2.89% with a comparable energy consumption over MOESI protocol.