Software Lockout Mitigation
To reduce the performance degradation of software lockout to reasonable levels (L/E between 0.05 and 0.1), the kernel and/or the operating system must be designed accordingly. Conceptually, the most valid solution is to decompose each kernel data structure in smaller independent substructures, having each a shorter elaboration time. This allows more than one CPU to access the original data structure.
Many uniprocessor systems with hierarchical protection domains, have been estimated to spend up to 50% of the time performing "supervisor mode" operations. If such systems were adapted for multiprocessing by setting a lock at any access to "supervisor state", L/E would easily be greater than 1, resulting in a system with the same bandwidth of the uniprocessor despite the number of CPUs.
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