D.4.3.1 Testing
Keywords: perfbook_html

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D.4.3.1 Testing

The preemptible RCU algorithm was tested with a two-stage grace period on weakly ordered POWER4 and POWER5 CPUs using rcutorture running for more than 24 hours on each machine, with 15M and 20M grace periods, respectively, and with no errors. Of course, this in no way proves that this algorithm is correct. At most, it shows either that these two machines were extremely lucky or that any bugs remaining in preemptible RCU have an extremely low probability of occurring. We therefore required additional assurance that this algorithm works, or, alternatively, identification of remaining bugs.

This task requires a conceptual approach, which is taken in the next section.