D.2.7.9 Online a CPU
Keywords: perfbook_html

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D.2.7.9 Online a CPU

CPU-online events cause rcu_cpu_notify() to invoke rcu_online_cpu(), which initializes the incoming CPU's dynticks state, and then invokes rcu_init_percpu_data() to initialize the incoming CPU's rcu_data structure, and also to set this CPU's bits (again protected by the global ->onofflock) so that future grace periods will wait for a quiescent state from this CPU. Finally, rcu_online_cpu() sets up the RCU softirq vector for this CPU.

Quick Quiz D.17: Given all these acquisitions of the global ->onofflock, won't there be horrible lock contention when running with thousands of CPUs? End Quick Quiz

Quick Quiz D.18: Why not simplify the code by merging the detection of dyntick-idle CPUs with that of offline CPUs? End Quick Quiz