Keywords: perfbook_html

#### 10.3.2.1.6 RCU Grace Periods Extend for Many Milliseconds

With the exception of QRCU and several of the ``toy'' RCU implementations described in Section , RCU grace periods extend for multiple milliseconds. Although there are a number of techniques to render such long delays harmless, including use of the asynchronous interfaces where available (call_rcu() and call_rcu_bh()), this situation is a major reason for the rule of thumb that RCU be used in read-mostly situations.