Messages in this thread | | | Date | Tue, 30 Mar 2010 17:43:33 +0800 | From | Lai Jiangshan <> | Subject | Re: [PATCH] rcu: don't call rcu_preempt_note_context_switch() in rcu_check_callbacks() |
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Paul E. McKenney wrote: > On Mon, Mar 29, 2010 at 10:47:59AM +0800, Lai Jiangshan wrote: >> Content-Type: text/plain; charset=UTF-8 >> Content-Transfer-Encoding: 7bit >> >> >> Even though in user mode or idle mode, rcu_check_callbacks() is not >> context switch, so we don't call rcu_preempt_note_context_switch() >> in rcu_check_callbacks(). >> >> Though there is no harm that calls rcu_preempt_note_context_switch() >> in rcu_check_callbacks(), but it is waste. >> >> rcu_check_callbacks() >> rcu_sched_qs() >> rcu_preempt_note_context_switch() >> Now, ->rcu_read_lock_nesting == 0, so we just calls >> rcu_preempt_qs(), but, rcu_preempt_check_callbacks() >> will call it again and set the ->rcu_read_unlock_special >> correct again. >> >> So let rcu_preempt_check_callbacks() handle things for us. > > Nice!!! > > But how about naming the new function that invokes > rcu_preempt_note_context_switch() something like > rcu_sched_note_context_switch(), and then leaving the > name of rcu_sched_qs() the same (rather than changing > it to __rcu_sched_qs(), as below)? > > This way, the names clearly call out what the function > is doing. >
If I understand right, it will become this:
schedule() / run_ksoftirqd() / rcu_needs_cpu() rcu_sched_note_context_switch() rcu_sched_qs() rcu_preempt_note_context_switch()
Right?
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