Messages in this thread |  | | | Subject | Re: [PATCH RFC tip/core/rcu] accelerate grace period if last non-dynticked CPU | | From | Steven Rostedt <> | | Date | Mon, 25 Jan 2010 10:08:17 -0500 |
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On Mon, 2010-01-25 at 20:28 +0800, Lai Jiangshan wrote: > Paul E. McKenney wrote:
> > + /* Don't bother unless we are the last non-dyntick-idle CPU. */ > > + for_each_cpu(thatcpu, nohz_cpu_mask) > > + if (thatcpu != cpu) > > + return rcu_needs_cpu_quick_check(cpu); > > The comment and the code are not the same, I think. >
I once heard this quote, but I don't know who said it:
"If the comment and the code do not match, they probably are both wrong"
Anyway, you are correct, the comment does not match, but I think the code is wrong. The code returns if any cpu is in non-dyntick-idle state. Reading the change log, that looks wrong. Perhaps this is what was needed:
for_each_online_cpu(thatcpu) { if (thatcpu != cpu && !cpumask_test_cpu(thatcpu, nohz_cpu_mask) return rcu_needs_cpu_quick_check(cpu); } -- Steve
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