Re: [RFC] vmstat: Avoid waking up idle-cpu to service shepherd work

[Peter Zijlstra]

On Sat, Mar 28, 2015 at 02:44:57PM +0100, Peter Zijlstra wrote:
> > Now there are few issues I see here (Sorry if they are all imaginary):
> > - In case a timer re-arms itself from its handler and is migrated from CPU A to B, what
> >   happens if the re-armed timer fires before the first handler finishes ? i.e. timer->fn()
> >   hasn't finished running on CPU A and it has fired again on CPU B. Wouldn't this expose
> >   us to a lot of other problems? It wouldn't be serialized to itself anymore ?
> 
> What I said above.

What I didn't say, but had thought of is that __run_timer() should skip
any timer that has RUNNING set -- for obvious reasons :-)
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