Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

From: Paul E. McKenney
Date: Sat Aug 23 2014 - 23:24:05 EST


On Sat, Aug 23, 2014 at 08:26:10PM -0400, Pranith Kumar wrote:
> On Sat, Aug 23, 2014 at 12:51 PM, Paul E. McKenney
> <paulmck@xxxxxxxxxxxxxxxxxx> wrote:
>
> > It might well! Another possibility is that the early_initcall function
> > doing the synchronize_rcu() is happening before the early_initcall
> > creating the RCU grace-period kthreads.
> >
> > Seems like we need to close both holes. Let's see how your patch works
> > for Amit, and I am testing a patch for the possible early_initcall
> > ordering issue.
>
> I checked the init call which is calling synchronize_rcu():
> subsys_initcall(pm_sysrq_init); this is being called after
> early_initcall.
>
> The order of initcalls is early, core, postcore, arch, subsys, fs,
> device, late. So I guess that is ok.
>
> I wonder why it was not showing up in 12.04. I have a dual boot. Will
> test it out and see if I can find something.

Me, I am wondering about 7,000 callbacks being registered during early
boot time. ;-)

Thanx, Paul

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