On Mon, Oct 31, 2016 at 06:38:52PM +0100, Sebastian Andrzej Siewior wrote: > On 2016-10-16 04:28:46 [-0700], Paul E. McKenney wrote: > > If the relevant maintainers are OK with that, I am OK with it as long > > as it is non-default (at least to begin with) and does not introduce > > additional Kconfig questions. My guess is that a boot parameter would > > work best, but something to discuss. > > Okay. For me to summary: > - we want rcu_normal_after_boot=1 on -RT via CONFIG_PREEMPT_RT_FULL That would be good. > - this makes synchronize_rcu_expedited() behave like > synchronize_rcu() and therefore I can drop all patches replacing > synchronize_rcu_expedited() with synchronize_rcu(). And this would be a benefit. ;-) > - optionally it has been requested to make synchronize_rcu() behave like > synchronize_rcu_expedited() on shutdown and kexec(). You can invoke rcu_unexpedite_gp() to force all subsequennt grace periods to be expedited, but you do need to clear rcu_normal for this to have effect. Right now, that means "WRITE_ONCE(rcu_normal, 0)", but I could easily supply a formal API if you would prefer. Which you probably would given that TINY_RCU doesn't have rcu_normal... > Did I miss understood / forgot something? It would not hurt to boot with rcu_expedited if boot speed is critical, but I don't know whether or not this should be enabled by default. Thanx, Paul > Sebastian > -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
