On Wed, Oct 12, 2016 at 12:49:56PM -0400, Luiz Capitulino wrote: > On Wed, 12 Oct 2016 11:21:14 -0500 > Julia Cartwright <julia@xxxxxx> wrote: > > > On Wed, Oct 12, 2016 at 11:12:51AM -0400, Luiz Capitulino wrote: > > > Hi, > > > > > > We have the following patch applied to the RT tree: > > > > > > commit a9d3cc781a3306bfa332fa7cb6134b70696058d5 > > > Author: Josh Cartwright <joshc@xxxxxx> > > > Date: Tue Oct 27 07:31:53 2015 -0500 > > > > > > net: Make synchronize_rcu_expedited() conditional on !RT_FULL > > > > > > However, as noted by Michael, making rcu_normal=1 default in the > > > RT kernel should have the same effect (ie. not calling > > > synchronize_sched_expedited()). > > > > > > So, honest question, is there a reason not to: > > > > > > 1. Drop the patch above > > > 2. Make rcu_normal=1 default? > > > > I think this is probably a cleaner way to fix the problems which > > motivated this patch in the first place. In my defense, the above patch > > predates rcu_normal :). > > No need to defend yourself! We debugged this very spike in one of > our kernels that don't have rcu_normal. We decided to do exactly > what you're doing before looking at upstream. Your patch helped > us confirm that we were in the right track. Great! Glad I could help in some way! > > Something like this, perhaps? > > Looks good, but (honest question) what does it buy us using > rcu_normal_after_boot vs rcu_normal? Is the boot process > improved someway? That's the idea, although I don't have data to show much it actually buys us. > As long as we're rcu_normal=1 before launching user-space, > this should be fine. Agreed. Thanks, Julia -- 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
