On Tue, 1 Sep 2020 at 19:42, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > On Tue, Sep 01, 2020 at 09:13:40AM -0700, Paul E. McKenney wrote: > > On Tue, Sep 01, 2020 at 05:50:14PM +0200, peterz@xxxxxxxxxxxxx wrote: > > > On Tue, Sep 01, 2020 at 09:44:17AM -0600, Lina Iyer wrote: > > > > > > > > > I could add RCU_NONIDLE for the calls to pm_runtime_put_sync_suspend() > > > > > > > > > and pm_runtime_get_sync() in psci_enter_domain_idle_state(). Perhaps > > > > > > > > > that's the easiest approach, at least to start with. > > > > > > > I think this would be nice. This should also cover the case, where PM domain > > > > power off notification callbacks call trace function internally. Right? > > > > > > That's just more crap for me to clean up later :-( > > > > > > trace_*_rcuidle() and RCU_NONIDLE() need to die, not proliferate. > > > > Moving the idle-entry boundary further in is good in any number of ways. > > But experience indicates that no matter how far you move it, there will > > be something complex further in. Unless you are pushing it all the way > > into all the arch-specific code down as far as it can possibly go? > > Not all; the simple cpuidle drivers should be good already. The more > complicated ones need some help. > > The patch provided earlier: > > https://lkml.kernel.org/r/20200901104206.GU1362448@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx > > should allow the complicated drivers to take over and DTRT. Don't get me wrong, I fully support your approach by moving the rcu_idle_enter() down as far as possible, but it seems to require more work than just adding a simple flag for the idle states. Lots of cpuidle drivers are using CPU_PM notifiers (grep for cpu_pm_enter and you will see) from their idlestates ->enter() callbacks. And for those we are already calling rcu_irq_enter_irqson|off() in cpu_pm_notify() when firing them. Kind regards Uffe
