On Friday, February 07, 2014 01:36:52 PM Preeti U Murthy wrote: > Some archs set the CPUIDLE_FLAG_TIMER_STOP flag for idle states in which the > local timers stop. The cpuidle_idle_call() currently handles such idle states > by calling into the broadcast framework so as to wakeup CPUs at their next > wakeup event. With the hrtimer mode of broadcast, the BROADCAST_ENTER call > into the broadcast frameowork can fail for archs that do not have an external > clock device to handle wakeups and the CPU in question has to thus be made > the stand by CPU. This patch handles such cases by failing the call into > cpuidle so that the arch can take some default action. The arch will certainly > not enter a similar idle state because a failed cpuidle call will also > implicitly > indicate that the broadcast framework has not registered this CPU to be woken > up. > Hence we are safe if we fail the cpuidle call. > > In the process move the functions that trace idle statistics just before and > after the entry and exit into idle states respectively. In other > scenarios where the call to cpuidle fails, we end up not tracing idle > entry and exit since a decision on an idle state could not be taken. Similarly > when the call to broadcast framework fails, we skip tracing idle statistics > because we are in no further position to take a decision on an alternative > idle state to enter into. > > Signed-off-by: Preeti U Murthy <pre...@linux.vnet.ibm.com>
Acked-by: Rafael J. Wysocki <rafael.j.wyso...@intel.com> > --- > > drivers/cpuidle/cpuidle.c | 14 ++++++++------ > 1 file changed, 8 insertions(+), 6 deletions(-) > > diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c > index a55e68f..8beb0f02 100644 > --- a/drivers/cpuidle/cpuidle.c > +++ b/drivers/cpuidle/cpuidle.c > @@ -140,12 +140,14 @@ int cpuidle_idle_call(void) > return 0; > } > > - trace_cpu_idle_rcuidle(next_state, dev->cpu); > - > broadcast = !!(drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP); > > - if (broadcast) > - clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu); > + if (broadcast && > + clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu)) > + return -EBUSY; > + > + > + trace_cpu_idle_rcuidle(next_state, dev->cpu); > > if (cpuidle_state_is_coupled(dev, drv, next_state)) > entered_state = cpuidle_enter_state_coupled(dev, drv, > @@ -153,11 +155,11 @@ int cpuidle_idle_call(void) > else > entered_state = cpuidle_enter_state(dev, drv, next_state); > > + trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu); > + > if (broadcast) > clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &dev->cpu); > > - trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu); > - > /* give the governor an opportunity to reflect on the outcome */ > if (cpuidle_curr_governor->reflect) > cpuidle_curr_governor->reflect(dev, entered_state); > > -- > To unsubscribe from this list: send the line "unsubscribe linux-pm" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
