| Message ID | 20140206055036.4595.86947.stgit@preeti (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Thursday, February 06, 2014 11:20:37 AM 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 <preeti@linux.vnet.ibm.com> The cpuidle changes in this patch look reasonable to me, but I guess you'd like it to go in via tip along with the rest of the series, so Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > --- > > drivers/cpuidle/cpuidle.c | 38 +++++++++++++++++++++++--------------- > 1 file changed, 23 insertions(+), 15 deletions(-) > > diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c > index a55e68f..8f42033 100644 > --- a/drivers/cpuidle/cpuidle.c > +++ b/drivers/cpuidle/cpuidle.c > @@ -117,15 +117,19 @@ int cpuidle_idle_call(void) > { > struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices); > struct cpuidle_driver *drv; > - int next_state, entered_state; > - bool broadcast; > + int next_state, entered_state, ret = 0; > + bool broadcast = false; > > - if (off || !initialized) > - return -ENODEV; > + if (off || !initialized) { > + ret = -ENODEV; > + goto out; > + } > > /* check if the device is ready */ > - if (!dev || !dev->enabled) > - return -EBUSY; > + if (!dev || !dev->enabled) { > + ret = -EBUSY; > + goto out; > + } > > drv = cpuidle_get_cpu_driver(dev); > > @@ -137,15 +141,18 @@ int cpuidle_idle_call(void) > if (cpuidle_curr_governor->reflect) > cpuidle_curr_governor->reflect(dev, next_state); > local_irq_enable(); > - return 0; > + goto out; > } > > - 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) { > + ret = clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu); > + if (ret) > + goto out; > + } > + > + 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, > @@ -153,16 +160,17 @@ int cpuidle_idle_call(void) > else > entered_state = cpuidle_enter_state(dev, drv, next_state); > > - 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); > > - return 0; > +out: if (broadcast) > + clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &dev->cpu); > + > + > + return ret; > } > > /** > > -- > To unsubscribe from this list: send the line "unsubscribe linux-pm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index a55e68f..8f42033 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -117,15 +117,19 @@ int cpuidle_idle_call(void) { struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices); struct cpuidle_driver *drv; - int next_state, entered_state; - bool broadcast; + int next_state, entered_state, ret = 0; + bool broadcast = false; - if (off || !initialized) - return -ENODEV; + if (off || !initialized) { + ret = -ENODEV; + goto out; + } /* check if the device is ready */ - if (!dev || !dev->enabled) - return -EBUSY; + if (!dev || !dev->enabled) { + ret = -EBUSY; + goto out; + } drv = cpuidle_get_cpu_driver(dev); @@ -137,15 +141,18 @@ int cpuidle_idle_call(void) if (cpuidle_curr_governor->reflect) cpuidle_curr_governor->reflect(dev, next_state); local_irq_enable(); - return 0; + goto out; } - 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) { + ret = clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu); + if (ret) + goto out; + } + + 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, @@ -153,16 +160,17 @@ int cpuidle_idle_call(void) else entered_state = cpuidle_enter_state(dev, drv, next_state); - 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); - return 0; +out: if (broadcast) + clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &dev->cpu); + + + return ret; } /**
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 <preeti@linux.vnet.ibm.com> --- drivers/cpuidle/cpuidle.c | 38 +++++++++++++++++++++++--------------- 1 file changed, 23 insertions(+), 15 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html