Messages in this thread | | | Date | Wed, 12 Feb 2014 13:37:55 +0100 | From | Daniel Lezcano <> | Subject | Re: [PATCH 1/5] idle/cpuidle: Split cpuidle_idle_call main function into smaller functions |
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On 02/12/2014 11:38 AM, Preeti U Murthy wrote: > Hi Daniel, > > On 02/11/2014 08:41 PM, Daniel Lezcano wrote: >> In order to allow better integration between the cpuidle framework and the >> scheduler, reducing the distance between these two sub-components will >> facilitate this integration by moving part of the cpuidle code in the idle >> task file and, because idle.c is in the sched directory, we have access to >> the scheduler's private structures. >> >> This patch splits the cpuidle_idle_call main entry function into 3 calls >> to a newly added API: >> 1. select the idle state >> 2. enter the idle state >> 3. reflect the idle state >> >> The cpuidle_idle_call calls these three functions to implement the main >> idle entry function. >> >> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> >> --- >> drivers/cpuidle/cpuidle.c | 102 ++++++++++++++++++++++++++++++++------------- >> include/linux/cpuidle.h | 14 +++++++ >> 2 files changed, 87 insertions(+), 29 deletions(-) >> >> diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c >> index a55e68f..172ab6a 100644 >> --- a/drivers/cpuidle/cpuidle.c >> +++ b/drivers/cpuidle/cpuidle.c >> @@ -108,6 +108,71 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv, >> } >> >> /** >> + * cpuidle_select - ask the cpuidle framework to choose an idle state >> + * >> + * @drv: the cpuidle driver >> + * @dev: the cpuidle device >> + * >> + * Returns the index of the idle state. On error it returns: >> + * -NODEV : the cpuidle framework is not available >> + * -EBUSY : the cpuidle framework is not initialized >> + */ >> +int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) >> +{ >> + if (off || !initialized) >> + return -ENODEV; >> + >> + if (!drv || !dev || !dev->enabled) >> + return -EBUSY; > > I would suggest moving the above two conditions under another function, > cpuidle_enabled() maybe? The reason is, cpuidle_select() indicates that, > it is invoked to select an idle state. While you are expecting this > function to return an idle state, it seems counter-intuitive to return a > ENODEV/EBUSY. This function is expected to be a call into the governor > specific code and the same function should not be used to verify if > cpuidle is enabled/not IMHO.
Yes, I fully agree. I will fix that.
>> + >> + return cpuidle_curr_governor->select(drv, dev); >> +} >> + >> +/** >> + * cpuidle_enter - enter into the specified idle state >> + * >> + * @drv: the cpuidle driver tied with the cpu >> + * @dev: the cpuidle device >> + * @index: the index in the idle state table >> + * >> + * Returns the index in the idle state, < 0 in case of error. >> + * The error code depends on the backend driver >> + */ >> +int cpuidle_enter(struct cpuidle_driver *drv, struct cpuidle_device *dev, >> + int index) >> +{ >> + int entered_state; >> + bool broadcast = !!(drv->states[index].flags & CPUIDLE_FLAG_TIMER_STOP); >> + >> + if (broadcast) >> + clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu); >> + >> + if (cpuidle_state_is_coupled(dev, drv, index)) >> + entered_state = cpuidle_enter_state_coupled(dev, drv, index); >> + else >> + entered_state = cpuidle_enter_state(dev, drv, index); >> + >> + if (broadcast) >> + clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &dev->cpu); > > The tip tree, timers/core branch has the patch, > tick: Introduce hrtimer based broadcast. In the problem scenario that > this patchset is addressing, the call to broadcast framework may return > an error indicating that the idle state in question cannot be entered > into. I wanted to bring it to your notice, so that early on you can take > care of this. You will need to add code below in the invocation of > cpuidle_enter() to verify if the idle state was entered into or not. If > it was not, then you will need to skip tracing and reflecting of the > idle state and directly exit the cpuidle loop with a failed status.
Ok.
Thanks !
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