On 11/07/2014 08:01 PM, Daniel Lezcano wrote: > The poll function is called when a timer expired or if we force to poll when > the cpu_idle_force_poll option is set. > > The poll function does: > > local_irq_enable(); > while (!tif_need_resched()) > cpu_relax(); > > This default poll function suits for the x86 arch because its rep; nop; > hardware power optimization. But on other archs, this optimization does not > exists and we are not saving power. The arch specific bits may want to > optimize this loop by adding their own optimization. > > Give an opportunity to the different platform to specify their own polling > loop by adding a weak cpu_idle_poll_loop function. > > Signed-off-by: Daniel Lezcano <[email protected]> > --- > kernel/sched/idle.c | 29 +++++++++++++++++------------ > 1 file changed, 17 insertions(+), 12 deletions(-) > > diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c > index c47fce7..ea65bbae 100644 > --- a/kernel/sched/idle.c > +++ b/kernel/sched/idle.c > @@ -42,18 +42,6 @@ static int __init cpu_idle_nopoll_setup(char *__unused) > __setup("hlt", cpu_idle_nopoll_setup); > #endif > > -static inline int cpu_idle_poll(void) > -{ > - rcu_idle_enter(); > - trace_cpu_idle_rcuidle(0, smp_processor_id()); > - local_irq_enable(); > - while (!tif_need_resched()) > - cpu_relax(); > - trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id()); > - rcu_idle_exit(); > - return 1; > -} > - > /* Weak implementations for optional arch specific functions */ > void __weak arch_cpu_idle_prepare(void) { } > void __weak arch_cpu_idle_enter(void) { } > @@ -65,6 +53,23 @@ void __weak arch_cpu_idle(void) > local_irq_enable(); > } > > +void __weak arch_cpu_idle_poll(void) > +{ > + local_irq_enable(); > + while (!tif_need_resched()) > + cpu_relax(); > +} > + > +static inline int cpu_idle_poll(void) > +{ > + rcu_idle_enter(); > + trace_cpu_idle_rcuidle(0, smp_processor_id()); > + arch_cpu_idle_poll(); > + trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id()); > + rcu_idle_exit(); > + return 1; > +} > + > /** > * cpuidle_idle_call - the main idle function > * >
Thanks Daniel! Reviewed-by: Preeti U. Murthy <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
