On 03/28/2013 09:10 PM, Srivatsa S. Bhat wrote: > On 03/22/2013 03:23 AM, Thomas Gleixner wrote: >> Signed-off-by: Thomas Gleixner <[email protected]> >> Cc: Benjamin Herrenschmidt <[email protected]> >> --- > [...] >> Index: linux-2.6/arch/powerpc/kernel/idle.c >> =================================================================== >> --- linux-2.6.orig/arch/powerpc/kernel/idle.c >> +++ linux-2.6/arch/powerpc/kernel/idle.c >> @@ -50,64 +50,30 @@ static int __init powersave_off(char *ar >> } >> __setup("powersave=off", powersave_off); >> >> -/* >> - * The body of the idle task. >> - */ >> -void cpu_idle(void) >> +void arch_cpu_idle(void) >> { >> - set_thread_flag(TIF_POLLING_NRFLAG); >> - while (1) { >> - tick_nohz_idle_enter(); >> - rcu_idle_enter(); >> - >> - while (!need_resched() && !cpu_should_die()) { >> - ppc64_runlatch_off(); >> - >> - if (ppc_md.power_save) { >> - clear_thread_flag(TIF_POLLING_NRFLAG); >> - /* >> - * smp_mb is so clearing of TIF_POLLING_NRFLAG >> - * is ordered w.r.t. need_resched() test. >> - */ >> - smp_mb(); >> - local_irq_disable(); >> - >> - /* Don't trace irqs off for idle */ >> - stop_critical_timings(); >> - >> - /* check again after disabling irqs */ >> - if (!need_resched() && !cpu_should_die()) >> - ppc_md.power_save(); >> - >> - start_critical_timings(); >> - >> - /* Some power_save functions return with >> - * interrupts enabled, some don't. >> - */ >> - if (irqs_disabled()) >> - local_irq_enable(); >> - set_thread_flag(TIF_POLLING_NRFLAG); >> - >> - } else { >> - /* >> - * Go into low thread priority and possibly >> - * low power mode. >> - */ >> - HMT_low(); >> - HMT_very_low(); >> - } >> - } >> - >> - HMT_medium(); >> - ppc64_runlatch_on(); >> - rcu_idle_exit(); >> - tick_nohz_idle_exit(); >> - if (cpu_should_die()) { >> - sched_preempt_enable_no_resched(); >> - cpu_die(); >> - } >> - schedule_preempt_disabled(); >> + ppc64_runlatch_off(); >> + >> + if (ppc_md.power_save) { >> + ppc_md.power_save(); >> + /* >> + * Some power_save functions return with >> + * interrupts enabled, some don't. >> + */ >> + if (irqs_disabled()) >> + local_irq_enable(); >> + } else { >> + local_irq_enable(); >> + /* >> + * Go into low thread priority and possibly >> + * low power mode. >> + */ >> + HMT_low(); >> + HMT_very_low(); >> } >> + >> + HMT_medium(); >> + ppc64_runlatch_on(); >> } >>
The below patch is essential to get hotplug working on POWER. With that, generic idle loop works fine for PSERIES. Tested-by: Deepthi Dharwar <[email protected]> > > The call to cpu_die() seems to be missing. And considering this commit, > > commit a7c2bb8279d20d853e43c34584eaf2b039de8026 > Author: Signed-off-by: Darren Hart <[email protected]> > Date: Wed Aug 4 18:28:33 2010 +0000 > > powerpc: Re-enable preemption before cpu_die() > > we need to call it with preempt enabled. So how about folding the > following diff with this patch? > > > diff --git a/arch/powerpc/kernel/idle.c b/arch/powerpc/kernel/idle.c > index b751baa..e434fb9 100644 > --- a/arch/powerpc/kernel/idle.c > +++ b/arch/powerpc/kernel/idle.c > @@ -33,11 +33,6 @@ > #include <asm/runlatch.h> > #include <asm/smp.h> > > -#ifdef CONFIG_HOTPLUG_CPU > -#define cpu_should_die() cpu_is_offline(smp_processor_id()) > -#else > -#define cpu_should_die() 0 > -#endif > > unsigned long cpuidle_disable = IDLE_NO_OVERRIDE; > EXPORT_SYMBOL(cpuidle_disable); > @@ -50,6 +45,12 @@ static int __init powersave_off(char *arg) > } > __setup("powersave=off", powersave_off); > > +void arch_cpu_idle_dead(void) > +{ > + sched_preempt_enable_no_resched(); > + cpu_die(); > +} > + > void arch_cpu_idle(void) > { > ppc64_runlatch_off(); > > > Regards, > Srivatsa S. Bhat > -- 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/
