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Date: Sat, 23 May 2009 12:44:58 +0200 From: Peter Zijlstra <a.p.zijlstra@...llo.nl> To: venkatesh.pallipadi@...el.com Cc: mingo@...e.hu, tglx@...utronix.de, hpa@...or.com, linux-kernel@...r.kernel.org, lenb@...nel.org, shaohua.li@...el.com, svaidy@...ux.vnet.ibm.com Subject: Re: [patch 1/2] x86: Add pm_play_dead funcptr to power-efficiently offline CPUs On Fri, 2009-05-22 at 16:19 -0700, venkatesh.pallipadi@...el.com wrote: > plain text document attachment > (0001-x86-Add-pm_play_dead-funcptr-to-power-efficiently-o.patch) > Add a funcptr pm_play_dead (similar to pm_idle) that can take > the offline CPUs to the most power efficient idle state. > > This patch just adds the func pointer. The pointer will get initialized > by patch that follows. Since the pm_idle function pointer has given us so much grief, I don't think its wise to repeat that particular disaster. I'd much rather see a framework where idle functions can be registered, and selected from based on criteria such as wakeup latency as provided by the pm_qos stuff, and power saving. This framework should be shared between hotplug-idle and the regular idle routines. Hotplug would of course not care about things like wakeup latency and might therefore pick another idle routine. > Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@...el.com> > --- > arch/x86/include/asm/smp.h | 2 ++ > arch/x86/kernel/smpboot.c | 7 ++++++- > 2 files changed, 8 insertions(+), 1 deletions(-) > > diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h > index 19e0d88..0388b81 100644 > --- a/arch/x86/include/asm/smp.h > +++ b/arch/x86/include/asm/smp.h > @@ -148,6 +148,8 @@ static inline int num_booting_cpus(void) > { > return cpumask_weight(cpu_callout_mask); > } > + > +extern void (*pm_play_dead)(void); > #endif /* CONFIG_SMP */ > > extern unsigned disabled_cpus __cpuinitdata; > diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c > index 58d24ef..4f8af6a 100644 > --- a/arch/x86/kernel/smpboot.c > +++ b/arch/x86/kernel/smpboot.c > @@ -1195,6 +1195,8 @@ __init void prefill_possible_map(void) > nr_cpu_ids = possible; > } > > +void (*pm_play_dead)(void) = NULL; > + > #ifdef CONFIG_HOTPLUG_CPU > > static void remove_siblinginfo(int cpu) > @@ -1313,7 +1315,10 @@ void play_dead_common(void) > void native_play_dead(void) > { > play_dead_common(); > - wbinvd_halt(); > + if (pm_play_dead) > + pm_play_dead(); > + else > + wbinvd_halt(); > } > > #else /* ... !CONFIG_HOTPLUG_CPU */ > -- > 1.6.0.6 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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