| Message ID | 1390802904-28399-7-git-send-email-nicolas.pitre@linaro.org |
|---|---|
| State | New |
| Headers | show |
On 01/27/2014 07:08 AM, Nicolas Pitre wrote: > The core idle loop now takes care of it. However a few things need > checking: > > - Invocation of cpuidle_idle_call() in pseries_lpar_idle() happened > through arch_cpu_idle() and was therefore always preceded by a call > to ppc64_runlatch_off(). To preserve this property now that > cpuidle_idle_call() is invoked directly from core code, a call to > ppc64_runlatch_off() has been added to idle_loop_prolog() in > platforms/pseries/processor_idle.c. > > - Similarly, cpuidle_idle_call() was followed by ppc64_runlatch_off() > so a call to the later has been added to idle_loop_epilog(). > > - And since arch_cpu_idle() always made sure to re-enable IRQs if they > were not enabled, this is now > done in idle_loop_epilog() as well. > > The above was made in order to keep the execution flow close to the > original. I don't know if that was strictly necessary. Someone well > aquainted with the platform details might find some room for possible > optimizations. > > Signed-off-by: Nicolas Pitre <nico@linaro.org> Added Preeti U Murthy as recipient. > --- > arch/powerpc/platforms/pseries/processor_idle.c | 5 ++++ > arch/powerpc/platforms/pseries/setup.c | 34 ++++++++++--------------- > 2 files changed, 19 insertions(+), 20 deletions(-) > > diff --git a/arch/powerpc/platforms/pseries/processor_idle.c b/arch/powerpc/platforms/pseries/processor_idle.c > index a166e38bd6..72ddfe3d2f 100644 > --- a/arch/powerpc/platforms/pseries/processor_idle.c > +++ b/arch/powerpc/platforms/pseries/processor_idle.c > @@ -33,6 +33,7 @@ static struct cpuidle_state *cpuidle_state_table; > > static inline void idle_loop_prolog(unsigned long *in_purr) > { > + ppc64_runlatch_off(); > *in_purr = mfspr(SPRN_PURR); > /* > * Indicate to the HV that we are idle. Now would be > @@ -49,6 +50,10 @@ static inline void idle_loop_epilog(unsigned long in_purr) > wait_cycles += mfspr(SPRN_PURR) - in_purr; > get_lppaca()->wait_state_cycles = cpu_to_be64(wait_cycles); > get_lppaca()->idle = 0; > + > + if (irqs_disabled()) > + local_irq_enable(); > + ppc64_runlatch_on(); > } > > static int snooze_loop(struct cpuidle_device *dev, > diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c > index c1f1908587..7604c19d54 100644 > --- a/arch/powerpc/platforms/pseries/setup.c > +++ b/arch/powerpc/platforms/pseries/setup.c > @@ -39,7 +39,6 @@ > #include <linux/irq.h> > #include <linux/seq_file.h> > #include <linux/root_dev.h> > -#include <linux/cpuidle.h> > #include <linux/of.h> > #include <linux/kexec.h> > > @@ -356,29 +355,24 @@ early_initcall(alloc_dispatch_log_kmem_cache); > > static void pseries_lpar_idle(void) > { > - /* This would call on the cpuidle framework, and the back-end pseries > - * driver to go to idle states > + /* > + * Default handler to go into low thread priority and possibly > + * low power mode by cedeing processor to hypervisor > */ > - if (cpuidle_idle_call()) { > - /* On error, execute default handler > - * to go into low thread priority and possibly > - * low power mode by cedeing processor to hypervisor > - */ > > - /* Indicate to hypervisor that we are idle. */ > - get_lppaca()->idle = 1; > + /* Indicate to hypervisor that we are idle. */ > + get_lppaca()->idle = 1; > > - /* > - * Yield the processor to the hypervisor. We return if > - * an external interrupt occurs (which are driven prior > - * to returning here) or if a prod occurs from another > - * processor. When returning here, external interrupts > - * are enabled. > - */ > - cede_processor(); > + /* > + * Yield the processor to the hypervisor. We return if > + * an external interrupt occurs (which are driven prior > + * to returning here) or if a prod occurs from another > + * processor. When returning here, external interrupts > + * are enabled. > + */ > + cede_processor(); > > - get_lppaca()->idle = 0; > - } > + get_lppaca()->idle = 0; > } > > /* >
diff --git a/arch/powerpc/platforms/pseries/processor_idle.c b/arch/powerpc/platforms/pseries/processor_idle.c index a166e38bd6..72ddfe3d2f 100644 --- a/arch/powerpc/platforms/pseries/processor_idle.c +++ b/arch/powerpc/platforms/pseries/processor_idle.c @@ -33,6 +33,7 @@ static struct cpuidle_state *cpuidle_state_table; static inline void idle_loop_prolog(unsigned long *in_purr) { + ppc64_runlatch_off(); *in_purr = mfspr(SPRN_PURR); /* * Indicate to the HV that we are idle. Now would be @@ -49,6 +50,10 @@ static inline void idle_loop_epilog(unsigned long in_purr) wait_cycles += mfspr(SPRN_PURR) - in_purr; get_lppaca()->wait_state_cycles = cpu_to_be64(wait_cycles); get_lppaca()->idle = 0; + + if (irqs_disabled()) + local_irq_enable(); + ppc64_runlatch_on(); } static int snooze_loop(struct cpuidle_device *dev, diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c index c1f1908587..7604c19d54 100644 --- a/arch/powerpc/platforms/pseries/setup.c +++ b/arch/powerpc/platforms/pseries/setup.c @@ -39,7 +39,6 @@ #include <linux/irq.h> #include <linux/seq_file.h> #include <linux/root_dev.h> -#include <linux/cpuidle.h> #include <linux/of.h> #include <linux/kexec.h> @@ -356,29 +355,24 @@ early_initcall(alloc_dispatch_log_kmem_cache); static void pseries_lpar_idle(void) { - /* This would call on the cpuidle framework, and the back-end pseries - * driver to go to idle states + /* + * Default handler to go into low thread priority and possibly + * low power mode by cedeing processor to hypervisor */ - if (cpuidle_idle_call()) { - /* On error, execute default handler - * to go into low thread priority and possibly - * low power mode by cedeing processor to hypervisor - */ - /* Indicate to hypervisor that we are idle. */ - get_lppaca()->idle = 1; + /* Indicate to hypervisor that we are idle. */ + get_lppaca()->idle = 1; - /* - * Yield the processor to the hypervisor. We return if - * an external interrupt occurs (which are driven prior - * to returning here) or if a prod occurs from another - * processor. When returning here, external interrupts - * are enabled. - */ - cede_processor(); + /* + * Yield the processor to the hypervisor. We return if + * an external interrupt occurs (which are driven prior + * to returning here) or if a prod occurs from another + * processor. When returning here, external interrupts + * are enabled. + */ + cede_processor(); - get_lppaca()->idle = 0; - } + get_lppaca()->idle = 0; } /*
The core idle loop now takes care of it. However a few things need checking: - Invocation of cpuidle_idle_call() in pseries_lpar_idle() happened through arch_cpu_idle() and was therefore always preceded by a call to ppc64_runlatch_off(). To preserve this property now that cpuidle_idle_call() is invoked directly from core code, a call to ppc64_runlatch_off() has been added to idle_loop_prolog() in platforms/pseries/processor_idle.c. - Similarly, cpuidle_idle_call() was followed by ppc64_runlatch_off() so a call to the later has been added to idle_loop_epilog(). - And since arch_cpu_idle() always made sure to re-enable IRQs if they were not enabled, this is now done in idle_loop_epilog() as well. The above was made in order to keep the execution flow close to the original. I don't know if that was strictly necessary. Someone well aquainted with the platform details might find some room for possible optimizations. Signed-off-by: Nicolas Pitre <nico@linaro.org> --- arch/powerpc/platforms/pseries/processor_idle.c | 5 ++++ arch/powerpc/platforms/pseries/setup.c | 34 ++++++++++--------------- 2 files changed, 19 insertions(+), 20 deletions(-)