Re: [PATCH 6/9] PPC: remove redundant cpuidle_idle_call()
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 n...@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;
}
/*
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Re: [PATCH 6/9] PPC: remove redundant cpuidle_idle_call()
Hi Nicolas,
On 01/27/2014 11:38 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 n...@linaro.org
---
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;
}
/*
Reviewed-by: Preeti U Murthy pre...@linux.vnet.ibm.com
The consequence of this would be for other Power platforms like PowerNV,
we will need to invoke ppc_runlatch_off() and ppc_runlatch_on() in each
of the idle routines since the idle_loop_prologue() and
idle_loop_epilogue() are not invoked by them, but we will take care of this.
Regards
Preeti U Murthy
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