2023-10-18 16:41:35

by Srikar Dronamraju

Subject: [PATCH v2 3/6] powerpc/smp: Move shared_processor static key to smp.h

The ability to detect if the system is running in a shared processor
mode is helpful in few more generic cases not just in
paravirtualization.
For example: At boot time, different scheduler/ topology flags may be
set based on the processor mode. Hence move it to a more generic file.

Signed-off-by: Srikar Dronamraju <[email protected]>
---
arch/powerpc/include/asm/paravirt.h | 12 ------------
arch/powerpc/include/asm/smp.h | 14 ++++++++++++++
2 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/arch/powerpc/include/asm/paravirt.h b/arch/powerpc/include/asm/paravirt.h
index 0372b0093f72..cf83e837a571 100644
--- a/arch/powerpc/include/asm/paravirt.h
+++ b/arch/powerpc/include/asm/paravirt.h
@@ -15,13 +15,6 @@
#include <asm/kvm_guest.h>
#include <asm/cputhreads.h>

-DECLARE_STATIC_KEY_FALSE(shared_processor);
-
-static inline bool is_shared_processor(void)
-{
- return static_branch_unlikely(&shared_processor);
-}
-
#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
extern struct static_key paravirt_steal_enabled;
extern struct static_key paravirt_steal_rq_enabled;
@@ -77,11 +70,6 @@ static inline bool is_vcpu_idle(int vcpu)
return lppaca_of(vcpu).idle;
}
#else
-static inline bool is_shared_processor(void)
-{
- return false;
-}
-
static inline u32 yield_count_of(int cpu)
{
return 0;
diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
index aaaa576d0e15..08631b2a4528 100644
--- a/arch/powerpc/include/asm/smp.h
+++ b/arch/powerpc/include/asm/smp.h
@@ -34,6 +34,20 @@ extern bool coregroup_enabled;
extern int cpu_to_chip_id(int cpu);
extern int *chip_id_lookup_table;

+#ifdef CONFIG_PPC_SPLPAR
+DECLARE_STATIC_KEY_FALSE(shared_processor);
+
+static inline bool is_shared_processor(void)
+{
+ return static_branch_unlikely(&shared_processor);
+}
+#else
+static inline bool is_shared_processor(void)
+{
+ return false;
+}
+#endif
+
DECLARE_PER_CPU(cpumask_var_t, thread_group_l1_cache_map);
DECLARE_PER_CPU(cpumask_var_t, thread_group_l2_cache_map);
DECLARE_PER_CPU(cpumask_var_t, thread_group_l3_cache_map);
--
2.31.1

2023-10-19 04:41:55

by Michael Ellerman

Subject: Re: [PATCH v2 3/6] powerpc/smp: Move shared_processor static key to smp.h

Srikar Dronamraju <[email protected]> writes:
> The ability to detect if the system is running in a shared processor
> mode is helpful in few more generic cases not just in
> paravirtualization.
> For example: At boot time, different scheduler/ topology flags may be
> set based on the processor mode. Hence move it to a more generic file.

I'd rather you just included paravirt.h in the few files where you need it.

cheers

> diff --git a/arch/powerpc/include/asm/paravirt.h b/arch/powerpc/include/asm/paravirt.h
> index 0372b0093f72..cf83e837a571 100644
> --- a/arch/powerpc/include/asm/paravirt.h
> +++ b/arch/powerpc/include/asm/paravirt.h
> @@ -15,13 +15,6 @@
> #include <asm/kvm_guest.h>
> #include <asm/cputhreads.h>
>
> -DECLARE_STATIC_KEY_FALSE(shared_processor);
> -
> -static inline bool is_shared_processor(void)
> -{
> - return static_branch_unlikely(&shared_processor);
> -}
> -
> #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
> extern struct static_key paravirt_steal_enabled;
> extern struct static_key paravirt_steal_rq_enabled;
> @@ -77,11 +70,6 @@ static inline bool is_vcpu_idle(int vcpu)
> return lppaca_of(vcpu).idle;
> }
> #else
> -static inline bool is_shared_processor(void)
> -{
> - return false;
> -}
> -
> static inline u32 yield_count_of(int cpu)
> {
> return 0;
> diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
> index aaaa576d0e15..08631b2a4528 100644
> --- a/arch/powerpc/include/asm/smp.h
> +++ b/arch/powerpc/include/asm/smp.h
> @@ -34,6 +34,20 @@ extern bool coregroup_enabled;
> extern int cpu_to_chip_id(int cpu);
> extern int *chip_id_lookup_table;
>
> +#ifdef CONFIG_PPC_SPLPAR
> +DECLARE_STATIC_KEY_FALSE(shared_processor);
> +
> +static inline bool is_shared_processor(void)
> +{
> + return static_branch_unlikely(&shared_processor);
> +}
> +#else
> +static inline bool is_shared_processor(void)
> +{
> + return false;
> +}
> +#endif
> +
> DECLARE_PER_CPU(cpumask_var_t, thread_group_l1_cache_map);
> DECLARE_PER_CPU(cpumask_var_t, thread_group_l2_cache_map);
> DECLARE_PER_CPU(cpumask_var_t, thread_group_l3_cache_map);
> --
> 2.31.1

2023-10-19 11:03:19

by Shrikanth Hegde

Subject: Re: [PATCH v2 3/6] powerpc/smp: Move shared_processor static key to smp.h

On 10/18/23 10:07 PM, Srikar Dronamraju wrote:
> The ability to detect if the system is running in a shared processor
> mode is helpful in few more generic cases not just in
> paravirtualization.
> For example: At boot time, different scheduler/ topology flags may be
> set based on the processor mode. Hence move it to a more generic file.
>
> Signed-off-by: Srikar Dronamraju <[email protected]>
> ---
> arch/powerpc/include/asm/paravirt.h | 12 ------------
> arch/powerpc/include/asm/smp.h | 14 ++++++++++++++
> 2 files changed, 14 insertions(+), 12 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/paravirt.h b/arch/powerpc/include/asm/paravirt.h
> index 0372b0093f72..cf83e837a571 100644
> --- a/arch/powerpc/include/asm/paravirt.h
> +++ b/arch/powerpc/include/asm/paravirt.h
> @@ -15,13 +15,6 @@
> #include <asm/kvm_guest.h>
> #include <asm/cputhreads.h>
>
> -DECLARE_STATIC_KEY_FALSE(shared_processor);
> -
> -static inline bool is_shared_processor(void)
> -{
> - return static_branch_unlikely(&shared_processor);
> -}
> -
> #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
> extern struct static_key paravirt_steal_enabled;
> extern struct static_key paravirt_steal_rq_enabled;
> @@ -77,11 +70,6 @@ static inline bool is_vcpu_idle(int vcpu)
> return lppaca_of(vcpu).idle;
> }

Hi Srikar,

This patch fails to apply on tip/master as it depends on
https://lore.kernel.org/all/[email protected]/ to be applied first.

> #else
> -static inline bool is_shared_processor(void)
> -{
> - return false;
> -}
> -
> static inline u32 yield_count_of(int cpu)
> {
> return 0;
> diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
> index aaaa576d0e15..08631b2a4528 100644
> --- a/arch/powerpc/include/asm/smp.h
> +++ b/arch/powerpc/include/asm/smp.h
> @@ -34,6 +34,20 @@ extern bool coregroup_enabled;
> extern int cpu_to_chip_id(int cpu);
> extern int *chip_id_lookup_table;
>
> +#ifdef CONFIG_PPC_SPLPAR
> +DECLARE_STATIC_KEY_FALSE(shared_processor);
> +
> +static inline bool is_shared_processor(void)
> +{
> + return static_branch_unlikely(&shared_processor);
> +}
> +#else
> +static inline bool is_shared_processor(void)
> +{
> + return false;
> +}
> +#endif
> +
> DECLARE_PER_CPU(cpumask_var_t, thread_group_l1_cache_map);
> DECLARE_PER_CPU(cpumask_var_t, thread_group_l2_cache_map);
> DECLARE_PER_CPU(cpumask_var_t, thread_group_l3_cache_map);

2023-10-19 13:10:50

by Srikar Dronamraju

Subject: Re: [PATCH v2 3/6] powerpc/smp: Move shared_processor static key to smp.h

* Michael Ellerman <[email protected]> [2023-10-19 15:41:40]:

> Srikar Dronamraju <[email protected]> writes:
> > The ability to detect if the system is running in a shared processor
> > mode is helpful in few more generic cases not just in
> > paravirtualization.
> > For example: At boot time, different scheduler/ topology flags may be
> > set based on the processor mode. Hence move it to a more generic file.
>
> I'd rather you just included paravirt.h in the few files where you need it.


I thought, detecting if a Processor was shared or not was more a
smp/processor related than a paravirt related.

Will drop as suggested.

>
> cheers
>
> > diff --git a/arch/powerpc/include/asm/paravirt.h b/arch/powerpc/include/asm/paravirt.h
> > index 0372b0093f72..cf83e837a571 100644
> > --- a/arch/powerpc/include/asm/paravirt.h
> > +++ b/arch/powerpc/include/asm/paravirt.h
> > @@ -15,13 +15,6 @@
> > #include <asm/kvm_guest.h>
> > #include <asm/cputhreads.h>
> >
> > -DECLARE_STATIC_KEY_FALSE(shared_processor);
> > -
> > -static inline bool is_shared_processor(void)
> > -{
> > - return static_branch_unlikely(&shared_processor);
> > -}
> > -
> > #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
> > extern struct static_key paravirt_steal_enabled;
> > extern struct static_key paravirt_steal_rq_enabled;
> > @@ -77,11 +70,6 @@ static inline bool is_vcpu_idle(int vcpu)
> > return lppaca_of(vcpu).idle;
> > }
> > #else
> > -static inline bool is_shared_processor(void)
> > -{
> > - return false;
> > -}
> > -
> > static inline u32 yield_count_of(int cpu)
> > {
> > return 0;
> > diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
> > index aaaa576d0e15..08631b2a4528 100644
> > --- a/arch/powerpc/include/asm/smp.h
> > +++ b/arch/powerpc/include/asm/smp.h
> > @@ -34,6 +34,20 @@ extern bool coregroup_enabled;
> > extern int cpu_to_chip_id(int cpu);
> > extern int *chip_id_lookup_table;
> >
> > +#ifdef CONFIG_PPC_SPLPAR
> > +DECLARE_STATIC_KEY_FALSE(shared_processor);
> > +
> > +static inline bool is_shared_processor(void)
> > +{
> > + return static_branch_unlikely(&shared_processor);
> > +}
> > +#else
> > +static inline bool is_shared_processor(void)
> > +{
> > + return false;
> > +}
> > +#endif
> > +
> > DECLARE_PER_CPU(cpumask_var_t, thread_group_l1_cache_map);
> > DECLARE_PER_CPU(cpumask_var_t, thread_group_l2_cache_map);
> > DECLARE_PER_CPU(cpumask_var_t, thread_group_l3_cache_map);
> > --
> > 2.31.1

--
Thanks and Regards
Srikar Dronamraju

2023-10-20 10:46:21

by Michael Ellerman

Subject: Re: [PATCH v2 3/6] powerpc/smp: Move shared_processor static key to smp.h

Srikar Dronamraju <[email protected]> writes:
> * Michael Ellerman <[email protected]> [2023-10-19 15:41:40]:
>
>> Srikar Dronamraju <[email protected]> writes:
>> > The ability to detect if the system is running in a shared processor
>> > mode is helpful in few more generic cases not just in
>> > paravirtualization.
>> > For example: At boot time, different scheduler/ topology flags may be
>> > set based on the processor mode. Hence move it to a more generic file.
>>
>> I'd rather you just included paravirt.h in the few files where you need it.
>
> I thought, detecting if a Processor was shared or not was more a
> smp/processor related than a paravirt related.

It's both really :)

It's definitely paravirt related though, because if we weren't
*para*virt then we wouldn't know there was a hypervisor at all :)

But having smaller more focused headers is preferable in general just
for mechanical reasons.

cheers