[PATCH 1/4] score: Add _CPU_Get_current_per_CPU_control()

[Gedare Bloom]

What is the need/use for this optimization?

On Tue, Apr 22, 2014 at 4:46 AM, Sebastian Huber
<sebastian.huber at embedded-brains.de> wrote:
> Add optional method _CPU_Get_current_per_CPU_control() to obtain the
> per-CPU control of the current processor.
>
> This is optional.  Not every CPU port needs this.  It is only an
> optional optimization variant.  In case this macro is undefined, the
> default implementation using the current processor index will be used.
> ---
>  cpukit/score/cpu/no_cpu/rtems/score/cpu.h |   18 ++++++++++++++++++
>  cpukit/score/include/rtems/score/percpu.h |   10 +++++++---
>  2 files changed, 25 insertions(+), 3 deletions(-)
>
> diff --git a/cpukit/score/cpu/no_cpu/rtems/score/cpu.h b/cpukit/score/cpu/no_cpu/rtems/score/cpu.h
> index 5241b5b..959fb58 100644
> --- a/cpukit/score/cpu/no_cpu/rtems/score/cpu.h
> +++ b/cpukit/score/cpu/no_cpu/rtems/score/cpu.h
> @@ -1462,6 +1462,24 @@ CPU_Counter_ticks _CPU_Counter_difference(
>    CPU_Counter_ticks first
>  );
>
> +/**
> + * @brief Special register pointing to the per-CPU control of the current
> + * processor.
> + *
> + * This is optional.  Not every CPU port needs this.  It is only an optional
> + * optimization variant.
> + */
> +register struct Per_CPU_Control *_CPU_Per_CPU_current asm( "rX" );
> +
> +/**
> + * @brief Optional method to obtain the per-CPU control of the current processor.
> + *
> + * This is optional.  Not every CPU port needs this.  It is only an optional
> + * optimization variant.  In case this macro is undefined, the default
> + * implementation using the current processor index will be used.
> + */
> +#define _CPU_Get_current_per_CPU_control() ( _CPU_Per_CPU_current )
> +
>  #ifdef RTEMS_SMP
>    /**
>     * @brief Performs CPU specific SMP initialization in the context of the boot
> diff --git a/cpukit/score/include/rtems/score/percpu.h b/cpukit/score/include/rtems/score/percpu.h
> index afc3803..a1b0a38 100644
> --- a/cpukit/score/include/rtems/score/percpu.h
> +++ b/cpukit/score/include/rtems/score/percpu.h
> @@ -235,7 +235,7 @@ typedef struct {
>   *
>   *  This structure is used to hold per core state information.
>   */
> -typedef struct {
> +typedef struct Per_CPU_Control {
>    /**
>     * @brief CPU port specific control.
>     */
> @@ -437,8 +437,12 @@ extern Per_CPU_Control_envelope _Per_CPU_Information[] CPU_STRUCTURE_ALIGNMENT;
>   * we can use _Per_CPU_Get_snapshot()).  All other places must use
>   * _Per_CPU_Get() so that we can add checks for RTEMS_DEBUG.
>   */
> -#define _Per_CPU_Get_snapshot() \
> -  ( &_Per_CPU_Information[ _SMP_Get_current_processor() ].per_cpu )
> +#if defined( _CPU_Get_current_per_CPU_control )
> +  #define _Per_CPU_Get_snapshot() _CPU_Get_current_per_CPU_control()
> +#else
> +  #define _Per_CPU_Get_snapshot() \
> +    ( &_Per_CPU_Information[ _SMP_Get_current_processor() ].per_cpu )
> +#endif
>
>  #if defined( RTEMS_SMP )
>  static inline Per_CPU_Control *_Per_CPU_Get( void )
> --
> 1.7.7
>
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