linux-kernel - Re: [PATCH v2 3/6] powerpc/smp: Move shared

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Message-ID: <b57962d9-93dc-4545-8d4f-37f5e071fc0b@linux.vnet.ibm.com>
Date:   Thu, 19 Oct 2023 16:00:50 +0530
From:   Shrikanth Hegde <sshegde@...ux.vnet.ibm.com>
To:     Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:     Valentin Schneider <vschneid@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-kernel@...r.kernel.org, x86@...nel.org,
        Ajay Kaher <akaher@...are.com>,
        virtualization@...ts.linux-foundation.org,
        VMware PV-Drivers Reviewers <pv-drivers@...are.com>,
        Rohan McLure <rmclure@...ux.ibm.com>,
        Nicholas Piggin <npiggin@...il.com>,
        Alexey Makhalov <amakhalov@...are.com>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>
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 <srikar@...ux.vnet.ibm.com>
> ---
>  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/20231019091452.95260-1-srikar@linux.vnet.ibm.com/ 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);