Re: [PATCH v12 12/25] arm,x86,fs/resctrl: Allocate maximum needed rmid_ptrs[]

[Babu Moger]

Hi Tony,


On 9/16/26 18:13, Tony Luck wrote:
> File system code allocates the rmid_ptrs[] array once during
> initialization. The number of entries needed in this array is currently
> constant. When changes are made to allow Application Energy Telemetry
> (AET) to run with the pmt_telemetry driver as a module, then number of
> entries needed may change from one mount to the next.
>
> Allocate rmid_ptrs[] with enough entries for any future mount.
>
> Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
> ---
> v12:
> 	New patch. Split out from old patch 12.
> 	New global pqr_assoc_num_rmid to avoid repeat CPUID calls.
> ---
>   include/linux/resctrl.h            |  1 +
>   arch/x86/kernel/cpu/resctrl/core.c | 27 +++++++++++++++++++++++++++
>   drivers/resctrl/mpam_resctrl.c     |  9 +++++++++
>   fs/resctrl/monitor.c               |  2 +-
>   4 files changed, 38 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> index fbf737e884db..5535bde7b925 100644
> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
> @@ -447,6 +447,7 @@ static inline u32 resctrl_get_default_ctrl(struct rdt_resource *r)
>   /* The number of closid supported by this resource regardless of CDP */
>   u32 resctrl_arch_get_num_closid(struct rdt_resource *r);
>   u32 resctrl_arch_system_num_rmid_idx(void);
> +u32 resctrl_arch_system_max_rmid_idx(void);
>   int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid);
>   
>   /**
> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
> index 2e3b9c16cbda..a9109f2bc43e 100644
> --- a/arch/x86/kernel/cpu/resctrl/core.c
> +++ b/arch/x86/kernel/cpu/resctrl/core.c
> @@ -45,6 +45,9 @@ static DEFINE_MUTEX(domain_list_lock);
>    */
>   DEFINE_PER_CPU(struct resctrl_pqr_state, pqr_state);
>   
> +/* Number of RMIDS values that can be written to IA32_PQR_ASSOC.RMID */
> +static u32 pqr_assoc_num_rmid;
> +
>   static void mba_wrmsr_intel(struct msr_param *m);
>   static void cat_wrmsr(struct msr_param *m);
>   static void mba_wrmsr_amd(struct msr_param *m);
> @@ -124,6 +127,28 @@ u32 resctrl_arch_system_num_rmid_idx(void)
>   	return num_rmids == U32_MAX ? 0 : num_rmids;
>   }
>   
> +/**
> + * resctrl_arch_system_max_rmid_idx - Largest possible number of RMIDs
> + *
> + * Return: Maximum possible number of RMIDs used for boot time allocations.
> + */
> +u32 resctrl_arch_system_max_rmid_idx(void)
> +{
> +	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
> +	u32 num_rmid = pqr_assoc_num_rmid;

Why not  use "cpuid_ebx(0xf) + 1" instead of global variable?

Thanks
Babu