linux-kernel - Re: [PATCH v8 06/13] arch/resctrl: Initialize the resource functions that are different

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Message-ID: <20181120095918.GD2527@zn.tnic>
Date:   Tue, 20 Nov 2018 10:59:18 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "Moger, Babu" <Babu.Moger@....com>
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Subject: Re: [PATCH v8 06/13] arch/resctrl: Initialize the resource functions
 that are different

On Fri, Nov 16, 2018 at 08:54:32PM +0000, Moger, Babu wrote:
> Initialize the resource functions that are different between the
> vendors. Some features are initialized differently between the vendors.
> Add _intel suffix to Intel specific functions.
> 
> For example, MBA feature varies significantly between Intel and AMD.
> Separate the initialization of these resource functions. That way we
> can easily add AMD's functions later.
> 
> Signed-off-by: Babu Moger <babu.moger@....com>
> ---
>  arch/x86/kernel/cpu/resctrl.c             | 34 +++++++++++++++++++----
>  arch/x86/kernel/cpu/resctrl.h             |  8 ++++--
>  arch/x86/kernel/cpu/resctrl_ctrlmondata.c |  4 +--
>  3 files changed, 37 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl.c b/arch/x86/kernel/cpu/resctrl.c
> index 18c8222f326c..eeb7e0e4883e 100644
> --- a/arch/x86/kernel/cpu/resctrl.c
> +++ b/arch/x86/kernel/cpu/resctrl.c
> @@ -57,7 +57,8 @@ int max_name_width, max_data_width;
>  bool rdt_alloc_capable;
>  
>  static void
> -mba_wrmsr(struct rdt_domain *d, struct msr_param *m, struct rdt_resource *r);
> +mba_wrmsr_intel(struct rdt_domain *d, struct msr_param *m,
> +		struct rdt_resource *r);
>  static void
>  cat_wrmsr(struct rdt_domain *d, struct msr_param *m, struct rdt_resource *r);
>  
> @@ -171,10 +172,7 @@ struct rdt_resource rdt_resources_all[] = {
>  		.rid			= RDT_RESOURCE_MBA,
>  		.name			= "MB",
>  		.domains		= domain_init(RDT_RESOURCE_MBA),
> -		.msr_base		= IA32_MBA_THRTL_BASE,
> -		.msr_update		= mba_wrmsr,
>  		.cache_level		= 3,
> -		.parse_ctrlval		= parse_bw,
>  		.format_str		= "%d=%*u",
>  		.fflags			= RFTYPE_RES_MB,
>  	},
> @@ -356,7 +354,8 @@ u32 delay_bw_map(unsigned long bw, struct rdt_resource *r)
>  }
>  
>  static void
> -mba_wrmsr(struct rdt_domain *d, struct msr_param *m, struct rdt_resource *r)
> +mba_wrmsr_intel(struct rdt_domain *d, struct msr_param *m,
> +		struct rdt_resource *r)
>  {
>  	unsigned int i;
>  
> @@ -873,6 +872,25 @@ static __init bool get_rdt_resources(void)
>  	return (rdt_mon_capable || rdt_alloc_capable);
>  }
>  
> +static __init void rdt_init_res_defs_intel(void)
> +{
> +	struct rdt_resource *r;
> +
> +	for_each_rdt_resource(r) {
> +		if (r->rid == RDT_RESOURCE_MBA) {
> +			r->msr_base = IA32_MBA_THRTL_BASE;
> +			r->msr_update = mba_wrmsr_intel;
> +			r->parse_ctrlval = parse_bw_intel;
> +		}
> +	}
> +}
> +
> +static __init void rdt_init_res_defs(void)
> +{
> +	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
> +		rdt_init_res_defs_intel();
> +}

So I'm wondering: instead of having mba_wrmsr_intel() and
mba_wrmsr_amd() and adding those per-vendor initialization functions,
why don't you push down the vendor differentiation into mba_wrmsr()?

Then in that function you do

	if (vendor == X86_VENDOR_INTEL)
		__mba_wrmsr_intel();
	else if (vendor == X86_VENDOR_AMD)
		__mba_wrmsr_amd();

and so on and then you don't have to do any of that initialization dance
here and the struct rdt_resource assignment for the MBA will remain
nicely similar to the other ones...

Hmmm?

-- 
Regards/Gruss,
    Boris.

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