linux-kernel - Re: [PATCH v9 02/13] x86/resctrl: Add a new resource type RDT_RESOURCE

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Date:   Thu, 15 Dec 2022 09:10:31 -0800
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     Babu Moger <babu.moger@....com>, <corbet@....net>,
        <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>
CC:     <fenghua.yu@...el.com>, <dave.hansen@...ux.intel.com>,
        <x86@...nel.org>, <hpa@...or.com>, <paulmck@...nel.org>,
        <akpm@...ux-foundation.org>, <quic_neeraju@...cinc.com>,
        <rdunlap@...radead.org>, <damien.lemoal@...nsource.wdc.com>,
        <songmuchun@...edance.com>, <peterz@...radead.org>,
        <jpoimboe@...nel.org>, <pbonzini@...hat.com>,
        <chang.seok.bae@...el.com>, <pawan.kumar.gupta@...ux.intel.com>,
        <jmattson@...gle.com>, <daniel.sneddon@...ux.intel.com>,
        <sandipan.das@....com>, <tony.luck@...el.com>,
        <james.morse@....com>, <linux-doc@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <bagasdotme@...il.com>,
        <eranian@...gle.com>, <christophe.leroy@...roup.eu>,
        <jarkko@...nel.org>, <adrian.hunter@...el.com>,
        <quic_jiles@...cinc.com>, <peternewman@...gle.com>
Subject: Re: [PATCH v9 02/13] x86/resctrl: Add a new resource type
 RDT_RESOURCE_SMBA

Hi Babu,

On 12/1/2022 7:36 AM, Babu Moger wrote:
> Add a new resource type RDT_RESOURCE_SMBA to handle the QoS
> enforcement policies on the external slow memory.
> 

I think a snippet like below may help to set reviewer's mind at
ease about the consequences of values chosen:

"Mostly initialization of the essentials. Setting fflags to
RFTYPE_RES_MB configures the SMBA resource to have the same
resctrl files as the existing MBA resource. The SMBA resource 
has identical properties to the existing MBA resource. These
properties will be enumerated in an upcoming change and exposed
via resctrl because of this flag."

> Signed-off-by: Babu Moger <babu.moger@....com>
> ---
>  arch/x86/kernel/cpu/resctrl/core.c     |   12 ++++++++++++
>  arch/x86/kernel/cpu/resctrl/internal.h |    1 +
>  2 files changed, 13 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
> index c98e52ff5f20..f6af3ac1ef20 100644
> --- a/arch/x86/kernel/cpu/resctrl/core.c
> +++ b/arch/x86/kernel/cpu/resctrl/core.c
> @@ -100,6 +100,18 @@ struct rdt_hw_resource rdt_resources_all[] = {
>  			.fflags			= RFTYPE_RES_MB,
>  		},
>  	},
> +	[RDT_RESOURCE_SMBA] =
> +	{
> +		.r_resctrl = {
> +			.rid			= RDT_RESOURCE_SMBA,
> +			.name			= "SMBA",
> +			.cache_level		= 3,
> +			.domains		= domain_init(RDT_RESOURCE_SMBA),
> +			.parse_ctrlval		= parse_bw,
> +			.format_str		= "%d=%*u",
> +			.fflags			= RFTYPE_RES_MB,
> +		},
> +	},
>  };
>  
>  /*
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 5ebd28e6aa0c..fdbbf66312ec 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -409,6 +409,7 @@ enum resctrl_res_level {
>  	RDT_RESOURCE_L3,
>  	RDT_RESOURCE_L2,
>  	RDT_RESOURCE_MBA,
> +	RDT_RESOURCE_SMBA,
>  
>  	/* Must be the last */
>  	RDT_NUM_RESOURCES,
> 
> 

Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>

Reinette