linux-kernel - Re: [PATCH v8 4/8] x86/resctrl: Add comments on RFTYPE flags hierarchy

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Message-ID: <6a5ed053-5d4d-f098-d37f-17eec3554536@intel.com>
Date:   Fri, 1 Sep 2023 15:31:02 -0700
From:   Fenghua Yu <fenghua.yu@...el.com>
To:     Babu Moger <babu.moger@....com>, <corbet@....net>,
        <reinette.chatre@...el.com>, <tglx@...utronix.de>,
        <mingo@...hat.com>, <bp@...en8.de>
CC:     <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 v8 4/8] x86/resctrl: Add comments on RFTYPE flags
 hierarchy

Hi, Babu,

On 8/21/23 16:30, Babu Moger wrote:
> resctrl uses RFTYPE flags for creating resctrl directory structure.
> 
> Definitions and directory structures are not documented. Add
> comments to improve the readability and help future additions.
> 
> Signed-off-by: Babu Moger <babu.moger@....com>
> ---
>   arch/x86/kernel/cpu/resctrl/internal.h | 58 ++++++++++++++++++++++++++
>   1 file changed, 58 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 2051179a3b91..b09e7abd1299 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -240,6 +240,64 @@ struct rdtgroup {
>   
>   /*
>    * Define the file type flags for base and info directories.
> + *
> + * RESCTRL filesystem has two main components
> + *	a. info
> + *	b. base
> + *
> + * /sys/fs/resctrl/
> + *	|
> + *	--> info (Top level directory named "info". Contains files that
> + *	|	  provide details on control and monitoring resources.)
> + *	|
> + *	--> base (Root directory associated with default resource group
> + *		  as well as directories created by user for MON and CTRL
> + *		  groups. Contains files to interact with MON and CTRL
> + *		  groups.)
> + *
> + *	Note: resctrl uses flags for files, not for directories.
> + *	      Directories are created based on the resource type. Added
> + *	      directories below for better understanding.
> + *
> + *	info directory structure
> + *	------------------------------------------------------------------
> + *	--> RFTYPE_INFO
> + *	    directory: info
> + *		--> RFTYPE_TOP (Files in top level of info directory)
> + *		    File: last_cmd_status
> + *
> + *		--> RFTYPE_MON (Files for all monitoring resources)
> + *		    Directory: L3_MON
> + *		        Files: mon_features, num_rmids
> + *
> + *			--> RFTYPE_RES_CACHE (Files for cache monitoring resources)
> + *			    Directory: L3_MON
> + *			        Files: max_threshold_occupancy,
> + *			               mbm_total_bytes_config,
> + *			               mbm_local_bytes_config
> + *
> + *		--> RFTYPE_CTRL (Files for all control resources)
> + *		    Directories: L2, L3, MB, SMBA

L2 CDP and L3 CDP have different dirs. So need to add them here:

  + *		    Directories: L2, L3, MB, SMBA, L2CODE, L2DATA, L3CODE, L3DATA 
(L*CODE and L*DATA only available when CDP is enabled)

> + *		           File: num_closids
> + *
> + *			--> RFTYPE_RES_CACHE (Files for cache control resources)
> + *			    Directories: L2, L3

 > + *			    Directories: L2, L3

+ *			    Directories: L2, L3, L2CODE, L2DATA, L3CODE, L3DATA

> + *			          Files: bit_usage, cbm_mask, min_cbm_bits,
> + *			                 shareable_bits
> + *
> + *			--> RFTYPE_RES_MB (Files for memory control resources)
> + *			    Directories: MB, SMBA
> + *			          Files: bandwidth_gran, delay_linear,
> + *			                 min_bandwidth, thread_throttle_mode
> + *
> + *	base directory structure
> + *	------------------------------------------------------------------
> + *	--> RFTYPE_BASE (Files common for both MON and CTRL groups)
> + *	    Files: cpus, cpus_list, tasks
> + *
> + *		--> RFTYPE_CTRL (Files only for CTRL group)
> + *		    Files: mode, schemata, size
> + *
>    */
>   #define RFTYPE_INFO			BIT(0)
>   #define RFTYPE_BASE			BIT(1)

Thanks.

-Fenghua