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

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Message-ID: <TYAPR01MB6330B653E1F66310E57ED38F8B1CA@TYAPR01MB6330.jpnprd01.prod.outlook.com>
Date:   Wed, 23 Aug 2023 07:03:42 +0000
From:   "Shaopeng Tan (Fujitsu)" <tan.shaopeng@...itsu.com>
To:     'Babu Moger' <babu.moger@....com>,
        "'corbet@....net'" <corbet@....net>,
        "'reinette.chatre@...el.com'" <reinette.chatre@...el.com>,
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Subject: RE: [PATCH v8 4/8] x86/resctrl: Add comments on RFTYPE flags
 hierarchy

Hi Babu,


> 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
"directory" ->"Directory"

> + *		--> 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
> + *		           File: num_closids
> + *
> + *			--> RFTYPE_RES_CACHE (Files for cache control
> resources)
> + *			    Directories: L2, L3
> + *			          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
I think this is reinette's advice,
but "		--> RFTYPE_CTRL (Files only for CTRL group)" looks like a subdirectory.
Is this expected?

Best regards,
Shaopeng TAN