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Subject: [PATCH v12 04/10] x86/resctrl: Add comments on RFTYPE flags hierarchy
Date:   Tue, 10 Oct 2023 18:33:29 -0500
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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@amd.com>
Tested-by: Peter Newman <peternewman@google.com>
Reviewed-by: Peter Newman <peternewman@google.com>
Tested-by: Tan Shaopeng <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Tan Shaopeng <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
v12: Moved the comments from arch/x86/kernel/cpu/resctrl/internal.h
     to Documentation/arch/x86/resctrl.rst. (Boris)
---
 Documentation/arch/x86/resctrl.rst | 60 ++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)

diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index 8154e9975d1e..520a7753d829 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -362,6 +362,66 @@ When monitoring is enabled all MON groups will also contain:
 	the sum for all tasks in the CTRL_MON group and all tasks in
 	MON groups. Please see example section for more details on usage.
 
+RESCTRL filesystem implementation notes
+=======================================
+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. The RFTYPE flags
+	      are defined in arch/x86/kernel/cpu/resctrl/internal.h.
+
+	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, L2CODE, L2DATA, L3CODE, L3DATA
+	           File: num_closids
+
+		--> RFTYPE_RES_CACHE (Files for cache control resources)
+		    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 for CTRL group)
+		    Files: mode, schemata, size
+
 Resource allocation rules
 -------------------------
 
-- 
2.34.1