Re: [PATCH v13 04/10] x86/resctrl: Add comments on RFTYPE flags hierarchy

[Moger, Babu]

Hi Reinette,

Boris pulled rest of the patches. Thank you very much for the feedback and
patience.

I can send this as a separate patch with all the FTYPE documentation
update. This need go later.


On 10/16/23 15:46, Reinette Chatre wrote:
> Hi Babu,
> 
> On 10/14/2023 4:06 PM, Moger, Babu wrote:
>> On 10/13/2023 4:39 PM, Moger, Babu wrote:
>>> On 10/13/2023 4:23 PM, Reinette Chatre wrote:
>>>> On 10/13/2023 1:25 PM, 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@xxxxxxx>
>>>>> ---
>>>>> v13: Fixed the format issues in the documentation. Needed few minor format
>>>>>       changes to address the syntax issues.(Reinette)
>>>>>       Removed "Reviewed-by and Tested-by" flags as the patch has changed.
>>>>>
>>>>> v12: Moved the comments from arch/x86/kernel/cpu/resctrl/internal.h
>>>>>       to Documentation/arch/x86/resctrl.rst. (Boris)
>>>>> ---
>>>>>   Documentation/arch/x86/resctrl.rst | 64 ++++++++++++++++++++++++++++++
>>>>>   1 file changed, 64 insertions(+)
>>>>>
>>>>> diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
>>>>> index 178ab1d8f747..1163da74f734 100644
>>>>> --- a/Documentation/arch/x86/resctrl.rst
>>>>> +++ b/Documentation/arch/x86/resctrl.rst
>>>>> @@ -369,6 +369,70 @@ 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
>>>>> +
>>>> Could you please do a "make htmldocs" and then ensure that the output looks sane?
>>>> The resulting output does not look right to me. For example, the above turns into
>>>> a single line that looks like:
>>>>
>>>> /sys/fs/resctrl/ | -> info | | (Top level directory named "info". Contains files that | provide details on control and monitoring resources") | -> base
>>>>
>>>>
>>>> The spacing also looks off when viewing this in html.
>>>
>> I have fixed the all the format issues. Please let me know if it
>> looks ok. I will send the final version after that.
>>
>> Attached the patch and also added the diff inline.
> 
> This still does not look as though you consider how the document 
> looks after the changes.
> 
> Consider the organization. Before your changes (assume numbering starts
> at 1):
> 
> 1. User Interface for Resource Control feature
> 1.1 Info directory
> 1.2 Resource alloc and monitor groups
> 1.2.1 Resource allocation rules
> 1.2.2 Resource monitoring rules
> 1.3 Notes on cache occupancy monitoring and control
> ...
> 
> After your changes:
> 
> 1. User Interface for Resource Control feature
> 1.1 Info directory
> 1.2 Resource alloc and monitor groups
> 1.2.1 Resource allocation rules
> 1.2.2 Resource monitoring rules
> 1.2.3 RESCTRL filesystem implementation notes
> 1.3 Notes on cache occupancy monitoring and control
> ...
> 
> Note how the "RESCTRL filesystem implementation notes" is inserted
> as a subsection of resource and monitoring groups. Since the text
> describes all files in resctrl (not just resource groups) I expect
> that it would not be buried as a subsection of resource groups.

we can make a separate sub chapter for this. Something like this.

1. User Interface for Resource Control feature
1.1 Info directory
1.2 Resource alloc and monitor groups
1.2.1 Resource allocation rules
1.2.2 Resource monitoring rules
1.3 RESCTRL filesystem implementation notes
1.3.1 info directory structure
1.3.2 base directory structure
1.3 Notes on cache occupancy monitoring and control

> 
> This addition also ignores existing customs. Nowhere in the
> entire document will you find "RESCTRL" (well, except for the
> config option).

Sure. We can change this to "resctrl"

>  
>> Thanks
>>
>> diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
>> index 178ab1d8f747..e990272e9a4f 100644
>> --- a/Documentation/arch/x86/resctrl.rst
>> +++ b/Documentation/arch/x86/resctrl.rst
>> @@ -396,6 +396,67 @@ Resource monitoring rules
>>  3) Otherwise RDT events for the task will be reported in the root level
>>     "mon_data" group.
>>
>> +RESCTRL filesystem implementation notes
>> +---------------------------------------
>> +RESCTRL filesystem has two main components.
> 
> This documentation was extracted as-is from the header file where it
> was next to the flags being documented. With this move all that context
> is lost so it may be helpful to summarize what is documented here.

I can move the notes here with some modifications.

> 
>> +
>> +a. info
>> +b. base
>> +
>> +::
> 
> If I understand correctly, instead of adjusting to the target format you
> hardcode all the text as pre-formatted? That may be ok. I cannot speak to
> whether this matches expectations of the proposal to move the documentation
> here.

I am not sure either.

> 
>> +
>> +       /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 the directories
>> +                     below for better understanding. The RFTYPE flags are defined
>> +                     in arch/x86/kernel/cpu/resctrl/internal.h.
>> +
>> +"info directory structure"::
>> +
> 
> This unexpected. In your previous response you noted that you did not know
> how to make it look like a header. I expected that you would read the manual
> to answer your own question but instead you just placed the title in quotes? I do
> not see how placing text in quotes create impression that it is a header.
> There is syntax to indicate section headers.

Actually, i have kind of understood all the formatting details. Still
learning though. Attached the patch.
-- 
Thanks
Babu MogerFrom 08e26841f82eccfef9cb3c5e27a2d7bc5ebeaf3a Mon Sep 17 00:00:00 2001
From: Babu Moger <babu.moger@xxxxxxx>
Date: Tue, 17 Oct 2023 11:34:33 -0500
Subject: [PATCH] x86/resctrl: Add comments on RFTYPE flags hierarchy

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@xxxxxxx>
---
 Documentation/arch/x86/resctrl.rst | 73 ++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)

diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index a6279df64a9d..c89a926934fe 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -407,6 +407,79 @@ Resource monitoring rules
 3) Otherwise RDT events for the task will be reported in the root level
    "mon_data" group.
 
+resctrl filesystem implementation notes
+=======================================
+
+This section lists the files and directories under resctrl filesystem to
+understand filesystem hierarchy. resctrl module uses RFTYPE flags defined
+in arch/x86/kernel/cpu/resctrl/internal.h to create files. Directories are
+created based on the resource type.
+
+resctrl filesystem has two main components.
+
+1) info
+2) 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)
+
+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_MON (Files for MON group)
+
+			--> RFTYPE_DEBUG (Files to help resctrl debugging)
+			    File: mon_hw_id
+
+		--> RFTYPE_CTRL (Files for CTRL group)
+		    Files: mode, schemata, size
+
+			-> RFTYPE_DEBUG (Files to help resctrl debugging)
+			   File: ctrl_hw_id
+
 
 Notes on cache occupancy monitoring and control
 ===============================================
-- 
2.34.1