linux-kernel - Re: [PATCH v7 4/8] x86/resctrl: Add comments on RFTYPE flags hierarchy

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Date:   Thu, 17 Aug 2023 12:07:44 -0500
From:   "Moger, Babu" <babu.moger@....com>
To:     Reinette Chatre <reinette.chatre@...el.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 v7 4/8] x86/resctrl: Add comments on RFTYPE flags
 hierarchy

Hi Reinette,

On 8/17/23 10:37, Reinette Chatre wrote:
> Hi Babu,
> 
> On 8/17/2023 7:20 AM, Moger, Babu wrote:
> 
>> Yea. We can go with it. How about adding a little note about directories?
>> That might be easy to compare directory structure on a systems with these
>> flags. Something like this.
> 
> 
> Thank you for improving it.
> 
>> + *
>> + * 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 does not use flags for directories. Directories are
>> + *           created based on the resource type. Added directories below
>> + *           for better understanding.
> 
> This is very helpful. How about a more specific "resctrl uses flags for
> files, not for directories. Directories are ..."
> 
Sure.

>> + *
>> + *     info directory structure
>> + *     ------------------------------------------------------------------
>> + *     --> RFTYPE_INFO
>> + *         directory: info
> 
> directory -> Directory ? (for all directory/directories instances)

Sure.

> 
>> + *             --> RFTYPE_TOP (Files in top level of info directory)
>> + *                 Files: last_cmd_status
> 
> (nitpick) Considering the directory vs directories, maybe this can be "File:"
> until more files are added.

Yes.

> 
>> + *
>> + *             --> RFTYPE_MON (Files for all monitoring resources)
>> + *                 directory: L3_MON
> 
> Should this not be below RFTYPE_RES_CACHE? 

This is kind of odd. I know why you are saying it. Wouldn't it confuse the
user? Then, it feels like mon_features and num_rmids don't belong L3_MON.


>> + *                     Files: mon_features, num_rmids
> 
> 
> 
>> + *
>> + *                     --> RFTYPE_RES_CACHE (Files for cache monitoring
>> resources)
>> + *                         Files: max_threshold_occupancy,
>> + *                                mbm_total_bytes_config,
>> + *                                mbm_local_bytes_config
>> + *
>> + *             --> RFTYPE_CTRL (Files for all control resources)
>> + *                 Files: num_closids
> 
> Maybe this should just be "File:" for now?

Sure.

> 
>> + *
>> + *                     --> RFTYPE_RES_CACHE (Files for cache control
>> resources)
>> + *                         directories: L2,L3
> 
> Please add a space after the comma.

Sure

> 
>> + *                               Files: bit_usage, cbm_mask, min_cbm_bits,
>> + *                                      shareable_bits
> 
> The extra indent is not clear to me. Did you do it to represent
> a hierarchy or just to line up the ":"?

This is to line up with :. I can fix it.

Just wondering how do you notice these tabs? My linux diff does not show
any difference. Are you using any utilities to see these tabs?

> 
> 
>> + *
>> + *                     --> RFTYPE_RES_MB (Files for memory control resources)
>> + *                         directories: MB,SMBA
> 
> Space after comma here also.

Sure.

> 
>> + *                               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
>>
>>
> 
> Thank you very much. 
> 
> Reinette

-- 
Thanks
Babu Moger