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

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Date:   Thu, 17 Aug 2023 08:37:45 -0700
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     <babu.moger@....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 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 ..."

> + *
> + *     info directory structure
> + *     ------------------------------------------------------------------
> + *     --> RFTYPE_INFO
> + *         directory: info

directory -> Directory ? (for all directory/directories instances)

> + *             --> 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.

> + *
> + *             --> RFTYPE_MON (Files for all monitoring resources)
> + *                 directory: L3_MON

Should this not be below RFTYPE_RES_CACHE? 

> + *                     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?

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

Please add a space after the comma.

> + *                               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 ":"?


> + *
> + *                     --> RFTYPE_RES_MB (Files for memory control resources)
> + *                         directories: MB,SMBA

Space after comma here also.

> + *                               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