linux-kernel - Re: [PATCH v9 9/9] x86/resctrl: Display RMID of resource group

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Date:   Tue, 12 Sep 2023 14:45:23 -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 v9 9/9] x86/resctrl: Display RMID of resource group

Hi Reinette,

On 9/12/23 12:57, Reinette Chatre wrote:
> Hi Babu,
> 
> On 9/12/2023 10:39 AM, Moger, Babu wrote:
>> On 9/11/23 18:08, Reinette Chatre wrote:
>>> Hi Babu,
>>>
>>> On 9/7/2023 4:51 PM, Babu Moger wrote:
>>>> In x86, hardware uses RMID to identify a a monitoring group. When a
>>>> user creates a monitor group these details are not visible. These details
>>>> can help resctrl debugging.
>>>>
>>>> Add RMID(mon_hw_id) to the monitor groups display in resctrl interface.
>>>> Users can see these details when resctrl is mounted with "-o debug" option.
>>>>
>>>> Other architectures do not use "RMID". Use the name mon_hw_id to refer
>>>> to "RMID" in an effort to keep the naming generic.
>>>>
>>>> Add the flag RFTYPE_MON_BASE, which contains the files required only
>>>> for the MON group.
>>>
>>> As I mentioned in [1] I believe adding support for files with RFTYPE_MON flag
>>> to resctrl needs to be in a separate patch. With the core support added a file
>>> with this flag can be introduced separately. 
>>
>> Yes. We discussed it. Thought it may not fit as a separate patch on its
>> own. So, i combined it.
>>
>> Now, I split patch 9 into two. Let me know if it looks ok.
>>
>> ==========================================================================
>>
>> Author: Babu Moger <babu.moger@....com>
>> Date:   Thu Sep 7 18:51:28 2023 -0500
>>
>>     x86/resctrl: Add RFTYPE_MON_BASE for MON groups
>>
>>     Add the flag RFTYPE_MON_BASE, which contains the files required only
>>     for the MON group. Files with these flags are only visible when
>>     monitoring is enabled.
>>
>>     Signed-off-by: Babu Moger <babu.moger@....com>
>>
>> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h
>> b/arch/x86/kernel/cpu/resctrl/internal.h
>> index ccdbed615d41..72988e5c52a7 100644
>> --- a/arch/x86/kernel/cpu/resctrl/internal.h
>> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
>> @@ -296,6 +296,8 @@ struct rdtgroup {
>>   *     --> RFTYPE_BASE (Files common for both MON and CTRL groups)
>>   *         Files: cpus, cpus_list, tasks
>>   *
>> + *             --> RFTYPE_MON (Files only for MON group)
>> + *
>>   *             --> RFTYPE_CTRL (Files only for CTRL group)
>>   *                 Files: mode, schemata, size
>>   *
> 
> I think it would be ok to add above hunk as part of the patch
> that adds mon_hw_id, similar to what you did in patch 8.

Ok. Sure.
> 
>> @@ -315,6 +317,7 @@ struct rdtgroup {
>>  #define RFTYPE_MON_INFO                        (RFTYPE_INFO | RFTYPE_MON)
>>  #define RFTYPE_TOP_INFO                        (RFTYPE_INFO | RFTYPE_TOP)
>>  #define RFTYPE_CTRL_BASE               (RFTYPE_BASE | RFTYPE_CTRL)
>> +#define RFTYPE_MON_BASE                        (RFTYPE_BASE | RFTYPE_MON)
>>
> 
> This hunk may be appropriate for patch 3.

Sure.

> 
>>  /* List of all resource groups */
>>  extern struct list_head rdt_all_groups;
>>
> 
> This is not how I expected it to look. There is currently an issue
> in resctrl where files with RFTYPE_MON are not created for CTRL_MON
> groups. This has not actually been a problem because there are
> no files with the RFTYPE_MON flag. This series introduces the first
> file with RFTYPE_MON flag and thus this resctrl issue needs to be fixed
> before this new file can be supported.
Yes.
> 
> Considering this I expected to see the changes in rdt_get_tree()
> and mkdir_rdt_prepare() done as a separate patch. This will add
> support for RFTYPE_MON files to resctrl. After this change
> a separate patch can add the file that has this flag.
> 
Sure. Got it.
Thanks
Babu Moger