linux-kernel - Re: [PATCH v10 09/10] x86/resctrl: Add support for the files for MON groups only

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Message-ID: <8e6fec2d-2262-1f62-8c4e-cedfa8459434@intel.com>
Date:   Wed, 27 Sep 2023 15:02:42 -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>,
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        <eranian@...gle.com>, <christophe.leroy@...roup.eu>,
        <jarkko@...nel.org>, <adrian.hunter@...el.com>,
        <quic_jiles@...cinc.com>, <peternewman@...gle.com>
Subject: Re: [PATCH v10 09/10] x86/resctrl: Add support for the files for MON
 groups only

Hi Babu,

On 9/27/2023 2:34 PM, Moger, Babu wrote:
> Hi Reinette,
> 
> On 9/27/2023 1:34 PM, Reinette Chatre wrote:
>> Hi Babu,
>>
>> On 9/15/2023 3:42 PM, Babu Moger wrote:
>>> There are 3 types resctrl root files.
>> Considering patch #4, should this be "base"?
> Sure.
>>
>>> 1. RFTYPE_BASE : Files common for both MON and CTRL groups
>>> 2. RFTYPE_BASE | RFTYPE_CTRL : Files only for CTRL groups
>> If (1) is accurate then I cannot see how (2) can be accurate.
> 
> How about ?
> 
> 2. RFTYPE_BASE | RFTYPE_CTRL : Files for the CTRL groups

Yes, this is accurate. Even so, this snippet does not seem
necessary considering the changelog rewrite below.

> 
>>
>>> 3. RFTYPE_BASE | RFTYPE_MON : Files only for MON groups
>> Same here.
> 
> How bout?
> 
> 3. RFTYPE_BASE | RFTYPE_MON : Files for the MON groups

Same comment.

> 
>>
>>> Files only for the MON groups are not supported now. Add the
>>> support to create these files.
>> This is not accurate. Files "only for the MON groups" are
>> actually the only monitor files that *are* supported. The
>> problem being fixed here is that monitor files are
>> not supported for CTRL_MON groups.
>>
>> I made an attempt at rewriting this commit message but I am
>> doing it quite quickly so please do improve it:
>>
>>     Files unique to monitoring groups have the
>>     RFTYPE_MON flag. When a new monitoring group is created
>>     the resctrl files with flags RFTYPE_BASE (files common
>>     to all resource groups) and RFTYPE_MON (files unique
>>     to monitoring groups) are created to support interacting with
>>     the new monitoring group.
>>
>>     A resource group can support both monitoring and control,
>>     also termed a CTRL_MON resource group. CTRL_MON groups should
>>     get both monitoring and control resctrl files but that
>>     is not the case. Only the RFTYPE_BASE and RFTYPE_CTRL files
>>     are created for    CTRL_MON groups. This is not a problem
>>     because there are no monitoring specific files with the
>>     RFTYPE_MON flag associated with resource groups.
>>
>>     A later patch introduces the first RFTYPE_MON file for
>>     resource groups so fix resctrl file creation for CTRL_MON
>>     groups to ensure that monitoring files,    those with the
>>     RFTYPE_MON flag, are also created.
> 
> Looks good with slight change(only last para. Rest looks good). Just removed the "fix".
> 
> A later patch introduces the first RFTYPE_MON file for
> resource groups. Add the changes to create the files for CTRL_MON
> groups to ensure that monitoring files,    those with the RFTYPE_MON flag,
> are also created.
> 

"Add the changes to" is not necessary. With this and removing the "fix" it
can be summarized to:
	A later patch introduces the first monitoring specific (RFTYPE_MON)
	file for resource groups. Ensure that files with the RFTYPE_MON
	flag are created for CTRL_MON groups.

What do you think?

Reinette