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

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Message-ID: <031ef099-a7d2-37ce-eb97-c4f7d76a12c4@intel.com>
Date:   Wed, 27 Sep 2023 11:34:45 -0700
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     Babu Moger <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 v10 09/10] x86/resctrl: Add support for the files for MON
 groups only

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"?

> 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.

> 3. RFTYPE_BASE | RFTYPE_MON : Files only for MON groups

Same here.

> 
> 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.
 
> Signed-off-by: Babu Moger <babu.moger@....com>
> ---

I only have feedback about the changelog. The patch looks good to me.

Reinette