linux-kernel - Re: [PATCH v13 08/27] x86/resctrl: Introduce mbm_cntr_cfg to track assignable counters at domain

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Message-ID: <14ca1527-ee25-448d-949b-ed8df546c916@intel.com>
Date: Wed, 28 May 2025 10:34:04 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: "Moger, Babu" <bmoger@....com>, Babu Moger <babu.moger@....com>,
	<corbet@....net>, <tony.luck@...el.com>, <tglx@...utronix.de>,
	<mingo@...hat.com>, <bp@...en8.de>, <dave.hansen@...ux.intel.com>
CC: <james.morse@....com>, <dave.martin@....com>, <fenghuay@...dia.com>,
	<x86@...nel.org>, <hpa@...or.com>, <paulmck@...nel.org>,
	<akpm@...ux-foundation.org>, <thuth@...hat.com>, <rostedt@...dmis.org>,
	<ardb@...nel.org>, <gregkh@...uxfoundation.org>,
	<daniel.sneddon@...ux.intel.com>, <jpoimboe@...nel.org>,
	<alexandre.chartre@...cle.com>, <pawan.kumar.gupta@...ux.intel.com>,
	<thomas.lendacky@....com>, <perry.yuan@....com>, <seanjc@...gle.com>,
	<kai.huang@...el.com>, <xiaoyao.li@...el.com>, <kan.liang@...ux.intel.com>,
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	<sohil.mehta@...el.com>, <andrew.cooper3@...rix.com>,
	<mario.limonciello@....com>, <linux-doc@...r.kernel.org>,
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	<maciej.wieczor-retman@...el.com>, <eranian@...gle.com>,
	<Xiaojian.Du@....com>, <gautham.shenoy@....com>
Subject: Re: [PATCH v13 08/27] x86/resctrl: Introduce mbm_cntr_cfg to track
 assignable counters at domain

Hi Babu,

On 5/28/25 9:56 AM, Moger, Babu wrote:
> On 5/22/2025 4:02 PM, Reinette Chatre wrote:
>> On 5/15/25 3:51 PM, Babu Moger wrote:

>>> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
>>> index bdb264875ef6..d77981d1fcb9 100644
>>> --- a/include/linux/resctrl.h
>>> +++ b/include/linux/resctrl.h
>>> @@ -156,6 +156,20 @@ struct rdt_ctrl_domain {
>>>       u32                *mbps_val;
>>>   };
>>>   +/**
>>> + * struct mbm_cntr_cfg - Assignable counter configuration
>>> + * @evtid:        MBM event to which the counter is assigned. Only valid
>>> + *            if @rdtgroup is not NULL.
>>> + * @evt_cfg:        Event configuration value.
>>
>> @evt_cfg is not introduced in changelog nor defined here. Please add a snippet here
>> on what @evt_cfg's values represent. This is important since this is exposed
>> as resctrl fs API to architectures so all architectures need to use same values when
>> interacting with resctrl.
> 
> Sure.
> 
> @evt_cfg: A value that represents memory transactions (e.g., reads, writes, etc.).

This still does not explain how an @evt_cfg value should be interpreted. For example, it
could be something like below (please feel free to improve).

@evt_cfg: Event configuration created using the READS_TO_LOCAL_MEM, READS_TO_REMOTE_MEM, etc. bits
	  that represent the memory transactions being counted.

Reinette