linux-kernel - Re: [PATCH v4 16/19] x86/resctrl: Enable ABMC by default on resctrl mount

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Date: Fri, 21 Jun 2024 11:29:29 -0500
From: "Moger, Babu" <bmoger@....com>
To: Reinette Chatre <reinette.chatre@...el.com>, babu.moger@....com,
 corbet@....net, fenghua.yu@...el.com, tglx@...utronix.de, mingo@...hat.com,
 bp@...en8.de, dave.hansen@...ux.intel.com
Cc: x86@...nel.org, hpa@...or.com, paulmck@...nel.org, rdunlap@...radead.org,
 tj@...nel.org, peterz@...radead.org, yanjiewtw@...il.com,
 kim.phillips@....com, lukas.bulwahn@...il.com, seanjc@...gle.com,
 jmattson@...gle.com, leitao@...ian.org, jpoimboe@...nel.org,
 rick.p.edgecombe@...el.com, kirill.shutemov@...ux.intel.com,
 jithu.joseph@...el.com, kai.huang@...el.com, kan.liang@...ux.intel.com,
 daniel.sneddon@...ux.intel.com, pbonzini@...hat.com, sandipan.das@....com,
 ilpo.jarvinen@...ux.intel.com, peternewman@...gle.com,
 maciej.wieczor-retman@...el.com, linux-doc@...r.kernel.org,
 linux-kernel@...r.kernel.org, eranian@...gle.com, james.morse@....com
Subject: Re: [PATCH v4 16/19] x86/resctrl: Enable ABMC by default on resctrl
 mount

Hi Reinette,

On 6/20/2024 5:49 PM, Reinette Chatre wrote:
> Hi Babu,
> 
> On 6/20/24 7:46 AM, Moger, Babu wrote:
>> On 6/13/24 20:50, Reinette Chatre wrote:
>>> On 5/24/24 5:23 AM, Babu Moger wrote:
> 
> 
>>>> +        if (resctrl_assign_events(&rdtgroup_default) < 0)
>>>> +            rdt_last_cmd_puts("Monitor assignment failed\n");
>>>
>>> How will user know that there is a warning? This does not return an 
>>> error
>>> so nothing will prompt user to check the status file. Perhaps add a 
>>> comment
>>> in the docs to help users at least know that this exists. Another 
>>> helpful
>>
>> Sure. Will add text about this in the documentation.
>>
>>> thing will be to have the counter return "Unassigned" if it has not been
>>> assigned
>>> since users familiar with old interface may see "Unavailable" without
>>> knowing that user action is required to get a working event.
>>
>> Not so sure about interpreting hardware reported error.
>>
> 
> I only see "Unavailable" as a hardware error and that is already
> supported. "Unassigned" is not a hardware error but instead indicates
> to user space that no hardware counter is backing the queried event.
> 

That is fine. Will change to report "Unassinged" when it queried when 
event is not assigned. thanks
-- 
- Babu Moger