linux-kernel - Re: [PATCH v6 08/22] x86/resctrl: Introduce interface to display number of monitoring counters

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Message-ID: <8ae3edee-47f4-479c-a4a5-cb2e9c2982b8@intel.com>
Date: Tue, 20 Aug 2024 11:08:04 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: <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 v6 08/22] x86/resctrl: Introduce interface to display
 number of monitoring counters

Hi Babu,

On 8/20/24 8:56 AM, Moger, Babu wrote:
> On 8/16/24 16:34, Reinette Chatre wrote:
>> On 8/6/24 3:00 PM, Babu Moger wrote:

>>> diff --git a/Documentation/arch/x86/resctrl.rst
>>> b/Documentation/arch/x86/resctrl.rst
>>> index d4ec605b200a..fe9f10766c4f 100644
>>> --- a/Documentation/arch/x86/resctrl.rst
>>> +++ b/Documentation/arch/x86/resctrl.rst
>>> @@ -291,6 +291,9 @@ with the following files:
>>>            as long as there are enough RMID counters available to support
>>> number
>>>            of monitoring groups.
>>>    +"num_mbm_cntrs":
>>> +    The number of monitoring counters available for assignment.
>>> +
>>>    "max_threshold_occupancy":
>>>            Read/write file provides the largest value (in
>>>            bytes) at which a previously used LLC_occupancy
>>> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c
>>> b/arch/x86/kernel/cpu/resctrl/monitor.c
>>> index 5e8706ab6361..83329cefebf7 100644
>>> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
>>> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
>>> @@ -1242,6 +1242,8 @@ int __init rdt_get_mon_l3_config(struct
>>> rdt_resource *r)
>>>                r->mon.num_mbm_cntrs = (ebx & 0xFFFF) + 1;
>>>                if (WARN_ON(r->mon.num_mbm_cntrs > 64))
>>>                    r->mon.num_mbm_cntrs = 64;
>>> +
>>> +            resctrl_file_fflags_init("num_mbm_cntrs", RFTYPE_MON_INFO);
>>
>> The arch code should not access the resctrl file flags. This should be
>> moved to make
>> the MPAM support easier. With the arch code setting
>> r->mon.mbm_cntr_assignable the
>> fs code can use that to set the flags. Something similar to below patch is
>> needed:
>> https://lore.kernel.org/lkml/20240802172853.22529-27-james.morse@arm.com/
> 
> It is just moving the calls resctrl_file_fflags_init() to resctrl_init().
> The  rdt_resource fields are already setup here. Something like
> https://lore.kernel.org/lkml/20240802172853.22529-20-james.morse@arm.com/
> 
> I feel it is better done when MBAM fs/arch separation.

Indeed, it belongs with the rest of the mon state setup that is organized
as part of the MPAM work.

Reinette