linux-kernel - Re: [PATCH v8 8/8] x86/resctrl: Display hardware ids of resource groups

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Message-ID: <da47698a-aa9e-3760-1321-5ec3ea1a14e6@amd.com>
Date:   Wed, 30 Aug 2023 18:19:01 -0500
From:   "Moger, Babu" <babu.moger@....com>
To:     Reinette Chatre <reinette.chatre@...el.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 v8 8/8] x86/resctrl: Display hardware ids of resource
 groups

Hi Reinette,

On 8/29/23 15:14, Reinette Chatre wrote:
> Hi Babu,
> 
> On 8/21/2023 4:30 PM, Babu Moger wrote:
> 
> ...
> 
>> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
>> index 2fae6d9e24d3..3fa32c1c2677 100644
>> --- a/arch/x86/kernel/cpu/resctrl/internal.h
>> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
>> @@ -296,9 +296,15 @@ struct rdtgroup {
>>   *	--> RFTYPE_BASE (Files common for both MON and CTRL groups)
>>   *	    Files: cpus, cpus_list, tasks
>>   *
>> + *		--> RFTYPE_DEBUG (Files to help resctrl debugging)
>> + *		    File: mon_hw_id
>> + *
> 
> This does not look right. I think mon_hw_id should have RFTYPE_MON
> (more below).

I am not sure about this (more below).

> 
>>   *		--> RFTYPE_CTRL (Files only for CTRL group)
>>   *		    Files: mode, schemata, size
>>   *
>> + *			--> RFTYPE_DEBUG (Files to help resctrl debugging)
>> + *			    File: ctrl_hw_id
>> + *
>>   */
>>  #define RFTYPE_INFO			BIT(0)
>>  #define RFTYPE_BASE			BIT(1)
>> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> index 94bd69f9964c..e0c2479acf49 100644
>> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> @@ -776,6 +776,38 @@ static int rdtgroup_tasks_show(struct kernfs_open_file *of,
>>  	return ret;
>>  }
>>  
>> +static int rdtgroup_closid_show(struct kernfs_open_file *of,
>> +				struct seq_file *s, void *v)
>> +{
>> +	struct rdtgroup *rdtgrp;
>> +	int ret = 0;
>> +
>> +	rdtgrp = rdtgroup_kn_lock_live(of->kn);
>> +	if (rdtgrp)
>> +		seq_printf(s, "%u\n", rdtgrp->closid);
>> +	else
>> +		ret = -ENOENT;
>> +	rdtgroup_kn_unlock(of->kn);
>> +
>> +	return ret;
>> +}
>> +
>> +static int rdtgroup_rmid_show(struct kernfs_open_file *of,
>> +			      struct seq_file *s, void *v)
>> +{
>> +	struct rdtgroup *rdtgrp;
>> +	int ret = 0;
>> +
>> +	rdtgrp = rdtgroup_kn_lock_live(of->kn);
>> +	if (rdtgrp)
>> +		seq_printf(s, "%u\n", rdtgrp->mon.rmid);
>> +	else
>> +		ret = -ENOENT;
>> +	rdtgroup_kn_unlock(of->kn);
>> +
>> +	return ret;
>> +}
>> +
>>  #ifdef CONFIG_PROC_CPU_RESCTRL
>>  
>>  /*
>> @@ -1837,6 +1869,13 @@ static struct rftype res_common_files[] = {
>>  		.seq_show	= rdtgroup_tasks_show,
>>  		.fflags		= RFTYPE_BASE,
>>  	},
>> +	{
>> +		.name		= "mon_hw_id",
>> +		.mode		= 0444,
>> +		.kf_ops		= &rdtgroup_kf_single_ops,
>> +		.seq_show	= rdtgroup_rmid_show,
>> +		.fflags		= RFTYPE_BASE | RFTYPE_DEBUG,
> 
> I missed this earlier but I think this also needs a RFTYPE_MON.
> Perhaps patch 3 can introduce a new RFTYPE_MON_BASE to not
> have the flags of the two new files look too different?

We have two types of files in base directory structure.

 if (rtype == RDTCTRL_GROUP)
                files = RFTYPE_BASE | RFTYPE_CTRL;
        else
                files = RFTYPE_BASE | RFTYPE_MON;

1. RFTYPE_BASE | RFTYPE_CTRL;
   Files for the control group only.

2. RFTYPE_BASE | RFTYPE_MON;
   Files for both control and mon groups. However, RFTYPE_MON is not used
for any files. It is only RFTYPE_BASE.

Because of the check in rdtgroup_add_files it all works fine.
For the control group it creates files with RFTYPE_BASE | RFTYPE_CTRL and
RFTYPE_BASE.

For the mon group it creates files with RFTYPE_BASE only.

Adding FTYPE_MON_BASE will be a problem.

-- 
Thanks
Babu Moger