linux-kernel - Re: [PATCH v9 8/9] x86/resctrl: Display CLOSID for resource group

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Message-ID: <d0bd1c6f-f1df-5355-5fc8-4fbd3be7d1e2@intel.com>
Date:   Mon, 11 Sep 2023 11:08:27 -0700
From:   Fenghua Yu <fenghua.yu@...el.com>
To:     Babu Moger <babu.moger@....com>, <corbet@....net>,
        <reinette.chatre@...el.com>, <tglx@...utronix.de>,
        <mingo@...hat.com>, <bp@...en8.de>
CC:     <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 v9 8/9] x86/resctrl: Display CLOSID for resource group

Hi, Babu,

On 9/7/23 16:51, Babu Moger wrote:
> In x86, hardware uses CLOSID to identify a control group. When a user
> creates a control group this information is not visible to the user.
> It can help resctrl debugging.
> 
> Add CLOSID(ctrl_hw_id) to the control groups display in resctrl
> interface. Users can see this detail when resctrl is mounted with
> "-o debug" option.
> 
> Other architectures do not use "CLOSID". Use the names ctrl_hw_id
> to refer to "CLOSID" in an effort to keep the naming generic.
> 
> For example:
>   $cat /sys/fs/resctrl/ctrl_grp1/ctrl_hw_id
>   1
> 
> Signed-off-by: Babu Moger <babu.moger@....com>
> ---
>   Documentation/arch/x86/resctrl.rst     |  4 ++++
>   arch/x86/kernel/cpu/resctrl/internal.h |  3 +++
>   arch/x86/kernel/cpu/resctrl/rdtgroup.c | 23 +++++++++++++++++++++++
>   3 files changed, 30 insertions(+)
> 
> diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
> index 28d35aaa74b4..54691c8b832d 100644
> --- a/Documentation/arch/x86/resctrl.rst
> +++ b/Documentation/arch/x86/resctrl.rst
> @@ -352,6 +352,10 @@ When control is enabled all CTRL_MON groups will also contain:
>   	file. On successful pseudo-locked region creation the mode will
>   	automatically change to "pseudo-locked".
>   
> +"ctrl_hw_id":
> +	Available only with debug option. The identifier used by hardware
> +	for the control group. On x86 this is the CLOSID.
> +
>   When monitoring is enabled all MON groups will also contain:
>   
>   "mon_data":
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 38b99a21ccd8..ccdbed615d41 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -299,6 +299,9 @@ struct rdtgroup {
>    *		--> 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 67b315f3a26c..8be0fb323ad3 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -779,6 +779,22 @@ 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;
> +}
> +
>   #ifdef CONFIG_PROC_CPU_RESCTRL
>   
>   /*
> @@ -1863,6 +1879,13 @@ static struct rftype res_common_files[] = {
>   		.seq_show	= rdtgroup_size_show,
>   		.fflags		= RFTYPE_CTRL_BASE,
>   	},
> +	{
> +		.name		= "ctrl_hw_id",
> +		.mode		= 0444,
> +		.kf_ops		= &rdtgroup_kf_single_ops,
> +		.seq_show	= rdtgroup_closid_show,

Is it better to rename "rdtgroup_closid_show" as arch neutral name 
"rdtgroup_ctrl_hw_id_show"? So the name is arch neutral and reflects the 
ctrl_hw_id. So this can eventually go to generic fs code without 
renaming it. The getting closid implementation in the function will be 
arch specific.

> +		.fflags		= RFTYPE_CTRL_BASE | RFTYPE_DEBUG,
> +	},
>   
>   };
>   

Thanks.

-Fenghua