linux-kernel - Re: [PATCH v10 08/10] x86/resctrl: Display CLOSID for resource group

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Message-ID: <77ffcd20-7bae-2017-a0d8-865d13434658@linux.intel.com>
Date:   Fri, 29 Sep 2023 18:40:29 +0300 (EEST)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Babu Moger <babu.moger@....com>
cc:     corbet@....net, reinette.chatre@...el.com, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, fenghua.yu@...el.com,
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Subject: Re: [PATCH v10 08/10] x86/resctrl: Display CLOSID for resource
 group

On Fri, 15 Sep 2023, 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 68d1b7147291..a07fa4329b65 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 150105c21fee..953b082cec8a 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,
> +		.fflags		= RFTYPE_CTRL_BASE | RFTYPE_DEBUG,
> +	},
>  
>  };

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>

-- 
 i.