linux-kernel - Re: [RFC v2 PATCH 5/7] x86/resctrl: Introduce -o debug mount option

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Message-ID: <04a598d8-eeee-9512-7db9-cfeae33999a7@intel.com>
Date:   Thu, 16 Feb 2023 17:42:43 -0800
From:   Fenghua Yu <fenghua.yu@...el.com>
To:     Babu Moger <babu.moger@....com>, <reinette.chatre@...el.com>
CC:     <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
        <dave.hansen@...ux.intel.com>, <x86@...nel.org>, <hpa@...or.com>,
        <corbet@....net>, <linux-kernel@...r.kernel.org>,
        <linux-doc@...r.kernel.org>, <eranian@...gle.com>,
        <peternewman@...gle.com>
Subject: Re: [RFC v2 PATCH 5/7] x86/resctrl: Introduce -o debug mount option

Hi, Babu,

On 2/2/23 13:47, Babu Moger wrote:
> Add -o debug option to mount resctrl filesystem in debug mode. Debug
> option adds the files for debug purposes.
> 
> Signed-off-by: Babu Moger <babu.moger@....com>
> ---
>   Documentation/x86/resctrl.rst          |    2 ++
>   arch/x86/kernel/cpu/resctrl/internal.h |    1 +
>   arch/x86/kernel/cpu/resctrl/rdtgroup.c |    7 +++++++
>   3 files changed, 10 insertions(+)
> 
> diff --git a/Documentation/x86/resctrl.rst b/Documentation/x86/resctrl.rst
> index 58b76fc75cb7..2c013c5d45fd 100644
> --- a/Documentation/x86/resctrl.rst
> +++ b/Documentation/x86/resctrl.rst
> @@ -46,6 +46,8 @@ mount options are:
>   "mba_MBps":
>   	Enable the MBA Software Controller(mba_sc) to specify MBA
>   	bandwidth in MBps
> +"debug":
> +	Lists the debug files in resctrl interface
>   
>   L2 and L3 CDP are controlled separately.
>   
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 6767c85b9699..35a9ee343fe0 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -59,6 +59,7 @@ struct rdt_fs_context {
>   	bool				enable_cdpl2;
>   	bool				enable_cdpl3;
>   	bool				enable_mba_mbps;
> +	bool				debug;
>   };
>   
>   static inline struct rdt_fs_context *rdt_fc2context(struct fs_context *fc)
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 18d458a3cba6..9b7813aa6baf 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -2555,6 +2555,7 @@ enum rdt_param {
>   	Opt_cdp,
>   	Opt_cdpl2,
>   	Opt_mba_mbps,
> +	Opt_debug,
>   	nr__rdt_params
>   };
>   
> @@ -2562,6 +2563,7 @@ static const struct fs_parameter_spec rdt_fs_parameters[] = {
>   	fsparam_flag("cdp",		Opt_cdp),
>   	fsparam_flag("cdpl2",		Opt_cdpl2),
>   	fsparam_flag("mba_MBps",	Opt_mba_mbps),
> +	fsparam_flag("debug",		Opt_debug),
>   	{}
>   };
>   
> @@ -2587,6 +2589,9 @@ static int rdt_parse_param(struct fs_context *fc, struct fs_parameter *param)
>   			return -EINVAL;
>   		ctx->enable_mba_mbps = true;
>   		return 0;
> +	case Opt_debug:
> +		ctx->debug = true;
> +		return 0;
>   	}
>   
>   	return -EINVAL;
> @@ -3525,6 +3530,8 @@ static int rdtgroup_show_options(struct seq_file *seq, struct kernfs_root *kf)
>   	if (is_mba_sc(&rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl))
>   		seq_puts(seq, ",mba_MBps");
>   
> +	seq_puts(seq, ",debug");

Need to add a check here otherwise ",debug" will be always shown 
regardless "-o debug" is given or not:
+	if (ctx->debug)
+		seq_puts(seq, ",debug");

But I don't know a good way to get ctx->debug in this function yet. I 
think somehow ctx can be retrieved from kf but not sure.

> +
>   	return 0;
>   }
>   
> 
> 
Thanks.

-Fenghua