Re: [PATCH v10 07/10] x86/resctrl: Introduce "-o debug" mount option

[Ilpo Järvinen]

On Fri, 15 Sep 2023, Babu Moger wrote:

> Add "-o debug" option to mount resctrl filesystem in debug mode.
> When in debug mode resctrl displays files that have the new
> RFTYPE_DEBUG flag to help resctrl debugging.
> 
> Reviewed-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
> Reviewed-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
> Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
> ---
>  Documentation/arch/x86/resctrl.rst     |  5 ++++-
>  arch/x86/kernel/cpu/resctrl/internal.h |  2 ++
>  arch/x86/kernel/cpu/resctrl/rdtgroup.c | 18 ++++++++++++++++++
>  3 files changed, 24 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
> index 8154e9975d1e..28d35aaa74b4 100644
> --- a/Documentation/arch/x86/resctrl.rst
> +++ b/Documentation/arch/x86/resctrl.rst
> @@ -35,7 +35,7 @@ about the feature from resctrl's info directory.
>  
>  To use the feature mount the file system::
>  
> - # mount -t resctrl resctrl [-o cdp[,cdpl2][,mba_MBps]] /sys/fs/resctrl
> + # mount -t resctrl resctrl [-o cdp[,cdpl2][,mba_MBps][,debug]] /sys/fs/resctrl
>  
>  mount options are:
>  
> @@ -46,6 +46,9 @@ mount options are:
>  "mba_MBps":
>  	Enable the MBA Software Controller(mba_sc) to specify MBA
>  	bandwidth in MBps
> +"debug":
> +	Make debug files accessible. Available debug files are annotated with
> +	"Available only with debug option".
>  
>  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 14988c9f402c..68d1b7147291 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				enable_debug;
>  };
>  
>  static inline struct rdt_fs_context *rdt_fc2context(struct fs_context *fc)
> @@ -306,6 +307,7 @@ struct rdtgroup {
>  #define RFTYPE_TOP			BIT(6)
>  #define RFTYPE_RES_CACHE		BIT(8)
>  #define RFTYPE_RES_MB			BIT(9)
> +#define RFTYPE_DEBUG			BIT(10)
>  #define RFTYPE_CTRL_INFO		(RFTYPE_INFO | RFTYPE_CTRL)
>  #define RFTYPE_MON_INFO			(RFTYPE_INFO | RFTYPE_MON)
>  #define RFTYPE_TOP_INFO			(RFTYPE_INFO | RFTYPE_TOP)
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index a34657f0bd0c..150105c21fee 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -59,6 +59,8 @@ static void rdtgroup_destroy_root(void);
>  
>  struct dentry *debugfs_resctrl;
>  
> +static bool resctrl_debug;
> +
>  void rdt_last_cmd_clear(void)
>  {
>  	lockdep_assert_held(&rdtgroup_mutex);
> @@ -1874,6 +1876,9 @@ static int rdtgroup_add_files(struct kernfs_node *kn, unsigned long fflags)
>  
>  	lockdep_assert_held(&rdtgroup_mutex);
>  
> +	if (resctrl_debug)
> +		fflags |= RFTYPE_DEBUG;
> +
>  	for (rft = rfts; rft < rfts + len; rft++) {
>  		if (rft->fflags && ((fflags & rft->fflags) == rft->fflags)) {
>  			ret = rdtgroup_add_file(kn, rft);
> @@ -2377,6 +2382,8 @@ static void rdt_disable_ctx(void)
>  	resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L3, false);
>  	resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L2, false);
>  	set_mba_sc(false);
> +
> +	resctrl_debug = false;
>  }
>  
>  static int rdt_enable_ctx(struct rdt_fs_context *ctx)
> @@ -2401,6 +2408,9 @@ static int rdt_enable_ctx(struct rdt_fs_context *ctx)
>  			goto out_cdpl3;
>  	}
>  
> +	if (ctx->enable_debug)
> +		resctrl_debug = true;
> +
>  	return 0;
>  
>  out_cdpl3:
> @@ -2605,6 +2615,7 @@ enum rdt_param {
>  	Opt_cdp,
>  	Opt_cdpl2,
>  	Opt_mba_mbps,
> +	Opt_debug,
>  	nr__rdt_params
>  };
>  
> @@ -2612,6 +2623,7 @@ 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),
>  	{}
>  };
>  
> @@ -2637,6 +2649,9 @@ 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->enable_debug = true;
> +		return 0;
>  	}
>  
>  	return -EINVAL;
> @@ -3705,6 +3720,9 @@ 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");
>  
> +	if (resctrl_debug)
> +		seq_puts(seq, ",debug");
> +
>  	return 0;
>  }
>  
> 

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>

-- 
 i.