diff mbox series

[v5,5/8] x86/resctrl: Introduce "-o debug" mount option

Message ID 168564610093.527584.3413729327027786408.stgit@bmoger-ubuntu
State New
Headers
Series x86/resctrl: Miscellaneous resctrl features |

Commit Message

Moger, Babu June 1, 2023, 7:01 p.m. UTC 
  Add "-o debug" option to mount resctrl filesystem in debug mode.
This option can be used for adding extra files to help debug
resctrl issues.

For example, hardware uses CLOSID and RMIDs to control and monitor
resctrl resources. These numbers are not visible to the user. These
details can help to debug issues. Debug option provides a method to
add these files to resctrl.

Signed-off-by: Babu Moger <babu.moger@amd.com>
---
 Documentation/arch/x86/resctrl.rst     |    3 +++
 arch/x86/kernel/cpu/resctrl/internal.h |    1 +
 arch/x86/kernel/cpu/resctrl/rdtgroup.c |   15 +++++++++++++++
 3 files changed, 19 insertions(+)

Comments

Reinette Chatre July 7, 2023, 9:42 p.m. UTC | #1 
Hi Babu,

On 6/1/2023 12:01 PM, Babu Moger wrote:
> Add "-o debug" option to mount resctrl filesystem in debug mode.
> This option can be used for adding extra files to help debug
> resctrl issues.

Please avoid uncertainty in the changelog (re. "can be used"). I
think it will help to be more specific if the first and last
hunks of patch 8 is merged into this patch, making it clear
that the debug mount option is in support of debug files with
this changelog written to support that.

> For example, hardware uses CLOSID and RMIDs to control and monitor
> resctrl resources. These numbers are not visible to the user. These
> details can help to debug issues. Debug option provides a method to
> add these files to resctrl.

With the debug file support added here this extra motivation should
not be necessary (remaining hunks of patch 8 can be moved to where
these files are introduced).
> 
> Signed-off-by: Babu Moger <babu.moger@amd.com>
> ---
>  Documentation/arch/x86/resctrl.rst     |    3 +++
>  arch/x86/kernel/cpu/resctrl/internal.h |    1 +
>  arch/x86/kernel/cpu/resctrl/rdtgroup.c |   15 +++++++++++++++
>  3 files changed, 19 insertions(+)
> 
> diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
> index 290f01aa3002..afdee4d1f691 100644
> --- a/Documentation/arch/x86/resctrl.rst
> +++ b/Documentation/arch/x86/resctrl.rst
> @@ -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".
>  

At the risk of becoming unreadable, the earlier documentation of the mount
command should also change.

>  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 c20cd6acb7a3..c07c6517d856 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)
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index baed20b2d788..be91dea5f927 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -56,6 +56,8 @@ static char last_cmd_status_buf[512];
>  
>  struct dentry *debugfs_resctrl;
>  
> +static bool resctrl_debug;
> +
>  void rdt_last_cmd_clear(void)
>  {
>  	lockdep_assert_held(&rdtgroup_mutex);
> @@ -2368,6 +2370,9 @@ static int rdt_enable_ctx(struct rdt_fs_context *ctx)
>  	if (!ret && ctx->enable_mba_mbps)
>  		ret = set_mba_sc(true);
>  
> +	if (!ret && ctx->enable_debug)
> +		resctrl_debug = true;
> +
>  	return ret;
>  }

Looks like unwinding of rdt_enable_ctx() errors is done in the caller, this is
not ideal and additions like above cause some error unwinding to be omitted.
I cannot see why rdt_enable_ctx() cannot do its own error unwinding. This
may be better as a separate patch.

Reinette
Moger, Babu July 12, 2023, 4:40 p.m. UTC | #2 
Hi Reinette,

On 7/7/23 16:42, Reinette Chatre wrote:
> Hi Babu,
> 
> On 6/1/2023 12:01 PM, Babu Moger wrote:
>> Add "-o debug" option to mount resctrl filesystem in debug mode.
>> This option can be used for adding extra files to help debug
>> resctrl issues.
> 
> Please avoid uncertainty in the changelog (re. "can be used"). I

ok Sure.

> think it will help to be more specific if the first and last
> hunks of patch 8 is merged into this patch, making it clear
> that the debug mount option is in support of debug files with
> this changelog written to support that.

Sure. Will do that.

> 
>> For example, hardware uses CLOSID and RMIDs to control and monitor
>> resctrl resources. These numbers are not visible to the user. These
>> details can help to debug issues. Debug option provides a method to
>> add these files to resctrl.
> 
> With the debug file support added here this extra motivation should
> not be necessary (remaining hunks of patch 8 can be moved to where
> these files are introduced).

Sure.

>>
>> Signed-off-by: Babu Moger <babu.moger@amd.com>
>> ---
>>  Documentation/arch/x86/resctrl.rst     |    3 +++
>>  arch/x86/kernel/cpu/resctrl/internal.h |    1 +
>>  arch/x86/kernel/cpu/resctrl/rdtgroup.c |   15 +++++++++++++++
>>  3 files changed, 19 insertions(+)
>>
>> diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
>> index 290f01aa3002..afdee4d1f691 100644
>> --- a/Documentation/arch/x86/resctrl.rst
>> +++ b/Documentation/arch/x86/resctrl.rst
>> @@ -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".
>>  
> 
> At the risk of becoming unreadable, the earlier documentation of the mount
> command should also change.

Ok. Sure

> 
>>  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 c20cd6acb7a3..c07c6517d856 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)
>> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> index baed20b2d788..be91dea5f927 100644
>> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> @@ -56,6 +56,8 @@ static char last_cmd_status_buf[512];
>>  
>>  struct dentry *debugfs_resctrl;
>>  
>> +static bool resctrl_debug;
>> +
>>  void rdt_last_cmd_clear(void)
>>  {
>>  	lockdep_assert_held(&rdtgroup_mutex);
>> @@ -2368,6 +2370,9 @@ static int rdt_enable_ctx(struct rdt_fs_context *ctx)
>>  	if (!ret && ctx->enable_mba_mbps)
>>  		ret = set_mba_sc(true);
>>  
>> +	if (!ret && ctx->enable_debug)
>> +		resctrl_debug = true;
>> +
>>  	return ret;
>>  }
> 
> Looks like unwinding of rdt_enable_ctx() errors is done in the caller, this is
> not ideal and additions like above cause some error unwinding to be omitted.
> I cannot see why rdt_enable_ctx() cannot do its own error unwinding. This
> may be better as a separate patch.
> 

Sure. Will do error unwinding of rdt_enable_ctx as a separate patch before
this patch. That seems more appropriate.
diff mbox series

Patch

diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index 290f01aa3002..afdee4d1f691 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -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 c20cd6acb7a3..c07c6517d856 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)
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index baed20b2d788..be91dea5f927 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -56,6 +56,8 @@  static char last_cmd_status_buf[512];
 
 struct dentry *debugfs_resctrl;
 
+static bool resctrl_debug;
+
 void rdt_last_cmd_clear(void)
 {
 	lockdep_assert_held(&rdtgroup_mutex);
@@ -2368,6 +2370,9 @@  static int rdt_enable_ctx(struct rdt_fs_context *ctx)
 	if (!ret && ctx->enable_mba_mbps)
 		ret = set_mba_sc(true);
 
+	if (!ret && ctx->enable_debug)
+		resctrl_debug = true;
+
 	return ret;
 }
 
@@ -2556,6 +2561,7 @@  enum rdt_param {
 	Opt_cdp,
 	Opt_cdpl2,
 	Opt_mba_mbps,
+	Opt_debug,
 	nr__rdt_params
 };
 
@@ -2563,6 +2569,7 @@  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),
 	{}
 };
 
@@ -2588,6 +2595,9 @@  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;
@@ -2778,6 +2788,8 @@  static void rdt_kill_sb(struct super_block *sb)
 
 	set_mba_sc(false);
 
+	resctrl_debug = false;
+
 	/*Put everything back to default values. */
 	for_each_alloc_capable_rdt_resource(r)
 		reset_all_ctrls(r);
@@ -3530,6 +3542,9 @@  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;
 }