Re: [PATCH v14 28/32] fs/resctrl: Introduce mbm_L3_assignments to list assignments in a group

[Reinette Chatre <reinette.chatre@intel.com>]

Hi Babu,

On 6/13/25 2:05 PM, Babu Moger wrote:
> Introduce the interface to display the assignment states for resctrl group

"Introduce the mbm_L3_assignments resctrl file associated with
CTRL_MON an MON resource groups to display the counter assignment
states of the resource group when "mbm_event" counter assignment
mode is enabled."

> when "mbm_event" mdoe is enabled.

"mdoe" -> "counter assignment mode"

> 
> The list is displayed in the following format:
> <Event>:<Domain id>=<Assignment state>

Similar to previous note, please add syntax for multiple domains to avoid
it appearing that each domain is on one line.

> 
> Event: A valid MBM event listed in
>        /sys/fs/resctrl/info/L3_MON/event_configs directory.
> 
> Domain ID: A valid domain ID.
> 
> The assignment state can be one of the following:
> 
> _ : No counter assigned.
> 
> e : Counter assigned exclusively.
> 
> Example:
> To list the assignment states for the default group
> $ cd /sys/fs/resctrl
> $ cat /sys/fs/resctrl/mbm_L3_assignments
> mbm_total_bytes:0=e;1=e
> mbm_local_bytes:0=e;1=e
> 
> Signed-off-by: Babu Moger <babu.moger@amd.com>
> ---
> v14: Added missed rdtgroup_kn_lock_live on failure case.
>      Updated the user doc resctrl.rst to clarify counter assignments.
>      Updated the changelog.
> 
> v13: Changelog update.
>      Few changes in mbm_L3_assignments_show() after moving the event config to evt_list.
>      Resolved conflicts caused by the recent FS/ARCH code restructure.
>      The rdtgroup.c/monitor.c files have been split between the FS and ARCH directories.
> 
> v12: New patch:
>      Assignment interface moved inside the group based the discussion
>      https://lore.kernel.org/lkml/CALPaoCiii0vXOF06mfV=kVLBzhfNo0SFqt4kQGwGSGVUqvr2Dg@mail.gmail.com/#t
> ---
>  Documentation/filesystems/resctrl.rst | 28 ++++++++++++++
>  fs/resctrl/monitor.c                  |  1 +
>  fs/resctrl/rdtgroup.c                 | 54 +++++++++++++++++++++++++++
>  3 files changed, 83 insertions(+)
> 
> diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
> index f94c7c387416..a232a0b1356c 100644
> --- a/Documentation/filesystems/resctrl.rst
> +++ b/Documentation/filesystems/resctrl.rst
> @@ -516,6 +516,34 @@ When the "mba_MBps" mount option is used all CTRL_MON groups will also contain:
>  	/sys/fs/resctrl/info/L3_MON/mon_features changes the input
>  	event.
>  
> +"mbm_L3_assignments":
> +	Exists when "mbm_event" mode is supported and lists the counter

""mbm_event" mode" -> "mbm_event" counter assignment mode"

> +	assignment states for the group.

"for the group" -> "of the group"?

> +
> +	The assignment list is displayed in the following format:
> +
> +	<Event>:<Domain ID>=<Assignment state>

Same comment about syntax example.

> +
> +	Event: A valid MBM event in the
> +	       /sys/fs/resctrl/info/L3_MON/event_configs directory.
> +
> +	Domain ID: A valid domain ID.
> +
> +	Assignment states:
> +
> +	_ : No counter assigned.
> +
> +	e : Counter assigned exclusively.
> +
> +	Example:
> +	To display the counter assignment states for the default group.
> +	::
> +
> +	 # cd /sys/fs/resctrl
> +	 # cat /sys/fs/resctrl/mbm_L3_assignments
> +	   mbm_total_bytes:0=e;1=e
> +	   mbm_local_bytes:0=e;1=e
> +
>  Resource allocation rules
>  -------------------------
>  
> diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
> index 1ec2efd50273..618c94cd1ad8 100644
> --- a/fs/resctrl/monitor.c
> +++ b/fs/resctrl/monitor.c
> @@ -959,6 +959,7 @@ int resctrl_mon_resource_init(void)
>  		resctrl_file_fflags_init("event_filter", RFTYPE_ASSIGN_CONFIG);
>  		resctrl_file_fflags_init("mbm_assign_on_mkdir", RFTYPE_MON_INFO |
>  					 RFTYPE_RES_CACHE);
> +		resctrl_file_fflags_init("mbm_L3_assignments", RFTYPE_MON_BASE);
>  	}
>  
>  	return 0;
> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
> index 128a9db339f3..18ec65801dbb 100644
> --- a/fs/resctrl/rdtgroup.c
> +++ b/fs/resctrl/rdtgroup.c
> @@ -2081,6 +2081,54 @@ static ssize_t resctrl_mbm_assign_on_mkdir_write(struct kernfs_open_file *of,
>  	return ret ?: nbytes;
>  }
>  
> +static int mbm_L3_assignments_show(struct kernfs_open_file *of, struct seq_file *s, void *v)
> +{
> +	struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
> +	struct rdt_mon_domain *d;
> +	struct rdtgroup *rdtgrp;
> +	struct mon_evt *mevt;
> +	int ret = 0;
> +	bool sep;
> +
> +	rdtgrp = rdtgroup_kn_lock_live(of->kn);
> +	if (!rdtgrp) {
> +		ret = -ENOENT;
> +		goto out_assign;

out_assign -> out_unlock

> +	}
> +
> +	rdt_last_cmd_clear();
> +	if (!resctrl_arch_mbm_cntr_assign_enabled(r)) {
> +		rdt_last_cmd_puts("mbm_event mode is not enabled\n");
> +		ret = -ENOENT;
> +		goto out_assign;
> +	}
> +
> +	for (mevt = &mon_event_all[0]; mevt < &mon_event_all[QOS_NUM_EVENTS]; mevt++) {
> +		if (!mevt->enabled || !resctrl_is_mbm_event(mevt->evtid))
> +			continue;

(use macro and mon_evt::rid)

> +
> +		sep = false;
> +		seq_printf(s, "%s:", mevt->name);
> +		list_for_each_entry(d, &r->mon_domains, hdr.list) {
> +			if (sep)
> +				seq_putc(s, ';');
> +
> +			if (mbm_cntr_get(r, d, rdtgrp, mevt->evtid) >= 0)
> +				seq_printf(s, "%d=e", d->hdr.id);
> +			else
> +				seq_printf(s, "%d=_", d->hdr.id);
> +
> +			sep = true;
> +		}
> +		seq_putc(s, '\n');
> +	}
> +
> +out_assign:
> +	rdtgroup_kn_unlock(of->kn);
> +
> +	return ret;
> +}
> +
>  /* rdtgroup information files for one cache resource. */
>  static struct rftype res_common_files[] = {
>  	{
> @@ -2219,6 +2267,12 @@ static struct rftype res_common_files[] = {
>  		.seq_show	= event_filter_show,
>  		.write		= event_filter_write,
>  	},
> +	{
> +		.name		= "mbm_L3_assignments",
> +		.mode		= 0444,
> +		.kf_ops		= &rdtgroup_kf_single_ops,
> +		.seq_show	= mbm_L3_assignments_show,
> +	},
>  	{
>  		.name		= "mbm_assign_mode",
>  		.mode		= 0444,

Reinette