Re: [PATCH v13 23/27] x86/resctrl: Introduce mbm_L3_assignments to list assignments in a group

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

Hi Babu,

On 5/15/25 3:52 PM, Babu Moger wrote:
> Introduce the interface to display the assignment states for each group
> when mbm_cntr_assign mode is enabled.
> 
> The list is displayed in the following format:
> <Event configuration>:<Domain id>=<Assignment type>

Should this just be <Event>? The information is just the event name, not
its configuration that will be in the "event_filter" file.

> 
> Event configuration: A valid event configuration listed in the
> /sys/fs/resctrl/info/L3_MON/counter_configs directory.
> 
> Domain ID: A valid domain ID number.
> 
> The assignment type can be one of the following:
> 
> _ : No event configuration assigned
> 
> e : Event configuration assigned in exclusive mode
> 
> Example:
> $cd /sys/fs/resctrl
> $cat 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>
> ---
> 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                 | 52 +++++++++++++++++++++++++++
>  3 files changed, 81 insertions(+)
> 
> diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
> index 356f1f918a86..2350c1f21f4e 100644
> --- a/Documentation/filesystems/resctrl.rst
> +++ b/Documentation/filesystems/resctrl.rst
> @@ -504,6 +504,34 @@ 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":
> +	This interface file is created when the mbm_cntr_assign mode is supported

"This interface file is created when" -> "Exists when mbm_cntr_assign mode is supported"?

> +	and shows the assignment status for each group.

This doc is in the portion documenting files in monitor groups. So rather:
"the assignment status for each group" -> "the counter assignment status for the MON group"?

> +
> +	The assignment list is displayed in the following format:
> +
> +	<Event configuration>:<Domain id>=<Assignment type>

<Event configuration> -> <Event>

> +
> +	Event configuration: A valid event configuration listed in the

"A valid event in the /sys/fs/resctrl/info/L3_MON/event_configs directory"

> +	/sys/fs/resctrl/info/L3_MON/counter_configs directory.
> +
> +	Domain ID: A valid domain ID number.

"A valid domain ID"

> +
> +	Assignment types:
> +
> +	_ : No event configuration assigned

hmmm ... since the line has event as first field, would this not reflect the
counter? That is "No counter assigned"

> +
> +	e : Event configuration assigned in exclusive mode

"Counter assigned exclusively"? (with exclusive defined somewhere)

> +
> +	Example:
> +	To list the assignment states for the default group.

"the counter assignment states"?

> +	::
> +
> +	  # cd /sys/fs/resctrl
> +	  # cat 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 5f6c4b662f3b..b982540ce4e3 100644
> --- a/fs/resctrl/monitor.c
> +++ b/fs/resctrl/monitor.c
> @@ -935,6 +935,7 @@ 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 931ea355f159..8d970b99bbbd 100644
> --- a/fs/resctrl/rdtgroup.c
> +++ b/fs/resctrl/rdtgroup.c
> @@ -2080,6 +2080,52 @@ 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)
> +		return -ENOENT;

Missing a rdtgroup_kn_unlock()?

> +
> +	rdt_last_cmd_clear();
> +	if (!resctrl_arch_mbm_cntr_assign_enabled(r)) {
> +		rdt_last_cmd_puts("mbm_cntr_assign mode not enabled\n");
> +		ret = -ENOENT;
> +		goto assign_out;

grep goto fs/resctrl/rdtgroup.c

> +	}
> +
> +	list_for_each_entry(mevt, &r->mon.evt_list, list) {

can use for_each_mbm_event() and then below will not be needed?

> +		if (mevt->mbm_mode != MBM_MODE_ASSIGN)
> +			continue;
> +
> +		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');
> +	}
> +
> +assign_out:
> +	rdtgroup_kn_unlock(of->kn);
> +
> +	return ret;
> +}
> +
>  /* rdtgroup information files for one cache resource. */
>  static struct rftype res_common_files[] = {
>  	{
> @@ -2218,6 +2264,12 @@ 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