Hi Babu,
There seems to be many places referring to user space assigning "counter IDs",
as I understand the interface the user has no control over the actual ID of the
counter being assigned. Please correct me if I am wrong.
Considering this, how about:
fs/resctrl: Add resctrl file to display number of assignable counters
If you agree, please check the whole series as this seems to be an often
copy&pasted term.
On 6/13/25 2:04 PM, Babu Moger wrote:
> The "mbm_event" mode allows users to assign a hardware counter ID to an
"a hardware counter ID" -> "a hardware counter"?
> RMID, event pair and monitor bandwidth usage as long as it is assigned.
> The hardware continues to track the assigned counter until it is
> explicitly unassigned by the user.
>
> Create 'num_mbm_cntrs' resctrl file that displays the number of counter
> IDs supported in each domain. 'num_mbm_cntrs' is only visible to user
"number of counter IDs" -> "number of counters"?
> space when the system supports "mbm_event" mode.
>
> Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
> ---
...
> ---
> Documentation/filesystems/resctrl.rst | 11 ++++++++++
> fs/resctrl/monitor.c | 4 ++++
> fs/resctrl/rdtgroup.c | 30 +++++++++++++++++++++++++++
> 3 files changed, 45 insertions(+)
>
> diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
> index 4e76e4ac5d3a..801914de0c81 100644
> --- a/Documentation/filesystems/resctrl.rst
> +++ b/Documentation/filesystems/resctrl.rst
> @@ -288,6 +288,17 @@ with the following files:
> result in misleading values or display "Unavailable" if no counter is assigned
> to the event.
>
> +"num_mbm_cntrs":
> + The maximum number of counter IDs (total of available and assigned counters)
"number of counter IDs" -> "number of counters"
> + in each domain when the system supports mbm_event mode.
> +
> + For example, on a system with maximum of 32 memory bandwidth monitoring
> + counters in each of its L3 domains:
> + ::
> +
> + # cat /sys/fs/resctrl/info/L3_MON/num_mbm_cntrs
> + 0=32;1=32
> +
> "max_threshold_occupancy":
> Read/write file provides the largest value (in
> bytes) at which a previously used LLC_occupancy
> diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
> index dcc6c00eb362..92a87aa97b0f 100644
> --- a/fs/resctrl/monitor.c
> +++ b/fs/resctrl/monitor.c
> @@ -924,6 +924,10 @@ int resctrl_mon_resource_init(void)
> else if (resctrl_is_mon_event_enabled(QOS_L3_MBM_TOTAL_EVENT_ID))
> mba_mbps_default_event = QOS_L3_MBM_TOTAL_EVENT_ID;
>
> + if (r->mon.mbm_cntr_assignable)
> + resctrl_file_fflags_init("num_mbm_cntrs",
> + RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
> +
> return 0;
> }
>
> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
> index ba7a9a68c5a6..967e4df62a19 100644
> --- a/fs/resctrl/rdtgroup.c
> +++ b/fs/resctrl/rdtgroup.c
> @@ -1829,6 +1829,30 @@ static int resctrl_mbm_assign_mode_show(struct kernfs_open_file *of,
> return 0;
> }
>
> +static int resctrl_num_mbm_cntrs_show(struct kernfs_open_file *of,
> + struct seq_file *s, void *v)
> +{
> + struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
> + struct rdt_mon_domain *dom;
> + bool sep = false;
> +
> + cpus_read_lock();
> + mutex_lock(&rdtgroup_mutex);
> +
> + list_for_each_entry(dom, &r->mon_domains, hdr.list) {
> + if (sep)
> + seq_putc(s, ';');
> +
> + seq_printf(s, "%d=%d", dom->hdr.id, r->mon.num_mbm_cntrs);
> + sep = true;
> + }
> + seq_putc(s, '\n');
> +
> + mutex_unlock(&rdtgroup_mutex);
> + cpus_read_unlock();
> + return 0;
> +}
> +
> /* rdtgroup information files for one cache resource. */
> static struct rftype res_common_files[] = {
> {
> @@ -1866,6 +1890,12 @@ static struct rftype res_common_files[] = {
> .seq_show = rdt_default_ctrl_show,
> .fflags = RFTYPE_CTRL_INFO | RFTYPE_RES_CACHE,
> },
> + {
> + .name = "num_mbm_cntrs",
> + .mode = 0444,
> + .kf_ops = &rdtgroup_kf_single_ops,
> + .seq_show = resctrl_num_mbm_cntrs_show,
> + },
> {
> .name = "min_cbm_bits",
> .mode = 0444,
Patch looks good.
Reinette
