From: Babu Moger Date: Fri, 5 Sep 2025 21:34:10 +0000 (-0500) Subject: fs/resctrl: Add resctrl file to display number of assignable counters X-Git-Tag: v6.18-rc1~186^2~23 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=8c793336eaf8893a29626155d74615fe9f03e7f2;p=thirdparty%2Flinux.git fs/resctrl: Add resctrl file to display number of assignable counters The "mbm_event" counter assignment mode allows users to assign a hardware counter to an 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 counters supported in each domain. 'num_mbm_cntrs' is only visible to user space when the system supports "mbm_event" mode. Signed-off-by: Babu Moger Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Reinette Chatre Link: https://lore.kernel.org/cover.1757108044.git.babu.moger@amd.com --- diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst index b692829fec5f6..4eb27530be6ff 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 counters (total of available and assigned 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/internal.h b/fs/resctrl/internal.h index 78aeb7ea38af2..7a12187eced82 100644 --- a/fs/resctrl/internal.h +++ b/fs/resctrl/internal.h @@ -386,6 +386,8 @@ void *rdt_kn_parent_priv(struct kernfs_node *kn); int resctrl_mbm_assign_mode_show(struct kernfs_open_file *of, struct seq_file *s, void *v); +int resctrl_num_mbm_cntrs_show(struct kernfs_open_file *of, struct seq_file *s, void *v); + #ifdef CONFIG_RESCTRL_FS_PSEUDO_LOCK int rdtgroup_locksetup_enter(struct rdtgroup *rdtgrp); diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c index 96231d517e711..112979e9c4445 100644 --- a/fs/resctrl/monitor.c +++ b/fs/resctrl/monitor.c @@ -912,6 +912,30 @@ int resctrl_mbm_assign_mode_show(struct kernfs_open_file *of, return 0; } +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; +} + /** * resctrl_mon_resource_init() - Initialise global monitoring structures. * @@ -957,6 +981,8 @@ int resctrl_mon_resource_init(void) resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID); if (!resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID)) resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID); + 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 144585a859967..9d95d01da3f9d 100644 --- a/fs/resctrl/rdtgroup.c +++ b/fs/resctrl/rdtgroup.c @@ -1836,6 +1836,12 @@ 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,