The BMEC (Bandwidth Monitoring Event Configuration) feature enables
per-domain event configuration. With BMEC the MBM events are configured
using the mbm_total_bytes_config or mbm_local_bytes_config files in
/sys/fs/resctrl/info/L3_MON/ and the per-domain event configuration affects
all monitor resource groups.
The mbm_event counter assignment mode enables counters to be assigned to
RMID (i.e a monitor resource group), event pairs, with potentially unique
event configurations associated with every counter.
There may be systems that support both BMEC and mbm_event counter
assignment mode, but resctrl supporting both concurrently will present a
conflicting interface to the user with both per-domain and per RMID, event
configurations active at the same time.
The mbm_event counter assignment provides most flexibility to user space
and aligns with Arm's counter support. On systems that support both,
disable BMEC event configuration when mbm_event mode is enabled by hiding
the mbm_total_bytes_config or mbm_local_bytes_config files when mbm_event
mode is enabled. Ensure mon_features always displays accurate information
about monitor features.
Suggested-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
---
v15: Updated the changelog.
Moved resctrl_bmec_files_show() inside rdtgroup_mkdir_info_resdir().
Removed the unnecessary kernfs_get() call.
v14: Updated the changelog for change in mbm_assign_modes.
Added check in rdt_mon_features_show to hide bmec related feature.
v13: New patch to hide BMEC related files.
---
fs/resctrl/rdtgroup.c | 39 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 38 insertions(+), 1 deletion(-)
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index b26baca389bb..d73057b96d1d 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -1152,7 +1152,8 @@ static int rdt_mon_features_show(struct kernfs_open_file *of,
if (mevt->rid != r->rid || !mevt->enabled)
continue;
seq_printf(seq, "%s\n", mevt->name);
- if (mevt->configurable)
+ if (mevt->configurable &&
+ !resctrl_arch_mbm_cntr_assign_enabled(r))
seq_printf(seq, "%s_config\n", mevt->name);
}
@@ -1801,6 +1802,36 @@ static ssize_t mbm_local_bytes_config_write(struct kernfs_open_file *of,
return ret ?: nbytes;
}
+/*
+ * resctrl_bmec_files_show() — Controls the visibility of BMEC-related resctrl
+ * files. When @show is true, the files are displayed; when false, the files
+ * are hidden.
+ */
+static void resctrl_bmec_files_show(struct rdt_resource *r, bool show)
+{
+ struct kernfs_node *kn_config, *l3_mon_kn;
+ char name[32];
+
+ sprintf(name, "%s_MON", r->name);
+ l3_mon_kn = kernfs_find_and_get(kn_info, name);
+ if (!l3_mon_kn)
+ return;
+
+ kn_config = kernfs_find_and_get(l3_mon_kn, "mbm_total_bytes_config");
+ if (kn_config) {
+ kernfs_show(kn_config, show);
+ kernfs_put(kn_config);
+ }
+
+ kn_config = kernfs_find_and_get(l3_mon_kn, "mbm_local_bytes_config");
+ if (kn_config) {
+ kernfs_show(kn_config, show);
+ kernfs_put(kn_config);
+ }
+
+ kernfs_put(l3_mon_kn);
+}
+
static int resctrl_mbm_assign_mode_show(struct kernfs_open_file *of,
struct seq_file *s, void *v)
{
@@ -2659,6 +2690,12 @@ static int rdtgroup_mkdir_info_resdir(void *priv, char *name,
ret = resctrl_mkdir_event_configs(r, kn_subdir);
if (ret)
return ret;
+ /*
+ * Hide BMEC related files if mbm_event mode
+ * is enabled.
+ */
+ if (resctrl_arch_mbm_cntr_assign_enabled(r))
+ resctrl_bmec_files_show(r, false);
}
}
--
2.34.1
