[PATCH RFC v2 13/19] resctrl: Add mbm_assign_scope_mode for native assignment file names
Fenghua Yu
fenghuay at nvidia.com
Mon Aug 31 10:22:39 PDT 2026
On platforms whose MBM counters are backed by NUMA node MSCs,
mbm_NODE_assignments is the native assignment file. User space that
already programs mbm_L3_assignments needs a compatible default.
Add info/MB_MON/mbm_assign_scope_mode. Legacy (default) always exposes
mbm_L3_assignments; that file still programs node-scoped counters when
node MSCs provide MBM. Native mode replaces it with
mbm_NODE_assignments on those platforms.
Signed-off-by: Fenghua Yu <fenghuay at nvidia.com>
---
fs/resctrl/internal.h | 9 +++
fs/resctrl/monitor.c | 147 +++++++++++++++++++++++++++++++++++++---
fs/resctrl/rdtgroup.c | 9 +++
include/linux/resctrl.h | 6 ++
4 files changed, 162 insertions(+), 9 deletions(-)
diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
index 32c7d53790ec..f46d4fb7c624 100644
--- a/fs/resctrl/internal.h
+++ b/fs/resctrl/internal.h
@@ -457,6 +457,15 @@ int mbm_L3_assignments_show(struct kernfs_open_file *of, struct seq_file *s, voi
ssize_t mbm_L3_assignments_write(struct kernfs_open_file *of, char *buf, size_t nbytes,
loff_t off);
+
+int resctrl_mbm_assign_scope_mode_show(struct kernfs_open_file *of, struct seq_file *s,
+ void *v);
+
+ssize_t resctrl_mbm_assign_scope_mode_write(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off);
+
+void resctrl_mbm_assign_files_apply(struct kernfs_node *kn);
+
int resctrl_io_alloc_show(struct kernfs_open_file *of, struct seq_file *seq, void *v);
int rdtgroup_init_cat(struct rdt_resource_final *f, struct resctrl_ctrl *ctrl,
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index d555f2d19164..074dc2a040dc 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -18,6 +18,7 @@
#define pr_fmt(fmt) "resctrl: " fmt
#include <linux/cpu.h>
+#include <linux/kernfs.h>
#include <linux/resctrl.h>
#include <linux/sizes.h>
#include <linux/slab.h>
@@ -1704,6 +1705,130 @@ int resctrl_available_mbm_cntrs_show(struct kernfs_open_file *of,
return ret;
}
+static bool resctrl_mbm_has_node_mscs(void)
+{
+ struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_MBA);
+
+ return r->mon_capable && r->mon_scope == RESCTRL_NODE;
+}
+
+static bool resctrl_mbm_show_l3_assignments(void)
+{
+ return !resctrl_arch_get_resource(RDT_RESOURCE_MBA)->mon.mbm_assign_scope_native ||
+ !resctrl_mbm_has_node_mscs();
+}
+
+static bool resctrl_mbm_show_node_assignments(void)
+{
+ return resctrl_arch_get_resource(RDT_RESOURCE_MBA)->mon.mbm_assign_scope_native &&
+ resctrl_mbm_has_node_mscs();
+}
+
+static struct rdt_resource *mbm_l3_assignments_resource(void)
+{
+ if (resctrl_mbm_has_node_mscs())
+ return resctrl_arch_get_resource(RDT_RESOURCE_MBA);
+
+ return resctrl_arch_get_resource(RDT_RESOURCE_L3);
+}
+
+static void resctrl_mbm_assign_file_show(struct kernfs_node *parent, const char *name,
+ bool show)
+{
+ struct kernfs_node *kn;
+
+ kn = kernfs_find_and_get(parent, name);
+ if (!kn)
+ return;
+
+ kernfs_show(kn, show);
+ kernfs_put(kn);
+}
+
+void resctrl_mbm_assign_files_apply(struct kernfs_node *kn)
+{
+ if (!kn)
+ return;
+
+ resctrl_mbm_assign_file_show(kn, "mbm_L3_assignments",
+ resctrl_mbm_show_l3_assignments());
+ resctrl_mbm_assign_file_show(kn, "mbm_NODE_assignments",
+ resctrl_mbm_show_node_assignments());
+}
+
+static void resctrl_mbm_assign_files_apply_all(void)
+{
+ struct rdtgroup *prgrp, *crgrp;
+
+ lockdep_assert_held(&rdtgroup_mutex);
+
+ list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
+ resctrl_mbm_assign_files_apply(prgrp->kn);
+ list_for_each_entry(crgrp, &prgrp->mon.crdtgrp_list, mon.crdtgrp_list)
+ resctrl_mbm_assign_files_apply(crgrp->kn);
+ }
+}
+
+int resctrl_mbm_assign_scope_mode_show(struct kernfs_open_file *of,
+ struct seq_file *s, void *v)
+{
+ struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
+
+ if (!info_kn_lock(of->kn))
+ return -ENOENT;
+
+ if (r->mon.mbm_assign_scope_native)
+ seq_puts(s, "legacy [native]\n");
+ else
+ seq_puts(s, "[legacy] native\n");
+
+ info_kn_unlock(of->kn);
+
+ return 0;
+}
+
+ssize_t resctrl_mbm_assign_scope_mode_write(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
+{
+ struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
+ bool native;
+ int ret = 0;
+
+ if (!info_kn_lock(of->kn))
+ return -ENOENT;
+
+ rdt_last_cmd_clear();
+
+ /* Valid input requires a trailing newline */
+ if (nbytes == 0 || buf[nbytes - 1] != '\n') {
+ rdt_last_cmd_puts("mbm_assign_scope_mode: Invalid input\n");
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ buf[nbytes - 1] = '\0';
+
+ if (!strcmp(buf, "legacy")) {
+ native = false;
+ } else if (!strcmp(buf, "native")) {
+ native = true;
+ } else {
+ rdt_last_cmd_puts("Unsupported assign scope mode\n");
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ if (r->mon.mbm_assign_scope_native != native) {
+ r->mon.mbm_assign_scope_native = native;
+ resctrl_mbm_assign_files_apply_all();
+ }
+
+out_unlock:
+ info_kn_unlock(of->kn);
+
+ return ret ?: nbytes;
+}
+
static int mbm_assignments_show(struct kernfs_open_file *of, struct seq_file *s,
void *v, struct rdt_resource *r)
{
@@ -1753,8 +1878,7 @@ static int mbm_assignments_show(struct kernfs_open_file *of, struct seq_file *s,
int mbm_L3_assignments_show(struct kernfs_open_file *of, struct seq_file *s, void *v)
{
- return mbm_assignments_show(of, s, v,
- resctrl_arch_get_resource(RDT_RESOURCE_L3));
+ return mbm_assignments_show(of, s, v, mbm_l3_assignments_resource());
}
int mbm_NODE_assignments_show(struct kernfs_open_file *of, struct seq_file *s, void *v)
@@ -1873,7 +1997,7 @@ static ssize_t mbm_assignments_write(struct kernfs_open_file *of, char *buf,
/* Valid input requires a trailing newline */
if (nbytes == 0 || buf[nbytes - 1] != '\n') {
- rdt_last_cmd_puts("mbm_L3_assignments: Invalid input\n");
+ rdt_last_cmd_puts("mbm assignments: Invalid input\n");
ret = -EINVAL;
goto out_unlock;
}
@@ -1909,14 +2033,14 @@ ssize_t mbm_L3_assignments_write(struct kernfs_open_file *of, char *buf,
size_t nbytes, loff_t off)
{
return mbm_assignments_write(of, buf, nbytes, off,
- resctrl_arch_get_resource(RDT_RESOURCE_L3));
+ mbm_l3_assignments_resource());
}
ssize_t mbm_NODE_assignments_write(struct kernfs_open_file *of, char *buf,
size_t nbytes, loff_t off)
{
return mbm_assignments_write(of, buf, nbytes, off,
- resctrl_arch_get_resource(RDT_RESOURCE_MBA));
+ resctrl_arch_get_resource(RDT_RESOURCE_MBA));
}
static int closid_num_dirty_rmid_alloc(struct rdt_resource *r)
@@ -2012,10 +2136,15 @@ static void resctrl_mon_resource_init(struct rdt_resource *r)
resctrl_file_mode_init("event_filter", 0644);
resctrl_file_fflags_init("mbm_assign_on_mkdir", RFTYPE_MON_INFO |
fflags);
- if (r->rid == RDT_RESOURCE_MBA)
- resctrl_file_fflags_init("mbm_NODE_assignments", RFTYPE_MON_BASE);
- else
- resctrl_file_fflags_init("mbm_L3_assignments", RFTYPE_MON_BASE);
+ resctrl_file_fflags_init("mbm_L3_assignments", RFTYPE_MON_BASE);
+ if (r->rid == RDT_RESOURCE_MBA) {
+ r->mon.mbm_assign_scope_native = false;
+ resctrl_file_fflags_init("mbm_assign_scope_mode",
+ RFTYPE_MON_INFO | RFTYPE_RES_MB);
+ if (r->mon_scope == RESCTRL_NODE)
+ resctrl_file_fflags_init("mbm_NODE_assignments",
+ RFTYPE_MON_BASE);
+ }
resctrl_file_fflags_init("mbm_assign_mode", RFTYPE_MON_INFO |
fflags);
}
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index a16e35b587c4..1547306dc8d6 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -2316,6 +2316,13 @@ static struct rftype res_common_files[] = {
.seq_show = mbm_NODE_assignments_show,
.write = mbm_NODE_assignments_write,
},
+ {
+ .name = "mbm_assign_scope_mode",
+ .mode = 0644,
+ .kf_ops = &rdtgroup_kf_single_ops,
+ .seq_show = resctrl_mbm_assign_scope_mode_show,
+ .write = resctrl_mbm_assign_scope_mode_write,
+ },
{
.name = "mbm_assign_mode",
.mode = 0644,
@@ -2653,6 +2660,8 @@ static int rdtgroup_add_files(struct kernfs_node *kn, unsigned long fflags)
}
}
+ resctrl_mbm_assign_files_apply(kn);
+
return 0;
error:
pr_warn("Failed to add %s, err=%d\n", rft->name, ret);
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index b8df7489539f..141e2ff594f9 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -380,6 +380,11 @@ enum resctrl_ctrl_type {
* events of monitor groups created via mkdir.
* @mbm_cntr_configurable: True if assignable counters are configurable.
* @mbm_cntr_assign_fixed: True if the counter assignment mode is fixed.
+ * @mbm_assign_scope_native: True if assignment files use native names.
+ * Legacy mode always exposes "mbm_L3_assignments".
+ * Native mode exposes "mbm_NODE_assignments" when
+ * NUMA node MSCs are present, otherwise
+ * "mbm_L3_assignments".
*/
struct resctrl_mon {
u32 num_rmid;
@@ -389,6 +394,7 @@ struct resctrl_mon {
bool mbm_assign_on_mkdir;
bool mbm_cntr_configurable;
bool mbm_cntr_assign_fixed;
+ bool mbm_assign_scope_native;
};
/**
--
2.53.0
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