Introduce interface to switch between ABMC and legacy modes.
By default ABMC is enabled on boot if the feature is available.
Provide the interface to go back to legacy mode if required.
$ cat /sys/fs/resctrl/info/L3_MON/mbm_mode
[mbm_cntr_assign]
legacy
To enable the "mbm_cntr_assign" mode:
$ echo "mbm_cntr_assign" > /sys/fs/resctrl/info/L3_MON/mbm_mode
To enable the legacy monitoring feature:
$ echo "legacy" > /sys/fs/resctrl/info/L3_MON/mbm_mode
MBM event counters will reset when mbm_mode is changed.
Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
---
v6: Changed the mode name to mbm_cntr_assign.
Moved all the FS related code here.
Added changes to reset mbm_cntr_map and resctrl group counters.
v5: Change log and mode description text correction.
v4: Minor commit text changes. Keep the default to ABMC when supported.
Fixed comments to reflect changed interface "mbm_mode".
v3: New patch to address the review comments from upstream.
---
Documentation/arch/x86/resctrl.rst | 15 +++++++
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 62 +++++++++++++++++++++++++-
2 files changed, 76 insertions(+), 1 deletion(-)
diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index aea440ee6107..d6d6a8276401 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -291,6 +291,21 @@ with the following files:
as long as there are enough RMID counters available to support number
of monitoring groups.
+ * To enable ABMC feature:
+ ::
+
+ # echo "mbm_cntr_assign" > /sys/fs/resctrl/info/L3_MON/mbm_mode
+
+ * To enable the legacy monitoring feature:
+ ::
+
+ # echo "legacy" > /sys/fs/resctrl/info/L3_MON/mbm_mode
+
+ The MBM event counters will reset when mbm_mode is changed. Moving to
+ mbm_cntr_assign will require users to assign the counters to the events to
+ read the events. Otherwise, the MBM event counters will return "Unassigned"
+ when read.
+
"num_mbm_cntrs":
The number of monitoring counters available for assignment.
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index d93c1d784b91..66febff2a3d3 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -896,6 +896,65 @@ static int rdtgroup_mbm_mode_show(struct kernfs_open_file *of,
return 0;
}
+static void rdtgroup_mbm_cntr_reset(struct rdt_resource *r)
+{
+ struct rdtgroup *prgrp, *crgrp;
+ struct rdt_mon_domain *dom;
+
+ mbm_cntrs_init(r);
+
+ list_for_each_entry(dom, &r->mon_domains, hdr.list)
+ bitmap_zero(dom->mbm_cntr_map, r->mon.num_mbm_cntrs);
+
+ /* Reset the cntr_id's for all the monitor groups */
+ list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
+ prgrp->mon.cntr_id[0] = MON_CNTR_UNSET;
+ prgrp->mon.cntr_id[1] = MON_CNTR_UNSET;
+ list_for_each_entry(crgrp, &prgrp->mon.crdtgrp_list,
+ mon.crdtgrp_list) {
+ crgrp->mon.cntr_id[0] = MON_CNTR_UNSET;
+ crgrp->mon.cntr_id[1] = MON_CNTR_UNSET;
+ }
+ }
+}
+
+static ssize_t rdtgroup_mbm_mode_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes,
+ loff_t off)
+{
+ int mbm_cntr_assign = resctrl_arch_get_abmc_enabled();
+ struct rdt_resource *r = of->kn->parent->priv;
+ int ret = 0;
+
+ /* Valid input requires a trailing newline */
+ if (nbytes == 0 || buf[nbytes - 1] != '\n')
+ return -EINVAL;
+
+ buf[nbytes - 1] = '\0';
+
+ cpus_read_lock();
+ mutex_lock(&rdtgroup_mutex);
+
+ rdt_last_cmd_clear();
+
+ if (!strcmp(buf, "legacy")) {
+ if (mbm_cntr_assign)
+ resctrl_arch_mbm_cntr_assign_disable();
+ } else if (!strcmp(buf, "mbm_cntr_assign")) {
+ if (!mbm_cntr_assign) {
+ rdtgroup_mbm_cntr_reset(r);
+ ret = resctrl_arch_mbm_cntr_assign_enable();
+ }
+ } else {
+ ret = -EINVAL;
+ }
+
+ mutex_unlock(&rdtgroup_mutex);
+ cpus_read_unlock();
+
+ return ret ?: nbytes;
+}
+
static int rdtgroup_num_mbm_cntrs_show(struct kernfs_open_file *of,
struct seq_file *s, void *v)
{
@@ -2127,9 +2186,10 @@ static struct rftype res_common_files[] = {
},
{
.name = "mbm_mode",
- .mode = 0444,
+ .mode = 0644,
.kf_ops = &rdtgroup_kf_single_ops,
.seq_show = rdtgroup_mbm_mode_show,
+ .write = rdtgroup_mbm_mode_write,
.fflags = RFTYPE_MON_INFO,
},
{
--
2.34.1
