Resctrl subsystem can support two monitoring modes, "mbm_cntr_assign" or
"default". In mbm_cntr_assign, monitoring event can only accumulate data
while it is backed by a hardware counter. In "default" mode, resctrl
assumes there is a hardware counter for each event within every CTRL_MON
and MON group.
Introduce interface to switch between mbm_cntr_assign and default modes.
$ cat /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
[mbm_cntr_assign]
default
To enable the "mbm_cntr_assign" monitoring mode:
$ echo "mbm_cntr_assign" > /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
To enable the "default" monitoring mode:
$ echo "default" > /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
MBM event counters are automatically reset as part of changing the mode.
Clear both architectural and non-architectural event states to prevent
overflow conditions during the next event read.
Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
---
v13: Resolved the conflicts due to FS/ARCH restructure.
Introduced the new resctrl_init_evt_configuration() to initialize
the event modes and configuration values.
Added the call to resctrl_bmec_files_show() hide/show BMEC related
files.
v12: Fixed the documentation for a consistency.
Introduced mbm_cntr_free_all() and resctrl_reset_rmid_all() to clear
counters and non-architectural states when monitor mode is changed.
https://lore.kernel.org/lkml/b60b4f72-6245-46db-a126-428fb13b6310@xxxxxxxxx/
v11: Changed the name of the function rdtgroup_mbm_assign_mode_write() to
resctrl_mbm_assign_mode_write().
Rewrote the commit message with context.
Added few more details in resctrl.rst about mbm_cntr_assign mode.
Re-arranged the text in resctrl.rst file.
v10: The call mbm_cntr_reset() has been moved to earlier patch.
Minor documentation update.
v9: Fixed extra spaces in user documentation.
Fixed problem changing the mode to mbm_cntr_assign mode when it is
not supported. Added extra checks to detect if systems supports it.
Used the rdtgroup_cntr_id_init to initialize cntr_id.
v8: Reset the internal counters after mbm_cntr_assign mode is changed.
Renamed rdtgroup_mbm_cntr_reset() to mbm_cntr_reset()
Updated the documentation to make text generic.
v7: Changed the interface name to mbm_assign_mode.
Removed the references of ABMC.
Added the changes to reset global and domain bitmaps.
Added the changes to reset rmid.
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/filesystems/resctrl.rst | 25 ++++++++++-
fs/resctrl/internal.h | 3 ++
fs/resctrl/monitor.c | 53 +++++++++++++++++++---
fs/resctrl/rdtgroup.c | 65 ++++++++++++++++++++++++++-
4 files changed, 138 insertions(+), 8 deletions(-)
diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
index d779554a2f91..7c304821ce93 100644
--- a/Documentation/filesystems/resctrl.rst
+++ b/Documentation/filesystems/resctrl.rst
@@ -259,7 +259,10 @@ with the following files:
"mbm_assign_mode":
Reports the list of monitoring modes supported. The enclosed brackets
- indicate which mode is enabled.
+ indicate which mode is enabled. The MBM events (mbm_total_bytes and/or
+ mbm_local_bytes) associated with counters may reset when "mbm_assign_mode"
+ is changed.
+
::
# cat /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
@@ -275,6 +278,16 @@ with the following files:
"num_mbm_cntrs" file. Changing the mode may cause all counters on the
resource to reset.
+ Moving to mbm_cntr_assign mode require users to assign the counters to
+ the events. Otherwise, the MBM event counters will return 'Unassigned'
+ when read.
+
+ The mode is beneficial for AMD platforms that support more CTRL_MON
+ and MON groups than available hardware counters. By default, this
+ feature is enabled on AMD platforms with the ABMC (Assignable Bandwidth
+ Monitoring Counters) capability, ensuring counters remain assigned even
+ when the corresponding RMID is not actively used by any processor.
+
"default":
In default mode, resctrl assumes there is a hardware counter for each
@@ -284,6 +297,16 @@ with the following files:
counters. This can result in misleading values or display "Unavailable"
if no counter is assigned to the event.
+ * To enable "mbm_cntr_assign" monitoring mode:
+ ::
+
+ # echo "mbm_cntr_assign" > /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
+
+ * To enable "default" monitoring mode:
+ ::
+
+ # echo "default" > /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
+
"num_mbm_cntrs":
The maximum number of monitoring counters (total of available and assigned
counters) in each domain when the system supports mbm_cntr_assign mode.
diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
index a6069a5dfd49..d5edb28a8df7 100644
--- a/fs/resctrl/internal.h
+++ b/fs/resctrl/internal.h
@@ -404,6 +404,9 @@ int resctrl_unassign_cntr_event(struct rdt_resource *r, struct rdt_mon_domain *d
struct rdtgroup *rdtgrp, enum resctrl_event_id evtid);
int mbm_cntr_get(struct rdt_resource *r, struct rdt_mon_domain *d,
struct rdtgroup *rdtgrp, enum resctrl_event_id evtid);
+void resctrl_reset_rmid_all(struct rdt_resource *r, struct rdt_mon_domain *d);
+void mbm_cntr_free_all(struct rdt_resource *r, struct rdt_mon_domain *d);
+void resctrl_init_evt_configuration(struct rdt_resource *r, bool enable);
#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 b982540ce4e3..bebe83cf48d5 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -911,16 +911,13 @@ int resctrl_mon_resource_init(void)
l3_mon_evt_init(r);
- if (resctrl_arch_is_evt_configurable(QOS_L3_MBM_TOTAL_EVENT_ID)) {
- mbm_total_event.mbm_mode = MBM_MODE_BMEC;
+ if (resctrl_arch_is_evt_configurable(QOS_L3_MBM_TOTAL_EVENT_ID))
resctrl_file_fflags_init("mbm_total_bytes_config",
RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
- }
- if (resctrl_arch_is_evt_configurable(QOS_L3_MBM_LOCAL_EVENT_ID)) {
- mbm_local_event.mbm_mode = MBM_MODE_BMEC;
+
+ if (resctrl_arch_is_evt_configurable(QOS_L3_MBM_LOCAL_EVENT_ID))
resctrl_file_fflags_init("mbm_local_bytes_config",
RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
- }
if (resctrl_arch_is_mbm_local_enabled())
mba_mbps_default_event = QOS_L3_MBM_LOCAL_EVENT_ID;
@@ -938,6 +935,8 @@ int resctrl_mon_resource_init(void)
resctrl_file_fflags_init("mbm_L3_assignments", RFTYPE_MON_BASE);
}
+ resctrl_init_evt_configuration(r, true);
+
return 0;
}
@@ -1010,6 +1009,25 @@ static void mbm_cntr_free(struct rdt_mon_domain *d, int cntr_id)
memset(&d->cntr_cfg[cntr_id], 0, sizeof(struct mbm_cntr_cfg));
}
+void mbm_cntr_free_all(struct rdt_resource *r, struct rdt_mon_domain *d)
+{
+ memset(d->cntr_cfg, 0, sizeof(*d->cntr_cfg) * r->mon.num_mbm_cntrs);
+}
+
+/*
+ * Reset all non-architecture states for all the supported RMIDs.
+ */
+void resctrl_reset_rmid_all(struct rdt_resource *r, struct rdt_mon_domain *d)
+{
+ u32 idx_limit = resctrl_arch_system_num_rmid_idx();
+
+ if (resctrl_arch_is_mbm_total_enabled())
+ memset(d->mbm_total, 0, sizeof(struct mbm_state) * idx_limit);
+
+ if (resctrl_arch_is_mbm_local_enabled())
+ memset(d->mbm_local, 0, sizeof(struct mbm_state) * idx_limit);
+}
+
/*
* mbm_get_mon_event() - Return the mon_evt entry for the matching evtid.
*/
@@ -1119,6 +1137,29 @@ static int resctrl_free_config_cntr(struct rdt_resource *r, struct rdt_mon_domai
return 0;
}
+/*
+ * Initialize the event modes and configuration values.
+ *
+ * total event is set to count all the supported memory transactions.
+ * local event is set to count all the local memory transactions.
+ */
+void resctrl_init_evt_configuration(struct rdt_resource *r, bool enable)
+{
+ if (resctrl_arch_mbm_cntr_assign_enabled(r)) {
+ mbm_total_event.mbm_mode = MBM_MODE_ASSIGN;
+ mbm_total_event.evt_cfg = MAX_EVT_CONFIG_BITS;
+ mbm_local_event.mbm_mode = MBM_MODE_ASSIGN;
+ mbm_local_event.evt_cfg = READS_TO_LOCAL_MEM |
+ NON_TEMP_WRITE_TO_LOCAL_MEM |
+ READS_TO_LOCAL_S_MEM;
+ } else {
+ if (resctrl_arch_is_evt_configurable(QOS_L3_MBM_TOTAL_EVENT_ID))
+ mbm_total_event.mbm_mode = MBM_MODE_BMEC;
+ if (resctrl_arch_is_evt_configurable(QOS_L3_MBM_LOCAL_EVENT_ID))
+ mbm_local_event.mbm_mode = MBM_MODE_BMEC;
+ }
+}
+
/*
* Unassign a hardware counter associated with @evtid from the domain and
* the group. Unassign the counters from all the domains if @d is NULL else
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index d6bf2a50a105..c76d598e4d23 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -1872,6 +1872,68 @@ static int resctrl_mbm_assign_mode_show(struct kernfs_open_file *of,
return 0;
}
+static ssize_t resctrl_mbm_assign_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);
+ struct rdt_mon_domain *d;
+ int ret = 0;
+ bool enable;
+
+ /* 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, "default")) {
+ enable = 0;
+ } else if (!strcmp(buf, "mbm_cntr_assign")) {
+ if (r->mon.mbm_cntr_assignable) {
+ enable = 1;
+ } else {
+ ret = -EINVAL;
+ rdt_last_cmd_puts("mbm_cntr_assign mode is not supported\n");
+ goto write_exit;
+ }
+ } else {
+ ret = -EINVAL;
+ rdt_last_cmd_puts("Unsupported assign mode\n");
+ goto write_exit;
+ }
+
+ if (enable != resctrl_arch_mbm_cntr_assign_enabled(r)) {
+ ret = resctrl_arch_mbm_cntr_assign_set(r, enable);
+ if (ret)
+ goto write_exit;
+
+ /* Initialize event configuration details accordingly */
+ resctrl_init_evt_configuration(r, enable);
+
+ /* Update the visibility of BMEC related files */
+ resctrl_bmec_files_show(r, !enable);
+
+ /*
+ * Reset all the non-achitectural RMID state and assignable counters.
+ */
+ list_for_each_entry(d, &r->mon_domains, hdr.list) {
+ mbm_cntr_free_all(r, d);
+ resctrl_reset_rmid_all(r, d);
+ }
+ }
+
+write_exit:
+ mutex_unlock(&rdtgroup_mutex);
+ cpus_read_unlock();
+
+ return ret ?: nbytes;
+}
+
static int resctrl_num_mbm_cntrs_show(struct kernfs_open_file *of,
struct seq_file *s, void *v)
{
@@ -2462,9 +2524,10 @@ static struct rftype res_common_files[] = {
},
{
.name = "mbm_assign_mode",
- .mode = 0444,
+ .mode = 0644,
.kf_ops = &rdtgroup_kf_single_ops,
.seq_show = resctrl_mbm_assign_mode_show,
+ .write = resctrl_mbm_assign_mode_write,
.fflags = RFTYPE_MON_INFO | RFTYPE_RES_CACHE,
},
{
--
2.34.1
