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Message-ID: <1966b499476d38cfbed6896dfbc50cddad35a126.1755224735.git.babu.moger@amd.com>
Date: Thu, 14 Aug 2025 21:25:30 -0500
From: Babu Moger <babu.moger@....com>
To: <corbet@....net>, <tony.luck@...el.com>, <reinette.chatre@...el.com>,
<tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
<dave.hansen@...ux.intel.com>
CC: <Dave.Martin@....com>, <james.morse@....com>, <babu.moger@....com>,
<x86@...nel.org>, <hpa@...or.com>, <akpm@...ux-foundation.org>,
<rostedt@...dmis.org>, <paulmck@...nel.org>,
<pawan.kumar.gupta@...ux.intel.com>, <kees@...nel.org>, <arnd@...db.de>,
<fvdl@...gle.com>, <seanjc@...gle.com>, <thomas.lendacky@....com>,
<yosry.ahmed@...ux.dev>, <xin@...or.com>, <sohil.mehta@...el.com>,
<kai.huang@...el.com>, <xiaoyao.li@...el.com>, <peterz@...radead.org>,
<mario.limonciello@....com>, <xin3.li@...el.com>, <perry.yuan@....com>,
<chang.seok.bae@...el.com>, <linux-doc@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <peternewman@...gle.com>,
<eranian@...gle.com>, <gautham.shenoy@....com>
Subject: [PATCH v17 26/33] fs/resctrl: Introduce mbm_assign_on_mkdir to enable assignments on mkdir
The "mbm_event" counter assignment mode allows users to assign a hardware
counter to an RMID, event pair and monitor the bandwidth as long as it is
assigned.
Introduce a user-configurable option that determines if a counter will
automatically be assigned to an RMID, event pair when its associated
monitor group is created via mkdir. Accessible when mbm_event" counter
assignment mode is enabled.
Suggested-by: Peter Newman <peternewman@...gle.com>
Signed-off-by: Babu Moger <babu.moger@....com>
---
v17: Added the check resctrl_arch_mbm_cntr_assign_enabled() in
resctrl_mbm_assign_on_mkdir_show() and resctrl_mbm_assign_on_mkdir_write()
to make it accessible when mbm_event mode is enabled.
Added texts in resctrl.rst about the accessability.
v16: Fixed the return in resctrl_mbm_assign_on_mkdir_write().
v15: Fixed the static checker warning in resctrl_mbm_assign_on_mkdir_write() reported in
https://lore.kernel.org/lkml/dd4a1021-b996-438e-941c-69dfcea5f22a@intel.com/
v14: Added rdtgroup_mutex in resctrl_mbm_assign_on_mkdir_show().
Updated resctrl.rst for clarity.
Fixed squashing of few previous changes.
Added more code documentation.
v13: Added Suggested-by tag.
Resolved conflicts caused by the recent FS/ARCH code restructure.
The rdtgroup.c/monitor.c file has now been split between the FS and ARCH directories.
v12: New patch. Added after the discussion on the list.
https://lore.kernel.org/lkml/CALPaoCh8siZKjL_3yvOYGL4cF_n_38KpUFgHVGbQ86nD+Q2_SA@mail.gmail.com/
---
Documentation/filesystems/resctrl.rst | 20 ++++++++++
fs/resctrl/internal.h | 6 +++
fs/resctrl/monitor.c | 53 +++++++++++++++++++++++++++
fs/resctrl/rdtgroup.c | 7 ++++
include/linux/resctrl.h | 3 ++
5 files changed, 89 insertions(+)
diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
index 2e840ef26f68..1de815b3a07b 100644
--- a/Documentation/filesystems/resctrl.rst
+++ b/Documentation/filesystems/resctrl.rst
@@ -355,6 +355,26 @@ with the following files:
# cat /sys/fs/resctrl/info/L3_MON/event_configs/mbm_total_bytes/event_filter
local_reads,local_non_temporal_writes
+"mbm_assign_on_mkdir":
+ Exists when "mbm_event" counter assignment mode is supported. Accessible
+ only when "mbm_event" counter assignment mode is enabled.
+
+ Determines if a counter will automatically be assigned to an RMID, MBM event
+ pair when its associated monitor group is created via mkdir. Enabled by default
+ on boot, also when switched from "default" mode to "mbm_event" counter assignment
+ mode. Users can disable this capability by writing to the interface.
+
+ "0":
+ Auto assignment is disabled.
+ "1":
+ Auto assignment is enabled.
+
+ Example::
+
+ # echo 0 > /sys/fs/resctrl/info/L3_MON/mbm_assign_on_mkdir
+ # cat /sys/fs/resctrl/info/L3_MON/mbm_assign_on_mkdir
+ 0
+
"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 5956570d49fc..9be1e53a73d3 100644
--- a/fs/resctrl/internal.h
+++ b/fs/resctrl/internal.h
@@ -410,6 +410,12 @@ int event_filter_show(struct kernfs_open_file *of, struct seq_file *seq, void *v
ssize_t event_filter_write(struct kernfs_open_file *of, char *buf, size_t nbytes,
loff_t off);
+int resctrl_mbm_assign_on_mkdir_show(struct kernfs_open_file *of,
+ struct seq_file *s, void *v);
+
+ssize_t resctrl_mbm_assign_on_mkdir_write(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off);
+
#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 9201fedd2796..b3b4d3f44295 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -1148,6 +1148,57 @@ ssize_t event_filter_write(struct kernfs_open_file *of, char *buf, size_t nbytes
return ret ?: nbytes;
}
+int resctrl_mbm_assign_on_mkdir_show(struct kernfs_open_file *of, struct seq_file *s,
+ void *v)
+{
+ struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
+ int ret = 0;
+
+ mutex_lock(&rdtgroup_mutex);
+ rdt_last_cmd_clear();
+
+ if (!resctrl_arch_mbm_cntr_assign_enabled(r)) {
+ rdt_last_cmd_puts("mbm_event counter assignment mode is not enabled\n");
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ seq_printf(s, "%u\n", r->mon.mbm_assign_on_mkdir);
+
+out_unlock:
+ mutex_unlock(&rdtgroup_mutex);
+
+ return ret;
+}
+
+ssize_t resctrl_mbm_assign_on_mkdir_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 value;
+ int ret;
+
+ ret = kstrtobool(buf, &value);
+ if (ret)
+ return ret;
+
+ mutex_lock(&rdtgroup_mutex);
+ rdt_last_cmd_clear();
+
+ if (!resctrl_arch_mbm_cntr_assign_enabled(r)) {
+ rdt_last_cmd_puts("mbm_event counter assignment mode is not enabled\n");
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ r->mon.mbm_assign_on_mkdir = value;
+
+out_unlock:
+ mutex_unlock(&rdtgroup_mutex);
+
+ return ret ?: nbytes;
+}
+
/*
* rdtgroup_assign_cntr() - Assign/unassign the counter ID for the event, RMID
* pair in the domain.
@@ -1464,6 +1515,8 @@ int resctrl_mon_resource_init(void)
resctrl_file_fflags_init("available_mbm_cntrs",
RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
resctrl_file_fflags_init("event_filter", RFTYPE_ASSIGN_CONFIG);
+ resctrl_file_fflags_init("mbm_assign_on_mkdir", RFTYPE_MON_INFO |
+ RFTYPE_RES_CACHE);
}
return 0;
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 8187df7b85d2..ced46eb4a959 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -1808,6 +1808,13 @@ static struct rftype res_common_files[] = {
.seq_show = rdt_last_cmd_status_show,
.fflags = RFTYPE_TOP_INFO,
},
+ {
+ .name = "mbm_assign_on_mkdir",
+ .mode = 0644,
+ .kf_ops = &rdtgroup_kf_single_ops,
+ .seq_show = resctrl_mbm_assign_on_mkdir_show,
+ .write = resctrl_mbm_assign_on_mkdir_write,
+ },
{
.name = "num_closids",
.mode = 0444,
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 04152654827d..a7d92718b653 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -277,12 +277,15 @@ enum resctrl_schema_fmt {
* monitoring events can be configured.
* @num_mbm_cntrs: Number of assignable counters.
* @mbm_cntr_assignable:Is system capable of supporting counter assignment?
+ * @mbm_assign_on_mkdir:True if counters should automatically be assigned to MBM
+ * events of monitor groups created via mkdir.
*/
struct resctrl_mon {
int num_rmid;
unsigned int mbm_cfg_mask;
int num_mbm_cntrs;
bool mbm_cntr_assignable;
+ bool mbm_assign_on_mkdir;
};
/**
--
2.34.1
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