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Message-ID: <bfab743a93ed88a841afd5b1a6398accd8d1d32a.1747349530.git.babu.moger@amd.com>
Date: Thu, 15 May 2025 17:51:52 -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: <james.morse@....com>, <dave.martin@....com>, <fenghuay@...dia.com>,
<x86@...nel.org>, <hpa@...or.com>, <paulmck@...nel.org>,
<akpm@...ux-foundation.org>, <thuth@...hat.com>, <rostedt@...dmis.org>,
<ardb@...nel.org>, <gregkh@...uxfoundation.org>,
<daniel.sneddon@...ux.intel.com>, <jpoimboe@...nel.org>,
<alexandre.chartre@...cle.com>, <pawan.kumar.gupta@...ux.intel.com>,
<thomas.lendacky@....com>, <perry.yuan@....com>, <seanjc@...gle.com>,
<kai.huang@...el.com>, <xiaoyao.li@...el.com>, <babu.moger@....com>,
<kan.liang@...ux.intel.com>, <xin3.li@...el.com>, <ebiggers@...gle.com>,
<xin@...or.com>, <sohil.mehta@...el.com>, <andrew.cooper3@...rix.com>,
<mario.limonciello@....com>, <linux-doc@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <peternewman@...gle.com>,
<maciej.wieczor-retman@...el.com>, <eranian@...gle.com>,
<Xiaojian.Du@....com>, <gautham.shenoy@....com>
Subject: [PATCH v13 07/27] x86/resctrl: Introduce interface to display number of monitoring counters
The mbm_cntr_assign mode provides an option to the user to assign a counter
to an RMID, event pair and monitor the bandwidth as long as the counter is
assigned. Number of assignments depend on number of monitoring counters
available.
Create 'num_mbm_cntrs' resctrl file that displays the number of monitoring
counters supported in each domain. 'num_mbm_cntrs' is only visible to user
space when the system supports mbm_cntr_assign mode.
Signed-off-by: Babu Moger <babu.moger@....com>
---
v13: Updated the changelog.
Added fflags RFTYPE_RES_CACHE to the file num_mbm_cntrs.
Replaced seq_puts from seq_putc where applicable.
Resolved conflicts caused by the recent FS/ARCH code restructure.
The files monitor.c/rdtgroup.c have been split between FS and ARCH directories.
v12: Changed the code to display the max supported monitoring counters in
each domain. Also updated the documentation.
Resolved the conflict with the latest code.
v11: Renamed rdtgroup_num_mbm_cntrs_show() to resctrl_num_mbm_cntrs_show().
Few monor text updates.
v10: No changes.
v9: Updated user document based on the comments.
Will add a new file available_mbm_cntrs later in the series.
v8: Commit message update and documentation update.
v7: Minor commit log text changes.
v6: No changes.
v5: Changed the display name from num_cntrs to num_mbm_cntrs.
Updated the commit message.
Moved the patch after mbm_mode is introduced.
v4: Changed the counter name to num_cntrs. And few text changes.
v3: Changed the field name to mbm_assign_cntrs.
v2: Changed the field name to mbm_assignable_counters from abmc_counter.
---
Documentation/filesystems/resctrl.rst | 11 ++++++++++
fs/resctrl/monitor.c | 4 ++++
fs/resctrl/rdtgroup.c | 30 +++++++++++++++++++++++++++
3 files changed, 45 insertions(+)
diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
index 8013418b6ca2..abbbbdf61062 100644
--- a/Documentation/filesystems/resctrl.rst
+++ b/Documentation/filesystems/resctrl.rst
@@ -284,6 +284,17 @@ with the following files:
counters. This can result in misleading values or display "Unavailable"
if no counter is assigned to the event.
+"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.
+
+ For example, on a system with maximum of 32 memory bandwidth monitoring
+ counters in each of its L3 domains:
+ ::
+
+ # cat /sys/fs/resctrl/info/L3_MON/num_mbm_cntrs
+ 0=32;1=32
+
"max_threshold_occupancy":
Read/write file provides the largest value (in
bytes) at which a previously used LLC_occupancy
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index 6ffa9d14a8b4..039516cf410d 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -918,6 +918,10 @@ int resctrl_mon_resource_init(void)
else if (resctrl_arch_is_mbm_total_enabled())
mba_mbps_default_event = QOS_L3_MBM_TOTAL_EVENT_ID;
+ if (r->mon.mbm_cntr_assignable)
+ resctrl_file_fflags_init("num_mbm_cntrs",
+ RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
+
return 0;
}
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index a9e1055df75f..51f8f8d3ccbc 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -1831,6 +1831,30 @@ static int resctrl_mbm_assign_mode_show(struct kernfs_open_file *of,
return 0;
}
+static int resctrl_num_mbm_cntrs_show(struct kernfs_open_file *of,
+ struct seq_file *s, void *v)
+{
+ struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
+ struct rdt_mon_domain *dom;
+ bool sep = false;
+
+ cpus_read_lock();
+ mutex_lock(&rdtgroup_mutex);
+
+ list_for_each_entry(dom, &r->mon_domains, hdr.list) {
+ if (sep)
+ seq_putc(s, ';');
+
+ seq_printf(s, "%d=%d", dom->hdr.id, r->mon.num_mbm_cntrs);
+ sep = true;
+ }
+ seq_putc(s, '\n');
+
+ mutex_unlock(&rdtgroup_mutex);
+ cpus_read_unlock();
+ return 0;
+}
+
/* rdtgroup information files for one cache resource. */
static struct rftype res_common_files[] = {
{
@@ -1868,6 +1892,12 @@ static struct rftype res_common_files[] = {
.seq_show = rdt_default_ctrl_show,
.fflags = RFTYPE_CTRL_INFO | RFTYPE_RES_CACHE,
},
+ {
+ .name = "num_mbm_cntrs",
+ .mode = 0444,
+ .kf_ops = &rdtgroup_kf_single_ops,
+ .seq_show = resctrl_num_mbm_cntrs_show,
+ },
{
.name = "min_cbm_bits",
.mode = 0444,
--
2.34.1
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