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Message-ID: <20250912221053.11349-11-tony.luck@intel.com>
Date: Fri, 12 Sep 2025 15:10:31 -0700
From: Tony Luck <tony.luck@...el.com>
To: Fenghua Yu <fenghuay@...dia.com>,
Reinette Chatre <reinette.chatre@...el.com>,
Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>,
Peter Newman <peternewman@...gle.com>,
James Morse <james.morse@....com>,
Babu Moger <babu.moger@....com>,
Drew Fustini <dfustini@...libre.com>,
Dave Martin <Dave.Martin@....com>,
Chen Yu <yu.c.chen@...el.com>
Cc: x86@...nel.org,
linux-kernel@...r.kernel.org,
patches@...ts.linux.dev,
Tony Luck <tony.luck@...el.com>
Subject: [PATCH v10 10/28] x86,fs/resctrl: Handle events that can be read from any CPU
resctrl assumes that monitor events can only be read from a CPU in the
cpumask_t set of each domain.
This is true for x86 events accessed with an MSR interface, but may
not be true for other access methods such as MMIO.
Add a flag to struct mon_evt to indicate if the event can be read on
any CPU.
Architecture uses resctrl_enable_mon_event() to enable an event and
set the flag appropriately.
Bypass all the smp_call*() code for events that can be read on any CPU
and call mon_event_count() directly from mon_event_read().
Add a test for events that can be read from any domain to skip checks
in __mon_event_count() that the read is being done from a CPU in the
correct domain or cache scope.
Signed-off-by: Tony Luck <tony.luck@...el.com>
---
include/linux/resctrl.h | 2 +-
fs/resctrl/internal.h | 2 ++
arch/x86/kernel/cpu/resctrl/core.c | 6 +++---
fs/resctrl/ctrlmondata.c | 6 ++++++
fs/resctrl/monitor.c | 13 ++++++++++---
5 files changed, 22 insertions(+), 7 deletions(-)
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 66569662efee..22edd8d131d8 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -409,7 +409,7 @@ u32 resctrl_arch_get_num_closid(struct rdt_resource *r);
u32 resctrl_arch_system_num_rmid_idx(void);
int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid);
-void resctrl_enable_mon_event(enum resctrl_event_id eventid);
+void resctrl_enable_mon_event(enum resctrl_event_id eventid, bool any_cpu);
bool resctrl_is_mon_event_enabled(enum resctrl_event_id eventid);
diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
index b6578e572f60..45b97835449f 100644
--- a/fs/resctrl/internal.h
+++ b/fs/resctrl/internal.h
@@ -61,6 +61,7 @@ static inline struct rdt_fs_context *rdt_fc2context(struct fs_context *fc)
* READS_TO_REMOTE_MEM) being tracked by @evtid.
* Only valid if @evtid is an MBM event.
* @configurable: true if the event is configurable
+ * @any_cpu: true if the event can be read from any CPU
* @enabled: true if the event is enabled
*/
struct mon_evt {
@@ -69,6 +70,7 @@ struct mon_evt {
char *name;
u32 evt_cfg;
bool configurable;
+ bool any_cpu;
bool enabled;
};
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 6608d1097eae..040962751250 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -892,15 +892,15 @@ static __init bool get_rdt_mon_resources(void)
bool ret = false;
if (rdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC)) {
- resctrl_enable_mon_event(QOS_L3_OCCUP_EVENT_ID);
+ resctrl_enable_mon_event(QOS_L3_OCCUP_EVENT_ID, false);
ret = true;
}
if (rdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL)) {
- resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID);
+ resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID, false);
ret = true;
}
if (rdt_cpu_has(X86_FEATURE_CQM_MBM_LOCAL)) {
- resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID);
+ resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID, false);
ret = true;
}
if (rdt_cpu_has(X86_FEATURE_ABMC))
diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c
index 77602563cb1f..fbf55e61445c 100644
--- a/fs/resctrl/ctrlmondata.c
+++ b/fs/resctrl/ctrlmondata.c
@@ -574,6 +574,11 @@ void mon_event_read(struct rmid_read *rr, struct rdt_resource *r,
}
}
+ if (evt->any_cpu) {
+ mon_event_count(rr);
+ goto out_ctx_free;
+ }
+
cpu = cpumask_any_housekeeping(cpumask, RESCTRL_PICK_ANY_CPU);
/*
@@ -587,6 +592,7 @@ void mon_event_read(struct rmid_read *rr, struct rdt_resource *r,
else
smp_call_on_cpu(cpu, smp_mon_event_count, rr, false);
+out_ctx_free:
if (rr->arch_mon_ctx)
resctrl_arch_mon_ctx_free(r, evt->evtid, rr->arch_mon_ctx);
}
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index 276041c1a922..9cdda6ff2e14 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -414,6 +414,8 @@ static void mbm_cntr_free(struct rdt_l3_mon_domain *d, int cntr_id)
}
/*
+ * Called from preemptible context via a direct call of mon_event_count() for
+ * events that can be read on any CPU.
* Called from preemptible but non-migratable process context (mon_event_count()
* via smp_call_on_cpu()) OR non-preemptible context (mon_event_count() via
* smp_call_function_any()) for events that need to be read on a specific CPU.
@@ -422,6 +424,10 @@ static bool cpu_on_correct_domain(struct rmid_read *rr)
{
int cpu;
+ /* Any CPU is OK for this event */
+ if (rr->evt->any_cpu)
+ return true;
+
cpu = smp_processor_id();
/* Single domain. Must be on a CPU in that domain. */
@@ -975,7 +981,7 @@ struct mon_evt mon_event_all[QOS_NUM_EVENTS] = {
},
};
-void resctrl_enable_mon_event(enum resctrl_event_id eventid)
+void resctrl_enable_mon_event(enum resctrl_event_id eventid, bool any_cpu)
{
if (WARN_ON_ONCE(eventid < QOS_FIRST_EVENT || eventid >= QOS_NUM_EVENTS))
return;
@@ -984,6 +990,7 @@ void resctrl_enable_mon_event(enum resctrl_event_id eventid)
return;
}
+ mon_event_all[eventid].any_cpu = any_cpu;
mon_event_all[eventid].enabled = true;
}
@@ -1809,9 +1816,9 @@ int resctrl_l3_mon_resource_init(void)
if (r->mon.mbm_cntr_assignable) {
if (!resctrl_is_mon_event_enabled(QOS_L3_MBM_TOTAL_EVENT_ID))
- resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID);
+ resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID, false);
if (!resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID))
- resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID);
+ resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID, false);
mon_event_all[QOS_L3_MBM_TOTAL_EVENT_ID].evt_cfg = r->mon.mbm_cfg_mask;
mon_event_all[QOS_L3_MBM_LOCAL_EVENT_ID].evt_cfg = r->mon.mbm_cfg_mask &
(READS_TO_LOCAL_MEM |
--
2.51.0
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