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Message-Id: <20221021131204.5581-17-james.morse@arm.com>
Date: Fri, 21 Oct 2022 13:12:02 +0000
From: James Morse <james.morse@....com>
To: x86@...nel.org, linux-kernel@...r.kernel.org
Cc: Fenghua Yu <fenghua.yu@...el.com>,
Reinette Chatre <reinette.chatre@...el.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
H Peter Anvin <hpa@...or.com>,
Babu Moger <Babu.Moger@....com>,
James Morse <james.morse@....com>,
shameerali.kolothum.thodi@...wei.com,
D Scott Phillips OS <scott@...amperecomputing.com>,
carl@...amperecomputing.com, lcherian@...vell.com,
bobo.shaobowang@...wei.com, tan.shaopeng@...itsu.com,
Jamie Iles <quic_jiles@...cinc.com>,
Xin Hao <xhao@...ux.alibaba.com>, xingxin.hx@...nanolis.org,
baolin.wang@...ux.alibaba.com, peternewman@...gle.com
Subject: [PATCH 16/18] x86/resctrl: Allow overflow/limbo handlers to be scheduled on any-but cpu
When a cpu is taken offline resctrl may need to move the overflow or
limbo handlers to run on a different CPU.
Once the offline callbacks have been split, cqm_setup_limbo_handler()
will be called while the CPU that is going offline is still present
in the cpu_mask.
Pass the CPU to exclude to cqm_setup_limbo_handler() and
mbm_setup_overflow_handler(). These functions can use cpumask_any_but()
when selecting the CPU. -1 is used to indicate no CPUs need excluding.
Signed-off-by: James Morse <james.morse@....com>
---
Both cpumask_any() and cpumask_any_but() return a value >= nr_cpu_ids
on error. schedule_delayed_work_on() doesn't appear to check. Add the
error handling to be robust. It doesn't look like its possible to hit
this.
---
arch/x86/kernel/cpu/resctrl/core.c | 6 ++--
arch/x86/kernel/cpu/resctrl/internal.h | 6 ++--
arch/x86/kernel/cpu/resctrl/monitor.c | 39 +++++++++++++++++++++-----
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 4 +--
4 files changed, 42 insertions(+), 13 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 511ced743a79..e25d7a581b0d 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -563,12 +563,14 @@ static void domain_remove_cpu(int cpu, struct rdt_resource *r)
if (r == &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl) {
if (is_mbm_enabled() && cpu == d->mbm_work_cpu) {
cancel_delayed_work(&d->mbm_over);
- mbm_setup_overflow_handler(d, 0);
+ /* exclude_cpu=-1 as we already cpumask_clear_cpu()d */
+ mbm_setup_overflow_handler(d, 0, -1);
}
if (is_llc_occupancy_enabled() && cpu == d->cqm_work_cpu &&
has_busy_rmid(r, d)) {
cancel_delayed_work(&d->cqm_limbo);
- cqm_setup_limbo_handler(d, 0);
+ /* exclude_cpu=-1 as we already cpumask_clear_cpu()d */
+ cqm_setup_limbo_handler(d, 0, -1);
}
}
}
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index adbbfaabf70b..96535e359382 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -525,11 +525,13 @@ void mon_event_read(struct rmid_read *rr, struct rdt_resource *r,
struct rdt_domain *d, struct rdtgroup *rdtgrp,
int evtid, int first);
void mbm_setup_overflow_handler(struct rdt_domain *dom,
- unsigned long delay_ms);
+ unsigned long delay_ms,
+ int exclude_cpu);
void mbm_handle_overflow(struct work_struct *work);
void __init intel_rdt_mbm_apply_quirk(void);
bool is_mba_sc(struct rdt_resource *r);
-void cqm_setup_limbo_handler(struct rdt_domain *dom, unsigned long delay_ms);
+void cqm_setup_limbo_handler(struct rdt_domain *dom, unsigned long delay_ms,
+ int exclude_cpu);
void cqm_handle_limbo(struct work_struct *work);
bool has_busy_rmid(struct rdt_resource *r, struct rdt_domain *d);
void __check_limbo(struct rdt_domain *d, bool force_free);
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index a9af7c56a04a..42a7fd6d56c9 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -433,7 +433,7 @@ static void add_rmid_to_limbo(struct rmid_entry *entry)
* setup up the limbo worker.
*/
if (!has_busy_rmid(r, d))
- cqm_setup_limbo_handler(d, CQM_LIMBOCHECK_INTERVAL);
+ cqm_setup_limbo_handler(d, CQM_LIMBOCHECK_INTERVAL, -1);
set_bit(idx, d->rmid_busy_llc);
entry->busy++;
}
@@ -766,15 +766,27 @@ void cqm_handle_limbo(struct work_struct *work)
mutex_unlock(&rdtgroup_mutex);
}
-void cqm_setup_limbo_handler(struct rdt_domain *dom, unsigned long delay_ms)
+/**
+ * cqm_setup_limbo_handler() - Schedule the limbo handler to run for this
+ * domain.
+ * @delay_ms: How far in the future the handler should run.
+ * @exclude_cpu: Which CPU the handler should not run on, -1 to pick any CPU.
+ */
+void cqm_setup_limbo_handler(struct rdt_domain *dom, unsigned long delay_ms,
+ int exclude_cpu)
{
unsigned long delay = msecs_to_jiffies(delay_ms);
int cpu;
- cpu = cpumask_any(&dom->cpu_mask);
+ if (exclude_cpu == -1)
+ cpu = cpumask_any(&dom->cpu_mask);
+ else
+ cpu = cpumask_any_but(&dom->cpu_mask, exclude_cpu);
+
dom->cqm_work_cpu = cpu;
- schedule_delayed_work_on(cpu, &dom->cqm_limbo, delay);
+ if (cpu < nr_cpu_ids)
+ schedule_delayed_work_on(cpu, &dom->cqm_limbo, delay);
}
void mbm_handle_overflow(struct work_struct *work)
@@ -811,7 +823,14 @@ void mbm_handle_overflow(struct work_struct *work)
mutex_unlock(&rdtgroup_mutex);
}
-void mbm_setup_overflow_handler(struct rdt_domain *dom, unsigned long delay_ms)
+/**
+ * mbm_setup_overflow_handler() - Schedule the overflow handler to run for this
+ * domain.
+ * @delay_ms: How far in the future the handler should run.
+ * @exclude_cpu: Which CPU the handler should not run on, -1 to pick any CPU.
+ */
+void mbm_setup_overflow_handler(struct rdt_domain *dom, unsigned long delay_ms,
+ int exclude_cpu)
{
unsigned long delay = msecs_to_jiffies(delay_ms);
int cpu;
@@ -819,9 +838,15 @@ void mbm_setup_overflow_handler(struct rdt_domain *dom, unsigned long delay_ms)
if (!resctrl_mounted || !resctrl_arch_mon_capable())
return;
- cpu = cpumask_any(&dom->cpu_mask);
+ if (exclude_cpu == -1)
+ cpu = cpumask_any(&dom->cpu_mask);
+ else
+ cpu = cpumask_any_but(&dom->cpu_mask, exclude_cpu);
+
dom->mbm_work_cpu = cpu;
- schedule_delayed_work_on(cpu, &dom->mbm_over, delay);
+
+ if (cpu < nr_cpu_ids)
+ schedule_delayed_work_on(cpu, &dom->mbm_over, delay);
}
static int dom_data_init(struct rdt_resource *r)
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index ef444a5690e9..3d68a9cb1942 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -2254,7 +2254,7 @@ static int rdt_get_tree(struct fs_context *fc)
if (is_mbm_enabled()) {
r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
list_for_each_entry(dom, &r->domains, list)
- mbm_setup_overflow_handler(dom, MBM_OVERFLOW_INTERVAL);
+ mbm_setup_overflow_handler(dom, MBM_OVERFLOW_INTERVAL, -1);
}
goto out;
@@ -3413,7 +3413,7 @@ int resctrl_online_domain(struct rdt_resource *r, struct rdt_domain *d)
if (is_mbm_enabled()) {
INIT_DELAYED_WORK(&d->mbm_over, mbm_handle_overflow);
- mbm_setup_overflow_handler(d, MBM_OVERFLOW_INTERVAL);
+ mbm_setup_overflow_handler(d, MBM_OVERFLOW_INTERVAL, -1);
}
if (is_llc_occupancy_enabled())
--
2.30.2
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