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 a variant of
cpumask_any_but() when selecting the CPU. -1 is used to indicate no CPUs
need excluding.
A subsequent patch moves these calls to be before CPUs have been removed,
so this exclude_cpus behaviour is temporary.
Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Signed-off-by: James Morse <james.morse@arm.com>
---
Changes since v2:
* Rephrased a comment to avoid a two letter bad-word. (we)
* Avoid assigning mbm_work_cpu if the domain is going to be free()d
* Added cpumask_any_housekeeping_but(), I dislike the name
Changes since v3:
* Marked an explanatory comment as temporary as the subsequent patch is
no longer adjacent.
---
arch/x86/kernel/cpu/resctrl/core.c | 8 +++--
arch/x86/kernel/cpu/resctrl/internal.h | 37 +++++++++++++++++++++--
arch/x86/kernel/cpu/resctrl/monitor.c | 42 +++++++++++++++++++++-----
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 6 ++--
include/linux/resctrl.h | 3 ++
5 files changed, 82 insertions(+), 14 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index e00f3542e60e..187ed127a446 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -582,12 +582,16 @@ 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);
+ /*
+ * temporary: exclude_cpu=-1 as this CPU has already
+ * been removed by cpumask_clear_cpu()d
+ */
+ mbm_setup_overflow_handler(d, 0, RESCTRL_PICK_ANY_CPU);
}
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);
+ cqm_setup_limbo_handler(d, 0, RESCTRL_PICK_ANY_CPU);
}
}
}
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 021a8956518c..9cba8fc405b9 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -79,6 +79,37 @@ static inline unsigned int cpumask_any_housekeeping(const struct cpumask *mask)
return cpu;
}
+/**
+ * cpumask_any_housekeeping_but() - Chose any cpu in @mask, preferring those
+ * that aren't marked nohz_full, excluding
+ * the provided CPU
+ * @mask: The mask to pick a CPU from.
+ * @exclude_cpu:The CPU to avoid picking.
+ *
+ * Returns a CPU from @mask, but not @but. If there are housekeeping CPUs that
+ * don't use nohz_full, these are preferred.
+ * Returns >= nr_cpu_ids if no CPUs are available.
+ */
+static inline unsigned int
+cpumask_any_housekeeping_but(const struct cpumask *mask, int exclude_cpu)
+{
+ int cpu, hk_cpu;
+
+ cpu = cpumask_any_but(mask, exclude_cpu);
+ if (tick_nohz_full_cpu(cpu)) {
+ hk_cpu = cpumask_nth_andnot(0, mask, tick_nohz_full_mask);
+ if (hk_cpu == exclude_cpu) {
+ hk_cpu = cpumask_nth_andnot(1, mask,
+ tick_nohz_full_mask);
+ }
+
+ if (hk_cpu < nr_cpu_ids)
+ cpu = hk_cpu;
+ }
+
+ return cpu;
+}
+
struct rdt_fs_context {
struct kernfs_fs_context kfc;
bool enable_cdpl2;
@@ -564,11 +595,13 @@ 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 ced933694f60..ae02185f3354 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -485,7 +485,7 @@ 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++;
}
@@ -810,15 +810,28 @@ 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_housekeeping(&dom->cpu_mask);
- dom->cqm_work_cpu = cpu;
+ if (exclude_cpu == RESCTRL_PICK_ANY_CPU)
+ cpu = cpumask_any_housekeeping(&dom->cpu_mask);
+ else
+ cpu = cpumask_any_housekeeping_but(&dom->cpu_mask,
+ exclude_cpu);
- schedule_delayed_work_on(cpu, &dom->cqm_limbo, delay);
+ if (cpu < nr_cpu_ids) {
+ dom->cqm_work_cpu = cpu;
+ schedule_delayed_work_on(cpu, &dom->cqm_limbo, delay);
+ }
}
void mbm_handle_overflow(struct work_struct *work)
@@ -864,7 +877,14 @@ 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;
@@ -875,9 +895,15 @@ void mbm_setup_overflow_handler(struct rdt_domain *dom, unsigned long delay_ms)
*/
if (!resctrl_mounted || !resctrl_arch_mon_capable())
return;
- cpu = cpumask_any_housekeeping(&dom->cpu_mask);
+ if (exclude_cpu == -1)
+ cpu = cpumask_any_housekeeping(&dom->cpu_mask);
+ else
+ cpu = cpumask_any_housekeeping_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 7c3de5ea0482..3373b11afe01 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -2539,7 +2539,8 @@ 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,
+ RESCTRL_PICK_ANY_CPU);
}
goto out;
@@ -3709,7 +3710,8 @@ 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,
+ RESCTRL_PICK_ANY_CPU);
}
if (is_llc_occupancy_enabled())
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index ecd41762d61a..089b91133e5e 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -9,6 +9,9 @@
/* CLOSID value used by the default control group */
#define RESCTRL_RESERVED_CLOSID 0
+/* Indicates no CPU needs to be excluded */
+#define RESCTRL_PICK_ANY_CPU -1
+
#ifdef CONFIG_PROC_CPU_RESCTRL
int proc_resctrl_show(struct seq_file *m,
--
2.39.2Hi James,
On 5/25/2023 11:02 AM, James Morse wrote:
...
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 021a8956518c..9cba8fc405b9 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -79,6 +79,37 @@ static inline unsigned int cpumask_any_housekeeping(const struct cpumask *mask)
> return cpu;
> }
>
> +/**
> + * cpumask_any_housekeeping_but() - Chose any cpu in @mask, preferring those
> + * that aren't marked nohz_full, excluding
> + * the provided CPU
> + * @mask: The mask to pick a CPU from.
> + * @exclude_cpu:The CPU to avoid picking.
> + *
> + * Returns a CPU from @mask, but not @but. If there are housekeeping CPUs that
"but not @exclude_cpu"
> + * don't use nohz_full, these are preferred.
> + * Returns >= nr_cpu_ids if no CPUs are available.
> + */
> +static inline unsigned int
> +cpumask_any_housekeeping_but(const struct cpumask *mask, int exclude_cpu)
> +{
> + int cpu, hk_cpu;
Should these be unsigned int?
> +
> + cpu = cpumask_any_but(mask, exclude_cpu);
> + if (tick_nohz_full_cpu(cpu)) {
> + hk_cpu = cpumask_nth_andnot(0, mask, tick_nohz_full_mask);
> + if (hk_cpu == exclude_cpu) {
> + hk_cpu = cpumask_nth_andnot(1, mask,
> + tick_nohz_full_mask);
> + }
> +
These braces are not necessary. If they are added to help readability then
perhaps the indentation can be reduced by using an earlier:
if (!tick_nohz_full_cpu(cpu))
return cpu;
> + if (hk_cpu < nr_cpu_ids)
> + cpu = hk_cpu;
> + }
> +
> + return cpu;
> +}
> +
> struct rdt_fs_context {
> struct kernfs_fs_context kfc;
> bool enable_cdpl2;
> @@ -564,11 +595,13 @@ 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 ced933694f60..ae02185f3354 100644
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -485,7 +485,7 @@ 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);
Should this -1 be RESCTRL_PICK_ANY_CPU?
> set_bit(idx, d->rmid_busy_llc);
> entry->busy++;
> }
> @@ -810,15 +810,28 @@ 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.
Should -1 be RESCTRL_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_housekeeping(&dom->cpu_mask);
> - dom->cqm_work_cpu = cpu;
> + if (exclude_cpu == RESCTRL_PICK_ANY_CPU)
> + cpu = cpumask_any_housekeeping(&dom->cpu_mask);
> + else
> + cpu = cpumask_any_housekeeping_but(&dom->cpu_mask,
> + exclude_cpu);
>
> - schedule_delayed_work_on(cpu, &dom->cqm_limbo, delay);
> + if (cpu < nr_cpu_ids) {
> + dom->cqm_work_cpu = cpu;
Should cqm_work_cpu not perhaps be set to nr_cpu_ids on failure? If it keeps
pointing to CPU that ran worker previously there may be unexpected behavior.
Note the different behavior between cqm_setup_limbo_handler() and
mbm_setup_overflow_handler() in this regard.
> + schedule_delayed_work_on(cpu, &dom->cqm_limbo, delay);
> + }
> }
>
> void mbm_handle_overflow(struct work_struct *work)
> @@ -864,7 +877,14 @@ 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.
RESCTRL_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;
> @@ -875,9 +895,15 @@ void mbm_setup_overflow_handler(struct rdt_domain *dom, unsigned long delay_ms)
> */
> if (!resctrl_mounted || !resctrl_arch_mon_capable())
> return;
> - cpu = cpumask_any_housekeeping(&dom->cpu_mask);
> + if (exclude_cpu == -1)
same
> + cpu = cpumask_any_housekeeping(&dom->cpu_mask);
> + else
> + cpu = cpumask_any_housekeeping_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);
> }
>
...
> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> index ecd41762d61a..089b91133e5e 100644
> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
> @@ -9,6 +9,9 @@
> /* CLOSID value used by the default control group */
> #define RESCTRL_RESERVED_CLOSID 0
>
> +/* Indicates no CPU needs to be excluded */
This comment seems to just be a rewrite of the macro name.
> +#define RESCTRL_PICK_ANY_CPU -1
> +
> #ifdef CONFIG_PROC_CPU_RESCTRL
>
> int proc_resctrl_show(struct seq_file *m,
Reinette
Hi Reinette,
On 15/06/2023 23:25, Reinette Chatre wrote:
> On 5/25/2023 11:02 AM, James Morse wrote:
>> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
>> index 021a8956518c..9cba8fc405b9 100644
>> --- a/arch/x86/kernel/cpu/resctrl/internal.h
>> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
>> @@ -79,6 +79,37 @@ static inline unsigned int cpumask_any_housekeeping(const struct cpumask *mask)
>> return cpu;
>> }
>>
>> +/**
>> + * cpumask_any_housekeeping_but() - Chose any cpu in @mask, preferring those
>> + * that aren't marked nohz_full, excluding
>> + * the provided CPU
>> + * @mask: The mask to pick a CPU from.
>> + * @exclude_cpu:The CPU to avoid picking.
>> + *
>> + * Returns a CPU from @mask, but not @but. If there are housekeeping CPUs that
>
> "but not @exclude_cpu"
>
>> + * don't use nohz_full, these are preferred.
>> + * Returns >= nr_cpu_ids if no CPUs are available.
>> + */
>> +static inline unsigned int
>> +cpumask_any_housekeeping_but(const struct cpumask *mask, int exclude_cpu)
>> +{
>> + int cpu, hk_cpu;
>
> Should these be unsigned int?
Yup, fixed.
>> +
>> + cpu = cpumask_any_but(mask, exclude_cpu);
>> + if (tick_nohz_full_cpu(cpu)) {
>> + hk_cpu = cpumask_nth_andnot(0, mask, tick_nohz_full_mask);
>> + if (hk_cpu == exclude_cpu) {
>> + hk_cpu = cpumask_nth_andnot(1, mask,
>> + tick_nohz_full_mask);
>> + }
>> +
>
> These braces are not necessary.
My C parser is pretty dumb, and is easily confused by things like that....
> If they are added to help readability then
> perhaps the indentation can be reduced by using an earlier:
>
> if (!tick_nohz_full_cpu(cpu))
> return cpu;
Even better!
>> + if (hk_cpu < nr_cpu_ids)
>> + cpu = hk_cpu;
>> + }
>> +
>> + return cpu;
>> +}
>> +
>> struct rdt_fs_context {
>> struct kernfs_fs_context kfc;
>> bool enable_cdpl2;
>> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
>> index ced933694f60..ae02185f3354 100644
>> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
>> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
>> @@ -485,7 +485,7 @@ 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);
>
> Should this -1 be RESCTRL_PICK_ANY_CPU?
>
>> set_bit(idx, d->rmid_busy_llc);
>> entry->busy++;
>> }
>> @@ -810,15 +810,28 @@ 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.
>
> Should -1 be RESCTRL_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_housekeeping(&dom->cpu_mask);
>> - dom->cqm_work_cpu = cpu;
>> + if (exclude_cpu == RESCTRL_PICK_ANY_CPU)
>> + cpu = cpumask_any_housekeeping(&dom->cpu_mask);
>> + else
>> + cpu = cpumask_any_housekeeping_but(&dom->cpu_mask,
>> + exclude_cpu);
>>
>> - schedule_delayed_work_on(cpu, &dom->cqm_limbo, delay);
>> + if (cpu < nr_cpu_ids) {
>> + dom->cqm_work_cpu = cpu;
>
> Should cqm_work_cpu not perhaps be set to nr_cpu_ids on failure? If it keeps
> pointing to CPU that ran worker previously there may be unexpected behavior.
>
> Note the different behavior between cqm_setup_limbo_handler() and
> mbm_setup_overflow_handler() in this regard.
Sure,
>> + schedule_delayed_work_on(cpu, &dom->cqm_limbo, delay);
>> + }
>> }
>>
>> void mbm_handle_overflow(struct work_struct *work)
>> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
>> index ecd41762d61a..089b91133e5e 100644
>> --- a/include/linux/resctrl.h
>> +++ b/include/linux/resctrl.h
>> @@ -9,6 +9,9 @@
>> /* CLOSID value used by the default control group */
>> #define RESCTRL_RESERVED_CLOSID 0
>>
>> +/* Indicates no CPU needs to be excluded */
>
> This comment seems to just be a rewrite of the macro name.
I'm more than happy to remove it!
Thanks,
James
Hi James,
> 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 a variant of
> cpumask_any_but() when selecting the CPU. -1 is used to indicate no CPUs
> need excluding.
>
> A subsequent patch moves these calls to be before CPUs have been removed,
> so this exclude_cpus behaviour is temporary.
>
> Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
> Signed-off-by: James Morse <james.morse@arm.com>
> ---
> Changes since v2:
> * Rephrased a comment to avoid a two letter bad-word. (we)
> * Avoid assigning mbm_work_cpu if the domain is going to be free()d
> * Added cpumask_any_housekeeping_but(), I dislike the name
>
> Changes since v3:
> * Marked an explanatory comment as temporary as the subsequent patch is
> no longer adjacent.
> ---
> arch/x86/kernel/cpu/resctrl/core.c | 8 +++--
> arch/x86/kernel/cpu/resctrl/internal.h | 37
> +++++++++++++++++++++-- arch/x86/kernel/cpu/resctrl/monitor.c
> | 42 +++++++++++++++++++++-----
> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 6 ++--
> include/linux/resctrl.h | 3 ++
> 5 files changed, 82 insertions(+), 14 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/resctrl/core.c
> b/arch/x86/kernel/cpu/resctrl/core.c
> index e00f3542e60e..187ed127a446 100644
> --- a/arch/x86/kernel/cpu/resctrl/core.c
> +++ b/arch/x86/kernel/cpu/resctrl/core.c
> @@ -582,12 +582,16 @@ 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);
> + /*
> + * temporary: exclude_cpu=-1 as this CPU has
> already
> + * been removed by cpumask_clear_cpu()d
> + */
> + mbm_setup_overflow_handler(d, 0,
> RESCTRL_PICK_ANY_CPU);
> }
> 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);
> + cqm_setup_limbo_handler(d, 0,
> RESCTRL_PICK_ANY_CPU);
> }
> }
> }
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h
> b/arch/x86/kernel/cpu/resctrl/internal.h
> index 021a8956518c..9cba8fc405b9 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -79,6 +79,37 @@ static inline unsigned int
> cpumask_any_housekeeping(const struct cpumask *mask)
> return cpu;
> }
>
> +/**
> + * cpumask_any_housekeeping_but() - Chose any cpu in @mask, preferring
> those
> + * that aren't marked nohz_full, excluding
> + * the provided CPU
> + * @mask: The mask to pick a CPU from.
> + * @exclude_cpu:The CPU to avoid picking.
> + *
> + * Returns a CPU from @mask, but not @but. If there are housekeeping
> +CPUs that
> + * don't use nohz_full, these are preferred.
> + * Returns >= nr_cpu_ids if no CPUs are available.
> + */
> +static inline unsigned int
> +cpumask_any_housekeeping_but(const struct cpumask *mask, int
> +exclude_cpu) {
> + int cpu, hk_cpu;
> +
> + cpu = cpumask_any_but(mask, exclude_cpu);
> + if (tick_nohz_full_cpu(cpu)) {
> + hk_cpu = cpumask_nth_andnot(0, mask,
> tick_nohz_full_mask);
> + if (hk_cpu == exclude_cpu) {
> + hk_cpu = cpumask_nth_andnot(1, mask,
> + tick_nohz_full_mask);
> + }
> +
> + if (hk_cpu < nr_cpu_ids)
> + cpu = hk_cpu;
> + }
> +
> + return cpu;
> +}
> +
> struct rdt_fs_context {
> struct kernfs_fs_context kfc;
> bool enable_cdpl2;
> @@ -564,11 +595,13 @@ 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 ced933694f60..ae02185f3354 100644
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -485,7 +485,7 @@ 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++;
> }
> @@ -810,15 +810,28 @@ 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_housekeeping(&dom->cpu_mask);
> - dom->cqm_work_cpu = cpu;
> + if (exclude_cpu == RESCTRL_PICK_ANY_CPU)
> + cpu = cpumask_any_housekeeping(&dom->cpu_mask);
> + else
> + cpu = cpumask_any_housekeeping_but(&dom->cpu_mask,
> + exclude_cpu);
>
> - schedule_delayed_work_on(cpu, &dom->cqm_limbo, delay);
> + if (cpu < nr_cpu_ids) {
> + dom->cqm_work_cpu = cpu;
> + schedule_delayed_work_on(cpu, &dom->cqm_limbo, delay);
> + }
> }
>
> void mbm_handle_overflow(struct work_struct *work) @@ -864,7 +877,14
> @@ 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;
> @@ -875,9 +895,15 @@ void mbm_setup_overflow_handler(struct rdt_domain
> *dom, unsigned long delay_ms)
> */
> if (!resctrl_mounted || !resctrl_arch_mon_capable())
> return;
> - cpu = cpumask_any_housekeeping(&dom->cpu_mask);
> + if (exclude_cpu == -1)
> + cpu = cpumask_any_housekeeping(&dom->cpu_mask);
Should RESCTRL_PICK_ANY_CPU be used instead of -1?
Best regards,
Shaopeng TAN
Hi Shaopeng Tan, On 09/06/2023 12:10, Shaopeng Tan (Fujitsu) wrote: >> 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 a variant of >> cpumask_any_but() when selecting the CPU. -1 is used to indicate no CPUs >> need excluding. >> >> A subsequent patch moves these calls to be before CPUs have been removed, >> so this exclude_cpus behaviour is temporary. >> diff --git >> a/arch/x86/kernel/cpu/resctrl/monitor.c >> b/arch/x86/kernel/cpu/resctrl/monitor.c >> index ced933694f60..ae02185f3354 100644 >> --- a/arch/x86/kernel/cpu/resctrl/monitor.c >> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c >> @@ -875,9 +895,15 @@ void mbm_setup_overflow_handler(struct rdt_domain >> *dom, unsigned long delay_ms) >> */ >> if (!resctrl_mounted || !resctrl_arch_mon_capable()) >> return; >> - cpu = cpumask_any_housekeeping(&dom->cpu_mask); >> + if (exclude_cpu == -1) >> + cpu = cpumask_any_housekeeping(&dom->cpu_mask); > > Should RESCTRL_PICK_ANY_CPU be used instead of -1? Yup, that would be more readable. I did this for cqm_setup_limbo_handler(), but for some reason missed this one. Thanks, James
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