Messages in this thread Patch in this message | | | From | James Morse <> | Subject | [PATCH v4 21/24] x86/resctrl: Allow overflow/limbo handlers to be scheduled on any-but cpu | Date | Thu, 25 May 2023 18:02:06 +0000 |
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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, -- 2.39.2
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