Messages in this thread | | | Date | Thu, 9 Nov 2023 14:51:57 -0600 | From | "Moger, Babu" <> | Subject | Re: [PATCH v7 21/24] x86/resctrl: Allow overflow/limbo handlers to be scheduled on any-but cpu |
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On 10/25/23 13:03, James Morse 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. > > Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com> > Tested-by: Peter Newman <peternewman@google.com> > Reviewed-by: Shaopeng Tan <tan.shaopeng@fujitsu.com> > Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Babu Moger <babu.moger@amd.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. > > Changes since v4: > * Check against RESCTRL_PICK_ANY_CPU instead of -1. > * Leave cqm_work_cpu as nr_cpu_ids when no CPU is available. > * Made cpumask_any_housekeeping_but() more readable. > > Changes since v5: > * Changes in captialisation, and a typo. > * Merged cpumask helpers. > > Changes since v6: > * Added the missing dom parameter to some kernel doc. > * Re-added use of cpumask_any_but(), > * Expanded comment above cpumask_any_housekeeping(), > * Added some more comments for good measure. > * Added explicit IS_ENABLED() check as gcc-12 doesn't seem to work this out. > --- > arch/x86/kernel/cpu/resctrl/core.c | 8 +++-- > arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 2 +- > arch/x86/kernel/cpu/resctrl/internal.h | 33 ++++++++++++++---- > arch/x86/kernel/cpu/resctrl/monitor.c | 42 ++++++++++++++++++----- > arch/x86/kernel/cpu/resctrl/rdtgroup.c | 6 ++-- > include/linux/resctrl.h | 2 ++ > 6 files changed, 72 insertions(+), 21 deletions(-) > > diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c > index 1a74e9c47416..7e44f2c40897 100644 > --- a/arch/x86/kernel/cpu/resctrl/core.c > +++ b/arch/x86/kernel/cpu/resctrl/core.c > @@ -586,12 +586,16 @@ 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(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/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c > index a033e8e32108..64db51455df3 100644 > --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c > +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c > @@ -552,7 +552,7 @@ void mon_event_read(struct rmid_read *rr, struct rdt_resource *r, > return; > } > > - cpu = cpumask_any_housekeeping(&d->cpu_mask); > + cpu = cpumask_any_housekeeping(&d->cpu_mask, RESCTRL_PICK_ANY_CPU); > > /* > * cpumask_any_housekeeping() prefers housekeeping CPUs, but > diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h > index c4c1e1909058..f5fff2f0d866 100644 > --- a/arch/x86/kernel/cpu/resctrl/internal.h > +++ b/arch/x86/kernel/cpu/resctrl/internal.h > @@ -61,19 +61,36 @@ > * cpumask_any_housekeeping() - Choose any CPU in @mask, preferring those that > * aren't marked nohz_full > * @mask: The mask to pick a CPU from. > + * @exclude_cpu:The CPU to avoid picking. > * > - * Returns a CPU in @mask. If there are housekeeping CPUs that don't use > - * nohz_full, these are preferred. > + * Returns a CPU from @mask, but not @exclude_cpu. If there are housekeeping > + * CPUs that don't use nohz_full, these are preferred. Pass > + * RESCTRL_PICK_ANY_CPU to avoid excluding any CPUs. > + * > + * When a CPU is excluded, returns >= nr_cpu_ids if no CPUs are available. > */ > -static inline unsigned int cpumask_any_housekeeping(const struct cpumask *mask) > +static inline unsigned int > +cpumask_any_housekeeping(const struct cpumask *mask, int exclude_cpu) > { > unsigned int cpu, hk_cpu; > > - cpu = cpumask_any(mask); > - if (!tick_nohz_full_cpu(cpu)) > + if (exclude_cpu == RESCTRL_PICK_ANY_CPU) > + cpu = cpumask_any(mask); > + else > + cpu = cpumask_any_but(mask, exclude_cpu); > + > + if (!IS_ENABLED(CONFIG_NO_HZ_FULL)) > + return cpu; > + > + /* If the CPU picked isn't marked nohz_full, we're done */ > + if (cpu <= nr_cpu_ids && !tick_nohz_full_cpu(cpu)) > return cpu; > > + /* Try to find a CPU that isn't nohz_full to use in preference */ > 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; > > @@ -575,11 +592,13 @@ 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_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 87379d2a339c..241b3dd8646c 100644 > --- a/arch/x86/kernel/cpu/resctrl/monitor.c > +++ b/arch/x86/kernel/cpu/resctrl/monitor.c > @@ -481,7 +481,8 @@ static void add_rmid_to_limbo(struct rmid_entry *entry) > * setup up the limbo worker. > */ > if (!has_busy_rmid(d)) > - cqm_setup_limbo_handler(d, CQM_LIMBOCHECK_INTERVAL); > + cqm_setup_limbo_handler(d, CQM_LIMBOCHECK_INTERVAL, > + RESCTRL_PICK_ANY_CPU); > set_bit(idx, d->rmid_busy_llc); > entry->busy++; > } > @@ -808,7 +809,8 @@ void cqm_handle_limbo(struct work_struct *work) > __check_limbo(d, false); > > if (has_busy_rmid(d)) { > - d->cqm_work_cpu = cpumask_any_housekeeping(&d->cpu_mask); > + d->cqm_work_cpu = cpumask_any_housekeeping(&d->cpu_mask, > + RESCTRL_PICK_ANY_CPU); > schedule_delayed_work_on(d->cqm_work_cpu, &d->cqm_limbo, > delay); > } > @@ -816,15 +818,25 @@ 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. > + * @dom: The domain the limbo handler should run for. > + * @delay_ms: How far in the future the handler should run. > + * @exclude_cpu: Which CPU the handler should not run on, > + * RESCTRL_PICK_ANY_CPU 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); > + cpu = cpumask_any_housekeeping(&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) > @@ -862,14 +874,24 @@ void mbm_handle_overflow(struct work_struct *work) > * Re-check for housekeeping CPUs. This allows the overflow handler to > * move off a nohz_full CPU quickly. > */ > - d->mbm_work_cpu = cpumask_any_housekeeping(&d->cpu_mask); > + d->mbm_work_cpu = cpumask_any_housekeeping(&d->cpu_mask, > + RESCTRL_PICK_ANY_CPU); > schedule_delayed_work_on(d->mbm_work_cpu, &d->mbm_over, delay); > > out_unlock: > 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. > + * @dom: The domain the overflow handler should run for. > + * @delay_ms: How far in the future the handler should run. > + * @exclude_cpu: Which CPU the handler should not run on, > + * RESCTRL_PICK_ANY_CPU 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; > @@ -880,9 +902,11 @@ 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); > + cpu = cpumask_any_housekeeping(&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 ab9db7ce706f..e22e0f6adeb3 100644 > --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c > +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c > @@ -2683,7 +2683,8 @@ 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; > @@ -3994,7 +3995,8 @@ 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 4c4bad3c34e4..ccbbbe5d18d3 100644 > --- a/include/linux/resctrl.h > +++ b/include/linux/resctrl.h > @@ -10,6 +10,8 @@ > #define RESCTRL_RESERVED_CLOSID 0 > #define RESCTRL_RESERVED_RMID 0 > > +#define RESCTRL_PICK_ANY_CPU -1 > + > #ifdef CONFIG_PROC_CPU_RESCTRL > > int proc_resctrl_show(struct seq_file *m,
-- Thanks Babu Moger
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