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From: Jan Beulich <jbeulich@suse.com>
To: Juergen Gross <jgross@suse.com>
Cc: Tim Deegan <tim@xen.org>,
	Stefano Stabellini <sstabellini@kernel.org>, Wei Liu <wl@xen.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	George Dunlap <George.Dunlap@eu.citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Ian Jackson <ian.jackson@eu.citrix.com>,
	Dario Faggioli <dfaggioli@suse.com>,
	Julien Grall <julien.grall@arm.com>,
	xen-devel@lists.xenproject.org
Subject: Re: [Xen-devel] [PATCH v2 24/48] xen: switch from for_each_vcpu() to for_each_sched_unit()
Date: Mon, 9 Sep 2019 17:14:10 +0200
Message-ID: <de1280ef-a2f0-b96c-8c7a-049027cf1b34@suse.com> (raw)
In-Reply-To: <20190809145833.1020-25-jgross@suse.com>

On 09.08.2019 16:58, Juergen Gross wrote:
> @@ -504,22 +511,21 @@ int sched_move_domain(struct domain *d, struct cpupool *c)
>      if ( IS_ERR(domdata) )
>          return PTR_ERR(domdata);
>  
> -    vcpu_priv = xzalloc_array(void *, d->max_vcpus);
> -    if ( vcpu_priv == NULL )
> +    unit_priv = xzalloc_array(void *, d->max_vcpus);

I find it confusing that an array of units (as per the use below)
is dimensioned by the domain's vCPU count. Isn't there a correlation
between vCPU IDs and units IDs, perhaps along the lines of CPU
APIC (thread), core, and socket IDs? If so, the array size could
be bounded here by a smaller (down the road) value.

> @@ -880,18 +889,36 @@ void vcpu_force_reschedule(struct vcpu *v)
>      vcpu_migrate_finish(v);
>  }
>  
> +static bool sched_check_affinity_broken(struct sched_unit *unit)

const

> +{
> +    struct vcpu *v;

const

> @@ -910,18 +937,20 @@ void restore_vcpu_affinity(struct domain *d)
>                      cpupool_domain_cpumask(d));
>          if ( cpumask_empty(cpumask_scratch_cpu(cpu)) )
>          {
> -            if ( v->affinity_broken )
> +            if ( sched_check_affinity_broken(unit) )
>              {
> -                sched_set_affinity(v, unit->cpu_hard_affinity_saved, NULL);
> -                v->affinity_broken = 0;
> +                sched_set_affinity(unit->vcpu_list,
> +                                   unit->cpu_hard_affinity_saved, NULL);
> +                sched_reset_affinity_broken(unit);
>                  cpumask_and(cpumask_scratch_cpu(cpu), unit->cpu_hard_affinity,
>                              cpupool_domain_cpumask(d));
>              }
>  
>              if ( cpumask_empty(cpumask_scratch_cpu(cpu)) )
>              {
> -                printk(XENLOG_DEBUG "Breaking affinity for %pv\n", v);
> -                sched_set_affinity(v, &cpumask_all, NULL);
> +                printk(XENLOG_DEBUG "Breaking affinity for %pv\n",
> +                       unit->vcpu_list);
> +                sched_set_affinity(unit->vcpu_list, &cpumask_all, NULL);
>                  cpumask_and(cpumask_scratch_cpu(cpu), unit->cpu_hard_affinity,
>                              cpupool_domain_cpumask(d));
>              }
>[...]> @@ -964,17 +992,18 @@ int cpu_disable_scheduler(unsigned int cpu)
>  
>      for_each_domain_in_cpupool ( d, c )
>      {
> -        for_each_vcpu ( d, v )
> +        struct sched_unit *unit;
> +
> +        for_each_sched_unit ( d, unit )
>          {
>              unsigned long flags;
> -            struct sched_unit *unit = v->sched_unit;
>              spinlock_t *lock = unit_schedule_lock_irqsave(unit, &flags);
>  
>              cpumask_and(&online_affinity, unit->cpu_hard_affinity, c->cpu_valid);
>              if ( cpumask_empty(&online_affinity) &&
>                   cpumask_test_cpu(cpu, unit->cpu_hard_affinity) )
>              {
> -                if ( v->affinity_broken )
> +                if ( unit->vcpu_list->affinity_broken )
>                  {
>                      /* The vcpu is temporarily pinned, can't move it. */
>                      unit_schedule_unlock_irqrestore(lock, flags, unit);
> @@ -982,14 +1011,15 @@ int cpu_disable_scheduler(unsigned int cpu)
>                      break;
>                  }
>  
> -                printk(XENLOG_DEBUG "Breaking affinity for %pv\n", v);
> +                printk(XENLOG_DEBUG "Breaking affinity for %pv\n",
> +                       unit->vcpu_list);
>  
> -                sched_set_affinity(v, &cpumask_all, NULL);
> +                sched_set_affinity(unit->vcpu_list, &cpumask_all, NULL);
>              }
>  
> -            if ( v->processor != cpu )
> +            if ( sched_unit_cpu(unit) != sched_get_resource_cpu(cpu) )
>              {
> -                /* The vcpu is not on this cpu, so we can move on. */
> +                /* The unit is not on this cpu, so we can move on. */
>                  unit_schedule_unlock_irqrestore(lock, flags, unit);
>                  continue;
>              }
> @@ -1002,17 +1032,17 @@ int cpu_disable_scheduler(unsigned int cpu)
>               *  * the scheduler will always find a suitable solution, or
>               *    things would have failed before getting in here.
>               */
> -            vcpu_migrate_start(v);
> +            vcpu_migrate_start(unit->vcpu_list);
>              unit_schedule_unlock_irqrestore(lock, flags, unit);
>  
> -            vcpu_migrate_finish(v);
> +            vcpu_migrate_finish(unit->vcpu_list);

All the ->vcpu_list references look bogus considering where you're
moving, but I can only guess that all of this will need touching
again later in the series. I wonder though whether these wouldn't
better change into for-each-vCPU-in-unit loops right away.

>              /*
>               * The only caveat, in this case, is that if a vcpu active in
>               * the hypervisor isn't migratable. In this case, the caller
>               * should try again after releasing and reaquiring all locks.
>               */
> -            if ( v->processor == cpu )
> +            if ( sched_unit_cpu(unit) == sched_get_resource_cpu(cpu) )

Is comparing the (pseudo) CPU values here the most efficient approach
generated code wise? Can't there be some pointer comparison that's
cheaper?

> @@ -1023,8 +1053,8 @@ int cpu_disable_scheduler(unsigned int cpu)
>  static int cpu_disable_scheduler_check(unsigned int cpu)
>  {
>      struct domain *d;
> -    struct vcpu *v;
>      struct cpupool *c;
> +    struct vcpu *v;
>  
>      c = per_cpu(cpupool, cpu);
>      if ( c == NULL )

Stray change?

Jan

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  reply index

Thread overview: 126+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-09 14:57 [Xen-devel] [PATCH v2 00/48] xen: add core scheduling support Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 01/48] xen/sched: use new sched_unit instead of vcpu in scheduler interfaces Juergen Gross
2019-09-02  9:07   ` Jan Beulich
2019-09-09  5:26     ` Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 02/48] xen/sched: move per-vcpu scheduler private data pointer to sched_unit Juergen Gross
2019-08-23 10:47   ` Dario Faggioli
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 03/48] xen/sched: build a linked list of struct sched_unit Juergen Gross
2019-08-23 10:52   ` Dario Faggioli
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 04/48] xen/sched: introduce struct sched_resource Juergen Gross
2019-08-23 10:54   ` Dario Faggioli
2019-09-04 13:10   ` Jan Beulich
2019-09-09  5:31     ` Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 05/48] xen/sched: let pick_cpu return a scheduler resource Juergen Gross
2019-09-04 13:34   ` Jan Beulich
2019-09-09  5:43     ` Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 06/48] xen/sched: switch schedule_data.curr to point at sched_unit Juergen Gross
2019-09-04 13:36   ` Jan Beulich
2019-09-09  5:46     ` Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 07/48] xen/sched: move per cpu scheduler private data into struct sched_resource Juergen Gross
2019-09-04 13:48   ` Jan Beulich
2019-09-05  7:13     ` Juergen Gross
2019-09-05  7:38       ` Jan Beulich
2019-09-09 13:03         ` Dario Faggioli
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 08/48] xen/sched: switch vcpu_schedule_lock to unit_schedule_lock Juergen Gross
2019-09-04 14:02   ` Jan Beulich
2019-09-04 14:41     ` Juergen Gross
2019-09-04 14:54       ` Jan Beulich
2019-09-04 15:02         ` Juergen Gross
2019-09-11 16:02           ` Dario Faggioli
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 09/48] xen/sched: move some per-vcpu items to struct sched_unit Juergen Gross
2019-09-04 14:16   ` Jan Beulich
2019-09-09  6:39     ` Juergen Gross
2019-09-09  6:55       ` Jan Beulich
2019-09-09  7:05         ` Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 10/48] xen/sched: add scheduler helpers hiding vcpu Juergen Gross
2019-09-04 14:49   ` Jan Beulich
2019-09-11 13:22     ` Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 11/48] xen/sched: rename scheduler related perf counters Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 12/48] xen/sched: switch struct task_slice from vcpu to sched_unit Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 13/48] xen/sched: add is_running indicator to struct sched_unit Juergen Gross
2019-09-04 15:06   ` Jan Beulich
2019-09-11 13:44     ` Juergen Gross
2019-09-11 15:06       ` Jan Beulich
2019-09-11 15:32         ` Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 14/48] xen/sched: make null scheduler vcpu agnostic Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 15/48] xen/sched: make rt " Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 16/48] xen/sched: make credit " Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 17/48] xen/sched: make credit2 " Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 18/48] xen/sched: make arinc653 " Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 19/48] xen: add sched_unit_pause_nosync() and sched_unit_unpause() Juergen Gross
2019-09-09 13:34   ` Jan Beulich
2019-09-11 14:15     ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 20/48] xen: let vcpu_create() select processor Juergen Gross
2019-08-23 16:42   ` Julien Grall
2019-09-09 13:38   ` Jan Beulich
2019-09-11 14:22     ` Juergen Gross
2019-09-11 17:20       ` Dario Faggioli
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 21/48] xen/sched: use sched_resource cpu instead smp_processor_id in schedulers Juergen Gross
2019-09-09 14:17   ` Jan Beulich
2019-09-12  9:34     ` Juergen Gross
2019-09-12 10:04       ` Jan Beulich
2019-09-12 11:03         ` Juergen Gross
2019-09-12 11:17         ` Juergen Gross
2019-09-12 11:46           ` Jan Beulich
2019-09-12 11:53             ` Juergen Gross
2019-09-12 12:08               ` Jan Beulich
2019-09-12 12:13                 ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 22/48] xen/sched: switch schedule() from vcpus to sched_units Juergen Gross
2019-09-09 14:35   ` Jan Beulich
2019-09-12 13:44     ` Juergen Gross
2019-09-12 14:34       ` Jan Beulich
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 23/48] xen/sched: switch sched_move_irqs() to take sched_unit as parameter Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 24/48] xen: switch from for_each_vcpu() to for_each_sched_unit() Juergen Gross
2019-09-09 15:14   ` Jan Beulich [this message]
2019-09-12 14:02     ` Juergen Gross
2019-09-12 14:40       ` Jan Beulich
2019-09-12 14:47         ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 25/48] xen/sched: add runstate counters to struct sched_unit Juergen Gross
2019-09-09 14:30   ` Jan Beulich
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 26/48] xen/sched: rework and rename vcpu_force_reschedule() Juergen Gross
2019-09-10 14:06   ` Jan Beulich
2019-09-13  9:33     ` Juergen Gross
2019-09-13  9:40       ` Jan Beulich
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 27/48] xen/sched: Change vcpu_migrate_*() to operate on schedule unit Juergen Gross
2019-09-10 15:11   ` Jan Beulich
2019-09-13 12:33     ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 28/48] xen/sched: move struct task_slice into struct sched_unit Juergen Gross
2019-09-10 15:18   ` Jan Beulich
2019-09-13 12:56     ` Juergen Gross
2019-09-12  8:13   ` Dario Faggioli
2019-09-12  8:21     ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 29/48] xen/sched: add code to sync scheduling of all vcpus of a sched unit Juergen Gross
2019-09-10 15:36   ` Jan Beulich
2019-09-13 13:12     ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 30/48] xen/sched: introduce unit_runnable_state() Juergen Gross
2019-09-11 10:30   ` Jan Beulich
2019-09-12 10:22     ` Dario Faggioli
2019-09-13 14:07     ` Juergen Gross
2019-09-13 14:44       ` Jan Beulich
2019-09-13 15:23         ` Juergen Gross
2019-09-12 10:24   ` Dario Faggioli
2019-09-13 14:14     ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 31/48] xen/sched: add support for multiple vcpus per sched unit where missing Juergen Gross
2019-09-11 10:43   ` Jan Beulich
2019-09-13 15:01     ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 32/48] xen/sched: modify cpupool_domain_cpumask() to be an unit mask Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 33/48] xen/sched: support allocating multiple vcpus into one sched unit Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 34/48] xen/sched: add a percpu resource index Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 35/48] xen/sched: add fall back to idle vcpu when scheduling unit Juergen Gross
2019-09-11 11:33   ` Julien Grall
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 36/48] xen/sched: make vcpu_wake() and vcpu_sleep() core scheduling aware Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 37/48] xen/sched: carve out freeing sched_unit memory into dedicated function Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 38/48] xen/sched: move per-cpu variable scheduler to struct sched_resource Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 39/48] xen/sched: move per-cpu variable cpupool " Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 40/48] xen/sched: reject switching smt on/off with core scheduling active Juergen Gross
2019-09-10 15:47   ` Jan Beulich
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 41/48] xen/sched: prepare per-cpupool scheduling granularity Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 42/48] xen/sched: split schedule_cpu_switch() Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 43/48] xen/sched: protect scheduling resource via rcu Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 44/48] xen/sched: support multiple cpus per scheduling resource Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 45/48] xen/sched: support differing granularity in schedule_cpu_[add/rm]() Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 46/48] xen/sched: support core scheduling for moving cpus to/from cpupools Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 47/48] xen/sched: disable scheduling when entering ACPI deep sleep states Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 48/48] xen/sched: add scheduling granularity enum Juergen Gross
2019-08-15 10:17 ` [Xen-devel] [PATCH v2 00/48] xen: add core scheduling support Sergey Dyasli
2019-09-05  6:22   ` Juergen Gross

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