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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v2 45/48] xen/sched: support differing granularity in schedule_cpu_[add/rm]()
With core scheduling active schedule_cpu_[add/rm]() has to cope with
different scheduling granularity: a cpu not in any cpupool is subject
to granularity 1 (cpu scheduling), while a cpu in a cpupool might be
in a scheduling resource with more than one cpu.
Handle that by having arrays of old/new pdata and vdata and loop over
those where appropriate.
Additionally the scheduling resource(s) must either be merged or
split.
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
xen/common/cpupool.c | 18 ++--
xen/common/schedule.c | 226 +++++++++++++++++++++++++++++++++++++++++++-------
2 files changed, 204 insertions(+), 40 deletions(-)
diff --git a/xen/common/cpupool.c b/xen/common/cpupool.c
index 5d5c8d5430..41d594dace 100644
--- a/xen/common/cpupool.c
+++ b/xen/common/cpupool.c
@@ -535,6 +535,7 @@ static void cpupool_cpu_remove(unsigned int cpu)
ret = cpupool_unassign_cpu_epilogue(cpupool0);
BUG_ON(ret);
}
+ cpumask_clear_cpu(cpu, &cpupool_free_cpus);
}
/*
@@ -584,20 +585,19 @@ static void cpupool_cpu_remove_forced(unsigned int cpu)
struct cpupool **c;
int ret;
- if ( cpumask_test_cpu(cpu, &cpupool_free_cpus) )
- cpumask_clear_cpu(cpu, &cpupool_free_cpus);
- else
+ for_each_cpupool ( c )
{
- for_each_cpupool(c)
+ if ( cpumask_test_cpu(cpu, (*c)->cpu_valid) )
{
- if ( cpumask_test_cpu(cpu, (*c)->cpu_valid) )
- {
- ret = cpupool_unassign_cpu(*c, cpu);
- BUG_ON(ret);
- }
+ ret = cpupool_unassign_cpu_prologue(*c, cpu);
+ BUG_ON(ret);
+ ret = cpupool_unassign_cpu_epilogue(*c);
+ BUG_ON(ret);
}
}
+ cpumask_clear_cpu(cpu, &cpupool_free_cpus);
+
rcu_read_lock(&sched_res_rculock);
sched_rm_cpu(cpu);
rcu_read_unlock(&sched_res_rculock);
diff --git a/xen/common/schedule.c b/xen/common/schedule.c
index 948fe1b838..a4555fd0fa 100644
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -407,26 +407,29 @@ static void sched_unit_add_vcpu(struct sched_unit *unit,
struct vcpu *v)
unit->runstate_cnt[v->runstate.state]++;
}
-static struct sched_unit *sched_alloc_unit(struct vcpu *v)
+static struct sched_unit *sched_alloc_unit_mem(void)
{
- struct sched_unit *unit, **prev_unit;
- struct domain *d = v->domain;
- unsigned int gran = d->cpupool ? d->cpupool->granularity : 1;
+ struct sched_unit *unit;
- for_each_sched_unit ( d, unit )
- if ( unit->vcpu_list->vcpu_id / gran == v->vcpu_id / gran )
- break;
+ unit = xzalloc(struct sched_unit);
+ if ( !unit )
+ return NULL;
- if ( unit )
+ if ( !zalloc_cpumask_var(&unit->cpu_hard_affinity) ||
+ !zalloc_cpumask_var(&unit->cpu_hard_affinity_saved) ||
+ !zalloc_cpumask_var(&unit->cpu_soft_affinity) )
{
- sched_unit_add_vcpu(unit, v);
- return unit;
+ sched_free_unit_mem(unit);
+ unit = NULL;
}
- if ( (unit = xzalloc(struct sched_unit)) == NULL )
- return NULL;
+ return unit;
+}
+
+static void sched_domain_insert_unit(struct sched_unit *unit, struct domain *d)
+{
+ struct sched_unit **prev_unit;
- sched_unit_add_vcpu(unit, v);
unit->domain = d;
for ( prev_unit = &d->sched_unit_list; *prev_unit;
@@ -437,17 +440,31 @@ static struct sched_unit *sched_alloc_unit(struct vcpu *v)
unit->next_in_list = *prev_unit;
*prev_unit = unit;
+}
- if ( !zalloc_cpumask_var(&unit->cpu_hard_affinity) ||
- !zalloc_cpumask_var(&unit->cpu_hard_affinity_saved) ||
- !zalloc_cpumask_var(&unit->cpu_soft_affinity) )
- goto fail;
+static struct sched_unit *sched_alloc_unit(struct vcpu *v)
+{
+ struct sched_unit *unit;
+ struct domain *d = v->domain;
+ unsigned int gran = d->cpupool ? d->cpupool->granularity : 1;
- return unit;
+ for_each_sched_unit ( d, unit )
+ if ( unit->vcpu_list->vcpu_id / gran == v->vcpu_id / gran )
+ break;
- fail:
- sched_free_unit(unit, v);
- return NULL;
+ if ( unit )
+ {
+ sched_unit_add_vcpu(unit, v);
+ return unit;
+ }
+
+ if ( (unit = sched_alloc_unit_mem()) == NULL )
+ return NULL;
+
+ sched_unit_add_vcpu(unit, v);
+ sched_domain_insert_unit(unit, d);
+
+ return unit;
}
static unsigned int sched_select_initial_cpu(const struct vcpu *v)
@@ -2370,18 +2387,28 @@ static void poll_timer_fn(void *data)
vcpu_unblock(v);
}
-static int cpu_schedule_up(unsigned int cpu)
+static struct sched_resource *sched_alloc_res(void)
{
struct sched_resource *sd;
sd = xzalloc(struct sched_resource);
if ( sd == NULL )
- return -ENOMEM;
+ return NULL;
if ( !zalloc_cpumask_var(&sd->cpus) )
{
xfree(sd);
- return -ENOMEM;
+ return NULL;
}
+ return sd;
+}
+
+static int cpu_schedule_up(unsigned int cpu)
+{
+ struct sched_resource *sd;
+
+ sd = sched_alloc_res();
+ if ( sd == NULL )
+ return -ENOMEM;
sd->processor = cpu;
cpumask_copy(sd->cpus, cpumask_of(cpu));
@@ -2431,6 +2458,8 @@ static void sched_res_free(struct rcu_head *head)
struct sched_resource *sd = container_of(head, struct sched_resource, rcu);
free_cpumask_var(sd->cpus);
+ if ( sd->sched_unit_idle )
+ sched_free_unit_mem(sd->sched_unit_idle);
xfree(sd);
}
@@ -2445,6 +2474,8 @@ static void cpu_schedule_down(unsigned int cpu)
kill_timer(&sd->s_timer);
set_sched_res(cpu, NULL);
+ /* Keep idle unit. */
+ sd->sched_unit_idle = NULL;
call_rcu(&sd->rcu, sched_res_free);
rcu_read_unlock(&sched_res_rculock);
@@ -2524,6 +2555,30 @@ static struct notifier_block cpu_schedule_nfb = {
.notifier_call = cpu_schedule_callback
};
+static const cpumask_t *sched_get_opt_cpumask(enum sched_gran opt,
+ unsigned int cpu)
+{
+ const cpumask_t *mask;
+
+ switch ( opt )
+ {
+ case SCHED_GRAN_cpu:
+ mask = cpumask_of(cpu);
+ break;
+ case SCHED_GRAN_core:
+ mask = per_cpu(cpu_sibling_mask, cpu);
+ break;
+ case SCHED_GRAN_socket:
+ mask = per_cpu(cpu_core_mask, cpu);
+ break;
+ default:
+ ASSERT_UNREACHABLE();
+ return NULL;
+ }
+
+ return mask;
+}
+
/* Initialise the data structures. */
void __init scheduler_init(void)
{
@@ -2682,6 +2737,46 @@ int schedule_cpu_add(unsigned int cpu, struct cpupool *c)
*/
old_lock = pcpu_schedule_lock_irqsave(cpu, &flags);
+ if ( c->granularity > 1 )
+ {
+ const cpumask_t *mask;
+ unsigned int cpu_iter, idx = 0;
+ struct sched_unit *old_unit, *master_unit;
+ struct sched_resource *sd_old;
+
+ /*
+ * We need to merge multiple idle_vcpu units and sched_resource structs
+ * into one. As the free cpus all share the same lock we are fine doing
+ * that now. The worst which could happen would be someone waiting for
+ * the lock, thus dereferencing sched_res->schedule_lock. This is the
+ * reason we are freeing struct sched_res via call_rcu() to avoid the
+ * lock pointer suddenly disappearing.
+ */
+ mask = sched_get_opt_cpumask(c->opt_granularity, cpu);
+ master_unit = idle_vcpu[cpu]->sched_unit;
+
+ for_each_cpu ( cpu_iter, mask )
+ {
+ if ( idx )
+ cpumask_clear_cpu(cpu_iter, sched_res_mask);
+
+ per_cpu(sched_res_idx, cpu_iter) = idx++;
+
+ if ( cpu == cpu_iter )
+ continue;
+
+ old_unit = idle_vcpu[cpu_iter]->sched_unit;
+ sd_old = get_sched_res(cpu_iter);
+ kill_timer(&sd_old->s_timer);
+ idle_vcpu[cpu_iter]->sched_unit = master_unit;
+ master_unit->runstate_cnt[RUNSTATE_running]++;
+ set_sched_res(cpu_iter, sd);
+ cpumask_set_cpu(cpu_iter, sd->cpus);
+
+ call_rcu(&sd_old->rcu, sched_res_free);
+ }
+ }
+
new_lock = sched_switch_sched(new_ops, cpu, ppriv, vpriv);
sd->scheduler = new_ops;
@@ -2719,33 +2814,100 @@ out:
*/
int schedule_cpu_rm(unsigned int cpu)
{
- struct vcpu *idle;
void *ppriv_old, *vpriv_old;
- struct sched_resource *sd;
+ struct sched_resource *sd, **sd_new = NULL;
+ struct sched_unit *unit;
struct scheduler *old_ops;
spinlock_t *old_lock;
unsigned long flags;
+ int idx, ret = -ENOMEM;
+ unsigned int cpu_iter;
rcu_read_lock(&sched_res_rculock);
sd = get_sched_res(cpu);
old_ops = sd->scheduler;
+ if ( sd->granularity > 1 )
+ {
+ sd_new = xmalloc_array(struct sched_resource *, sd->granularity - 1);
+ if ( !sd_new )
+ goto out;
+ for ( idx = 0; idx < sd->granularity - 1; idx++ )
+ {
+ sd_new[idx] = sched_alloc_res();
+ if ( sd_new[idx] )
+ {
+ sd_new[idx]->sched_unit_idle = sched_alloc_unit_mem();
+ if ( !sd_new[idx]->sched_unit_idle )
+ {
+ sched_res_free(&sd_new[idx]->rcu);
+ sd_new[idx] = NULL;
+ }
+ }
+ if ( !sd_new[idx] )
+ {
+ for ( idx--; idx >= 0; idx-- )
+ sched_res_free(&sd_new[idx]->rcu);
+ goto out;
+ }
+ sd_new[idx]->curr = sd_new[idx]->sched_unit_idle;
+ sd_new[idx]->scheduler = &sched_idle_ops;
+ sd_new[idx]->granularity = 1;
+
+ /* We want the lock not to change when replacing the resource. */
+ sd_new[idx]->schedule_lock = sd->schedule_lock;
+ }
+ }
+
+ ret = 0;
ASSERT(sd->cpupool != NULL);
ASSERT(cpumask_test_cpu(cpu, &cpupool_free_cpus));
ASSERT(!cpumask_test_cpu(cpu, sd->cpupool->cpu_valid));
- idle = idle_vcpu[cpu];
-
sched_do_tick_suspend(old_ops, cpu);
/* See comment in schedule_cpu_add() regarding lock switching. */
old_lock = pcpu_schedule_lock_irqsave(cpu, &flags);
- vpriv_old = idle->sched_unit->priv;
+ vpriv_old = idle_vcpu[cpu]->sched_unit->priv;
ppriv_old = sd->sched_priv;
- idle->sched_unit->priv = NULL;
+ idx = 0;
+ for_each_cpu ( cpu_iter, sd->cpus )
+ {
+ per_cpu(sched_res_idx, cpu_iter) = 0;
+ if ( cpu_iter == cpu )
+ {
+ idle_vcpu[cpu_iter]->sched_unit->priv = NULL;
+ }
+ else
+ {
+ /* Initialize unit. */
+ unit = sd_new[idx]->sched_unit_idle;
+ unit->res = sd_new[idx];
+ unit->is_running = true;
+ sched_unit_add_vcpu(unit, idle_vcpu[cpu_iter]);
+ sched_domain_insert_unit(unit, idle_vcpu[cpu_iter]->domain);
+
+ /* Adjust cpu masks of resources (old and new). */
+ cpumask_clear_cpu(cpu_iter, sd->cpus);
+ cpumask_set_cpu(cpu_iter, sd_new[idx]->cpus);
+
+ /* Init timer. */
+ init_timer(&sd_new[idx]->s_timer, s_timer_fn, NULL, cpu_iter);
+
+ /* Last resource initializations and insert resource pointer. */
+ sd_new[idx]->processor = cpu_iter;
+ set_sched_res(cpu_iter, sd_new[idx]);
+
+ /* Last action: set the new lock pointer. */
+ smp_mb();
+ sd_new[idx]->schedule_lock = &sched_free_cpu_lock;
+
+ idx++;
+ }
+ }
sd->scheduler = &sched_idle_ops;
sd->sched_priv = NULL;
@@ -2763,9 +2925,11 @@ int schedule_cpu_rm(unsigned int cpu)
sd->granularity = 1;
sd->cpupool = NULL;
+out:
rcu_read_unlock(&sched_res_rculock);
+ xfree(sd_new);
- return 0;
+ return ret;
}
struct scheduler *scheduler_get_default(void)
--
2.16.4
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