* to a small value, and a fixed credit is added to everyone.
*/
+/*
+ * Utilization cap:
+ *
+ * Setting an pCPU utilization cap for a domain means the following:
+ *
+ * - a domain can have a cap, expressed in terms of % of physical CPU time.
+ * A domain that must not use more than 1/4 of _one_ physical CPU, will
+ * be given a cap of 25%; a domain that must not use more than 1+1/2 of
+ * physical CPU time, will be given a cap of 150%;
+ *
+ * - caps are per-domain (not per-vCPU). If a domain has only 1 vCPU, and
+ * a 40% cap, that one vCPU will use 40% of one pCPU. If a somain has 4
+ * vCPUs, and a 200% cap, the equivalent of 100% time on 2 pCPUs will be
+ * split among the v vCPUs. How much each of the vCPUs will actually get,
+ * during any given interval of time, is unspecified (as it depends on
+ * various aspects: workload, system load, etc.). For instance, it is
+ * possible that, during a given time interval, 2 vCPUs use 100% each,
+ * and the other two use nothing; while during another time interval,
+ * two vCPUs use 80%, one uses 10% and the other 30%; or that each use
+ * 50% (and so on and so forth).
+ *
+ * For implementing this, we use the following approach:
+ *
+ * - each domain is given a 'budget', an each domain has a timer, which
+ * replenishes the domain's budget periodically. The budget is the amount
+ * of time the vCPUs of the domain can use every 'period';
+ *
+ * - the period is CSCHED2_BDGT_REPL_PERIOD, and is the same for all domains
+ * (but each domain has its own timer; so the all are periodic by the same
+ * period, but replenishment of the budgets of the various domains, at
+ * periods boundaries, are not synchronous);
+ *
+ * - when vCPUs run, they consume budget. When they don't run, they don't
+ * consume budget. If there is no budget left for the domain, no vCPU of
+ * that domain can run. If a vCPU tries to run and finds that there is no
+ * budget, it blocks.
+ * At whatever time a vCPU wants to run, it must check the domain's budget,
+ * and if there is some, it can use it.
+ *
+ * - budget is replenished to the top of the capacity for the domain once
+ * per period. Even if there was some leftover budget from previous period,
+ * though, the budget after a replenishment will always be at most equal
+ * to the total capacify of the domain ('tot_budget');
+ *
+ * - when a budget replenishment occurs, if there are vCPUs that had been
+ * blocked because of lack of budget, they'll be unblocked, and they will
+ * (potentially) be able to run again.
+ *
+ * Finally, some even more implementation related detail:
+ *
+ * - budget is stored in a domain-wide pool. vCPUs of the domain that want
+ * to run go to such pool, and grub some. When they do so, the amount
+ * they grabbed is _immediately_ removed from the pool. This happens in
+ * vcpu_grab_budget();
+ *
+ * - when vCPUs stop running, if they've not consumed all the budget they
+ * took, the leftover is put back in the pool. This happens in
+ * vcpu_return_budget();
+ *
+ * - the above means that a vCPU can find out that there is no budget and
+ * block, not only if the cap has actually been reached (for this period),
+ * but also if some other vCPUs, in order to run, have grabbed a certain
+ * quota of budget, no matter whether they've already used it all or not.
+ * A vCPU blocking because (any form of) lack of budget is said to be
+ * "parked", and such blocking happens in park_vcpu();
+ *
+ * - when a vCPU stops running, and puts back some budget in the domain pool,
+ * we need to check whether there is someone which has been parked and that
+ * can be unparked. This happens in unpark_parked_vcpus(), called from
+ * csched2_context_saved();
+ *
+ * - of course, unparking happens also as a consequence of the domain's budget
+ * being replenished by the periodic timer. This also occurs by means of
+ * calling csched2_context_saved() (but from replenish_domain_budget());
+ *
+ * - parked vCPUs of a domain are kept in a (per-domain) list, called
+ * 'parked_vcpus'). Manipulation of the list and of the domain-wide budget
+ * pool, must occur only when holding the 'budget_lock'.
+ */
+
/*
* Locking:
*
* runqueue each cpu is;
* + serializes the operation of changing the weights of domains;
*
+ * - Budget lock
+ * + it is per-domain;
+ * + protects, in domains that have an utilization cap;
+ * * manipulation of the total budget of the domain (as it is shared
+ * among all vCPUs of the domain),
+ * * manipulation of the list of vCPUs that are blocked waiting for
+ * some budget to be available.
+ *
* - Type:
* + runqueue locks are 'regular' spinlocks;
* + the private scheduler lock can be an rwlock. In fact, data
* it protects is modified only during initialization, cpupool
* manipulation and when changing weights, and read in all
- * other cases (e.g., during load balancing).
+ * other cases (e.g., during load balancing);
+ * + budget locks are 'regular' spinlocks.
*
* Ordering:
* + tylock must be used when wanting to take a runqueue lock,
* if we already hold another one;
* + if taking both a runqueue lock and the private scheduler
- * lock is, the latter must always be taken for first.
+ * lock is, the latter must always be taken for first;
+ * + if taking both a runqueue lock and a budget lock, the former
+ * must always be taken for first.
*/
/*
#define CSCHED2_CREDIT_RESET 0
/* Max timer: Maximum time a guest can be run for. */
#define CSCHED2_MAX_TIMER CSCHED2_CREDIT_INIT
+/* Period of the cap replenishment timer. */
+#define CSCHED2_BDGT_REPL_PERIOD ((opt_cap_period)*MILLISECS(1))
/*
* Flags
integer_param("credit2_balance_under", opt_underload_balance_tolerance);
static int __read_mostly opt_overload_balance_tolerance = -3;
integer_param("credit2_balance_over", opt_overload_balance_tolerance);
+/*
+ * Domains subject to a cap receive a replenishment of their runtime budget
+ * once every opt_cap_period interval. Default is 10 ms. The amount of budget
+ * they receive depends on their cap. For instance, a domain with a 50% cap
+ * will receive 50% of 10 ms, so 5 ms.
+ */
+static unsigned int __read_mostly opt_cap_period = 10; /* ms */
+integer_param("credit2_cap_period_ms", opt_cap_period);
/*
* Runqueue organization.
* Virtual CPU
*/
struct csched2_vcpu {
- struct list_head rqd_elem; /* On csched2_runqueue_data's svc list */
+ struct csched2_dom *sdom; /* Up-pointer to domain */
+ struct vcpu *vcpu; /* Up-pointer, to vcpu */
struct csched2_runqueue_data *rqd; /* Up-pointer to the runqueue */
int credit; /* Current amount of credit */
unsigned int weight; /* Weight of this vcpu */
unsigned int residual; /* Reminder of div(max_weight/weight) */
unsigned flags; /* Status flags (16 bits would be ok, */
+ s_time_t budget; /* Current budget (if domains has cap) */
/* but clear_bit() does not like that) */
s_time_t start_time; /* Time we were scheduled (for credit) */
s_time_t avgload; /* Decaying queue load */
struct list_head runq_elem; /* On the runqueue (rqd->runq) */
- struct csched2_dom *sdom; /* Up-pointer to domain */
- struct vcpu *vcpu; /* Up-pointer, to vcpu */
-
+ struct list_head parked_elem; /* On the parked_vcpus list */
+ struct list_head rqd_elem; /* On csched2_runqueue_data's svc list */
struct csched2_runqueue_data *migrate_rqd; /* Pre-determined migr. target */
int tickled_cpu; /* Cpu that will pick us (-1 if none) */
};
* Domain
*/
struct csched2_dom {
- struct list_head sdom_elem; /* On csched2_runqueue_data's sdom list */
struct domain *dom; /* Up-pointer to domain */
+
+ spinlock_t budget_lock; /* Serialized budget calculations */
+ s_time_t tot_budget; /* Total amount of budget */
+ s_time_t budget; /* Currently available budget */
+
+ struct timer *repl_timer; /* Timer for periodic replenishment of budget */
+ s_time_t next_repl; /* Time at which next replenishment occurs */
+ struct list_head parked_vcpus; /* List of CPUs waiting for budget */
+
+ struct list_head sdom_elem; /* On csched2_runqueue_data's sdom list */
uint16_t weight; /* User specified weight */
+ uint16_t cap; /* User specified cap */
uint16_t nr_vcpus; /* Number of vcpus of this domain */
};
return &csched2_priv(ops)->rqd[c2r(cpu)];
}
+/* Does the domain of this vCPU have a cap? */
+static inline bool has_cap(const struct csched2_vcpu *svc)
+{
+ return svc->budget != STIME_MAX;
+}
+
/*
* Hyperthreading (SMT) support.
*
* that the credit it has spent so far get accounted.
*/
if ( svc->vcpu == curr_on_cpu(svc_cpu) )
+ {
burn_credits(rqd, svc, now);
+ /*
+ * And, similarly, in case it has run out of budget, as a
+ * consequence of this round of accounting, we also must inform
+ * its pCPU that it's time to park it, and pick up someone else.
+ */
+ if ( unlikely(svc->budget <= 0) )
+ tickle_cpu(svc_cpu, rqd);
+ }
start_credit = svc->credit;
delta = now - svc->start_time;
- if ( likely(delta > 0) )
- {
- SCHED_STAT_CRANK(burn_credits_t2c);
- t2c_update(rqd, delta, svc);
- svc->start_time = now;
- }
- else if ( delta < 0 )
+ if ( unlikely(delta <= 0) )
{
- d2printk("WARNING: %s: Time went backwards? now %"PRI_stime" start_time %"PRI_stime"\n",
- __func__, now, svc->start_time);
+ if ( unlikely(delta < 0) )
+ d2printk("WARNING: %s: Time went backwards? now %"PRI_stime
+ " start_time %"PRI_stime"\n", __func__, now,
+ svc->start_time);
+ goto out;
}
+ SCHED_STAT_CRANK(burn_credits_t2c);
+ t2c_update(rqd, delta, svc);
+
+ if ( has_cap(svc) )
+ svc->budget -= delta;
+
+ svc->start_time = now;
+
+ out:
if ( unlikely(tb_init_done) )
{
struct {
unsigned vcpu:16, dom:16;
- int credit, delta;
+ int credit, budget;
+ int delta;
} d;
d.dom = svc->vcpu->domain->domain_id;
d.vcpu = svc->vcpu->vcpu_id;
d.credit = svc->credit;
+ d.budget = has_cap(svc) ? svc->budget : INT_MIN;
d.delta = delta;
__trace_var(TRC_CSCHED2_CREDIT_BURN, 1,
sizeof(d),
}
}
+/*
+ * Budget-related code.
+ */
+
+static void park_vcpu(struct csched2_vcpu *svc)
+{
+ struct vcpu *v = svc->vcpu;
+
+ ASSERT(spin_is_locked(&svc->sdom->budget_lock));
+
+ /*
+ * It was impossible to find budget for this vCPU, so it has to be
+ * "parked". This implies it is not runnable, so we mark it as such in
+ * its pause_flags. If the vCPU is currently scheduled (which means we
+ * are here after being called from within csched_schedule()), flagging
+ * is enough, as we'll choose someone else, and then context_saved()
+ * will take care of updating the load properly.
+ *
+ * If, OTOH, the vCPU is sitting in the runqueue (which means we are here
+ * after being called from within runq_candidate()), we must go all the
+ * way down to taking it out of there, and updating the load accordingly.
+ *
+ * In both cases, we also add it to the list of parked vCPUs of the domain.
+ */
+ __set_bit(_VPF_parked, &v->pause_flags);
+ if ( vcpu_on_runq(svc) )
+ {
+ runq_remove(svc);
+ update_load(svc->sdom->dom->cpupool->sched, svc->rqd, svc, -1, NOW());
+ }
+ list_add(&svc->parked_elem, &svc->sdom->parked_vcpus);
+}
+
+static bool vcpu_grab_budget(struct csched2_vcpu *svc)
+{
+ struct csched2_dom *sdom = svc->sdom;
+ unsigned int cpu = svc->vcpu->processor;
+
+ ASSERT(spin_is_locked(per_cpu(schedule_data, cpu).schedule_lock));
+
+ if ( svc->budget > 0 )
+ return true;
+
+ /* budget_lock nests inside runqueue lock. */
+ spin_lock(&sdom->budget_lock);
+
+ /*
+ * Here, svc->budget is <= 0 (as, if it was > 0, we'd have taken the if
+ * above!). That basically means the vCPU has overrun a bit --because of
+ * various reasons-- and we want to take that into account. With the +=,
+ * we are actually subtracting the amount of budget the vCPU has
+ * overconsumed, from the total domain budget.
+ */
+ sdom->budget += svc->budget;
+
+ if ( sdom->budget > 0 )
+ {
+ /*
+ * NB: we give the whole remaining budget a domain has, to the first
+ * vCPU that comes here and asks for it. This means that, in a domain
+ * with a cap, only 1 vCPU is able to run, at any given time.
+ * /THIS IS GOING TO CHANGE/ in subsequent patches, toward something
+ * that allows much better fairness and parallelism. Proceeding in
+ * two steps, is for making things easy to understand, when looking
+ * at the signle commits.
+ */
+ svc->budget = sdom->budget;
+ sdom->budget = 0;
+ }
+ else
+ {
+ svc->budget = 0;
+ park_vcpu(svc);
+ }
+
+ spin_unlock(&sdom->budget_lock);
+
+ return svc->budget > 0;
+}
+
+static void
+vcpu_return_budget(struct csched2_vcpu *svc, struct list_head *parked)
+{
+ struct csched2_dom *sdom = svc->sdom;
+ unsigned int cpu = svc->vcpu->processor;
+
+ ASSERT(spin_is_locked(per_cpu(schedule_data, cpu).schedule_lock));
+ ASSERT(list_empty(parked));
+
+ /* budget_lock nests inside runqueue lock. */
+ spin_lock(&sdom->budget_lock);
+
+ /*
+ * The vCPU is stopping running (e.g., because it's blocking, or it has
+ * been preempted). If it hasn't consumed all the budget it got when,
+ * starting to run, put that remaining amount back in the domain's budget
+ * pool.
+ */
+ sdom->budget += svc->budget;
+ svc->budget = 0;
+
+ /*
+ * Making budget available again to the domain means that parked vCPUs
+ * may be unparked and run. They are, if any, in the domain's parked_vcpus
+ * list, so we want to go through that and unpark them (so they can try
+ * to get some budget).
+ *
+ * Touching the list requires the budget_lock, which we hold. Let's
+ * therefore put everyone in that list in another, temporary list, which
+ * then the caller will traverse, unparking the vCPUs it finds there.
+ *
+ * In fact, we can't do the actual unparking here, because that requires
+ * taking the runqueue lock of the vCPUs being unparked, and we can't
+ * take any runqueue locks while we hold a budget_lock.
+ */
+ if ( sdom->budget > 0 )
+ list_splice_init(&sdom->parked_vcpus, parked);
+
+ spin_unlock(&sdom->budget_lock);
+}
+
+static void
+unpark_parked_vcpus(const struct scheduler *ops, struct list_head *vcpus)
+{
+ struct csched2_vcpu *svc, *tmp;
+ spinlock_t *lock;
+
+ list_for_each_entry_safe(svc, tmp, vcpus, parked_elem)
+ {
+ unsigned long flags;
+ s_time_t now;
+
+ lock = vcpu_schedule_lock_irqsave(svc->vcpu, &flags);
+
+ __clear_bit(_VPF_parked, &svc->vcpu->pause_flags);
+ if ( unlikely(svc->flags & CSFLAG_scheduled) )
+ {
+ /*
+ * We end here if a budget replenishment arrived between
+ * csched2_schedule() (and, in particular, after a call to
+ * vcpu_grab_budget() that returned false), and
+ * context_saved(). By setting __CSFLAG_delayed_runq_add,
+ * we tell context_saved() to put the vCPU back in the
+ * runqueue, from where it will compete with the others
+ * for the newly replenished budget.
+ */
+ ASSERT( svc->rqd != NULL );
+ ASSERT( c2rqd(ops, svc->vcpu->processor) == svc->rqd );
+ __set_bit(__CSFLAG_delayed_runq_add, &svc->flags);
+ }
+ else if ( vcpu_runnable(svc->vcpu) )
+ {
+ /*
+ * The vCPU should go back to the runqueue, and compete for
+ * the newly replenished budget, but only if it is actually
+ * runnable (and was therefore offline only because of the
+ * lack of budget).
+ */
+ now = NOW();
+ update_load(ops, svc->rqd, svc, 1, now);
+ runq_insert(ops, svc);
+ runq_tickle(ops, svc, now);
+ }
+ list_del_init(&svc->parked_elem);
+
+ vcpu_schedule_unlock_irqrestore(lock, flags, svc->vcpu);
+ }
+}
+
+static inline void do_replenish(struct csched2_dom *sdom)
+{
+ sdom->next_repl += CSCHED2_BDGT_REPL_PERIOD;
+ sdom->budget += sdom->tot_budget;
+}
+
+static void replenish_domain_budget(void* data)
+{
+ struct csched2_dom *sdom = data;
+ unsigned long flags;
+ s_time_t now;
+ LIST_HEAD(parked);
+
+ spin_lock_irqsave(&sdom->budget_lock, flags);
+
+ now = NOW();
+
+ /*
+ * Let's do the replenishment. Note, though, that a domain may overrun,
+ * which means the budget would have gone below 0 (reasons may be system
+ * overbooking, accounting issues, etc.). It also may happen that we are
+ * handling the replenishment (much) later than we should (reasons may
+ * again be overbooking, or issues with timers).
+ *
+ * Even in cases of overrun or delay, however, we expect that in 99% of
+ * cases, doing just one replenishment will be good enough for being able
+ * to unpark the vCPUs that are waiting for some budget.
+ */
+ do_replenish(sdom);
+
+ /*
+ * And now, the special cases:
+ * 1) if we are late enough to have skipped (at least) one full period,
+ * what we must do is doing more replenishments. Note that, however,
+ * every time we add tot_budget to the budget, we also move next_repl
+ * away by CSCHED2_BDGT_REPL_PERIOD, to make sure the cap is always
+ * respected.
+ */
+ if ( unlikely(sdom->next_repl <= now) )
+ {
+ do
+ do_replenish(sdom);
+ while ( sdom->next_repl <= now );
+ }
+ /*
+ * 2) if we overrun by more than tot_budget, then budget+tot_budget is
+ * still < 0, which means that we can't unpark the vCPUs. Let's bail,
+ * and wait for future replenishments.
+ */
+ if ( unlikely(sdom->budget <= 0) )
+ {
+ spin_unlock_irqrestore(&sdom->budget_lock, flags);
+ goto out;
+ }
+
+ /* Since we do more replenishments, make sure we didn't overshot. */
+ sdom->budget = min(sdom->budget, sdom->tot_budget);
+
+ /*
+ * As above, let's prepare the temporary list, out of the domain's
+ * parked_vcpus list, now that we hold the budget_lock. Then, drop such
+ * lock, and pass the list to the unparking function.
+ */
+ list_splice_init(&sdom->parked_vcpus, &parked);
+
+ spin_unlock_irqrestore(&sdom->budget_lock, flags);
+
+ unpark_parked_vcpus(sdom->dom->cpupool->sched, &parked);
+
+ out:
+ set_timer(sdom->repl_timer, sdom->next_repl);
+}
+
#ifndef NDEBUG
static inline void
csched2_vcpu_check(struct vcpu *vc)
}
svc->tickled_cpu = -1;
+ svc->budget = STIME_MAX;
+ INIT_LIST_HEAD(&svc->parked_elem);
+
SCHED_STAT_CRANK(vcpu_alloc);
return svc;
struct csched2_vcpu * const svc = csched2_vcpu(vc);
spinlock_t *lock = vcpu_schedule_lock_irq(vc);
s_time_t now = NOW();
+ LIST_HEAD(were_parked);
BUG_ON( !is_idle_vcpu(vc) && svc->rqd != c2rqd(ops, vc->processor));
ASSERT(is_idle_vcpu(vc) || svc->rqd == c2rqd(ops, vc->processor));
/* This vcpu is now eligible to be put on the runqueue again */
__clear_bit(__CSFLAG_scheduled, &svc->flags);
+ if ( unlikely(has_cap(svc) && svc->budget > 0) )
+ vcpu_return_budget(svc, &were_parked);
+
/* If someone wants it on the runqueue, put it there. */
/*
* NB: We can get rid of CSFLAG_scheduled by checking for
update_load(ops, svc->rqd, svc, -1, now);
vcpu_schedule_unlock_irq(lock, vc);
+
+ unpark_parked_vcpus(ops, &were_parked);
}
#define MAX_LOAD (STIME_MAX)
if ( sdom == NULL )
return NULL;
- /* Initialize credit and weight */
+ sdom->repl_timer = xzalloc(struct timer);
+ if ( sdom->repl_timer == NULL )
+ {
+ xfree(sdom);
+ return NULL;
+ }
+
+ /* Initialize credit, cap and weight */
INIT_LIST_HEAD(&sdom->sdom_elem);
sdom->dom = dom;
sdom->weight = CSCHED2_DEFAULT_WEIGHT;
+ sdom->cap = 0U;
sdom->nr_vcpus = 0;
+ init_timer(sdom->repl_timer, replenish_domain_budget, sdom,
+ cpumask_any(cpupool_domain_cpumask(dom)));
+ spin_lock_init(&sdom->budget_lock);
+ INIT_LIST_HEAD(&sdom->parked_vcpus);
+
write_lock_irqsave(&prv->lock, flags);
list_add_tail(&sdom->sdom_elem, &csched2_priv(ops)->sdom);
write_lock_irqsave(&prv->lock, flags);
+ kill_timer(sdom->repl_timer);
+ xfree(sdom->repl_timer);
+
list_del_init(&sdom->sdom_elem);
write_unlock_irqrestore(&prv->lock, flags);
return -1;
/* General algorithm:
- * 1) Run until snext's credit will be 0
+ * 1) Run until snext's credit will be 0.
* 2) But if someone is waiting, run until snext's credit is equal
- * to his
- * 3) But never run longer than MAX_TIMER or shorter than MIN_TIMER or
- * the ratelimit time.
+ * to his.
+ * 3) But, if we are capped, never run more than our budget.
+ * 4) And never run longer than MAX_TIMER or shorter than MIN_TIMER or
+ * the ratelimit time.
*/
/* Calculate mintime */
min_time = ratelimit_min;
}
- /* 1) Basic time: Run until credit is 0. */
+ /* 1) Run until snext's credit will be 0. */
rt_credit = snext->credit;
- /* 2) If there's someone waiting whose credit is positive,
- * run until your credit ~= his */
+ /*
+ * 2) If there's someone waiting whose credit is positive,
+ * run until your credit ~= his.
+ */
if ( ! list_empty(runq) )
{
struct csched2_vcpu *swait = runq_elem(runq->next);
* credit values of MIN,MAX per vcpu, since each vcpu burns credit
* at a different rate.
*/
- if (rt_credit > 0)
+ if ( rt_credit > 0 )
time = c2t(rqd, rt_credit, snext);
else
time = 0;
- /* 3) But never run longer than MAX_TIMER or less than MIN_TIMER or
- * the rate_limit time. */
- if ( time < min_time)
+ /*
+ * 3) But, if capped, never run more than our budget.
+ */
+ if ( has_cap(snext) )
+ time = snext->budget < time ? snext->budget : time;
+
+ /*
+ * 4) And never run longer than MAX_TIMER or less than MIN_TIMER or
+ * the rate_limit time.
+ */
+ if ( time < min_time )
{
time = min_time;
SCHED_STAT_CRANK(runtime_min_timer);
int cpu, s_time_t now,
unsigned int *skipped)
{
- struct list_head *iter;
+ struct list_head *iter, *temp;
struct csched2_vcpu *snext = NULL;
struct csched2_private *prv = csched2_priv(per_cpu(scheduler, cpu));
bool yield = false, soft_aff_preempt = false;
snext = csched2_vcpu(idle_vcpu[cpu]);
check_runq:
- list_for_each( iter, &rqd->runq )
+ list_for_each_safe( iter, temp, &rqd->runq )
{
struct csched2_vcpu * svc = list_entry(iter, struct csched2_vcpu, runq_elem);
}
/*
- * If the next one on the list has more credit than current
- * (or idle, if current is not runnable), or if current is
- * yielding, choose it.
+ * If the one in the runqueue has more credit than current (or idle,
+ * if current is not runnable), or if current is yielding, and also
+ * if the one in runqueue either is not capped, or is capped but has
+ * some budget, then choose it.
*/
- if ( yield || svc->credit > snext->credit )
+ if ( (yield || svc->credit > snext->credit) &&
+ (!has_cap(svc) || vcpu_grab_budget(svc)) )
snext = svc;
/* In any case, if we got this far, break. */
if ( unlikely(snext->tickled_cpu != -1 && snext->tickled_cpu != cpu) )
SCHED_STAT_CRANK(tickled_cpu_overridden);
+ /*
+ * If snext is from a capped domain, it must have budget (or it
+ * wouldn't have been in the runq). If it is not, it'd be STIME_MAX,
+ * which still is >= 0.
+ */
+ ASSERT(snext->budget >= 0);
+
return snext;
}
(unsigned char *)&d);
}
- /* Update credits */
+ /* Update credits (and budget, if necessary). */
burn_credits(rqd, scurr, now);
+ /*
+ * Below 0, means that we are capped and we have overrun our budget.
+ * Let's try to get some more but, if we fail (e.g., because of the
+ * other running vcpus), we will be parked.
+ */
+ if ( unlikely(scurr->budget <= 0) )
+ vcpu_grab_budget(scurr);
+
/*
* Select next runnable local VCPU (ie top of local runq).
*
printk(" credit=%" PRIi32" [w=%u]", svc->credit, svc->weight);
+ if ( has_cap(svc) )
+ printk(" budget=%"PRI_stime, svc->budget);
+
printk(" load=%"PRI_stime" (~%"PRI_stime"%%)", svc->avgload,
(svc->avgload * 100) >> prv->load_precision_shift);
sdom = list_entry(iter_sdom, struct csched2_dom, sdom_elem);
- printk("\tDomain: %d w %d v %d\n",
+ printk("\tDomain: %d w %d c %u v %d\n",
sdom->dom->domain_id,
sdom->weight,
+ sdom->cap,
sdom->nr_vcpus);
for_each_vcpu( sdom->dom, v )
XENLOG_INFO " load_window_shift: %d\n"
XENLOG_INFO " underload_balance_tolerance: %d\n"
XENLOG_INFO " overload_balance_tolerance: %d\n"
- XENLOG_INFO " runqueues arrangement: %s\n",
+ XENLOG_INFO " runqueues arrangement: %s\n"
+ XENLOG_INFO " cap enforcement granularity: %dms\n",
opt_load_precision_shift,
opt_load_window_shift,
opt_underload_balance_tolerance,
opt_overload_balance_tolerance,
- opt_runqueue_str[opt_runqueue]);
+ opt_runqueue_str[opt_runqueue],
+ opt_cap_period);
if ( opt_load_precision_shift < LOADAVG_PRECISION_SHIFT_MIN )
{
printk(XENLOG_INFO "load tracking window length %llu ns\n",
1ULL << opt_load_window_shift);
+ if ( CSCHED2_BDGT_REPL_PERIOD < CSCHED2_MIN_TIMER )
+ {
+ printk("WARNING: %s: opt_cap_period %d too small, resetting\n",
+ __func__, opt_cap_period);
+ opt_cap_period = 10; /* ms */
+ }
+
/*
* Basically no CPU information is available at this point; just
* set up basic structures, and a callback when the CPU info is
projects / xen.git / commitdiff