On 8/18/17 4:50 PM, Dario Faggioli wrote:
@@ -474,6 +586,12 @@ static inline struct csched2_runqueue_data *c2rqd(const struct scheduler *ops,
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.
*
@@ -1515,7 +1633,16 @@ static void reset_credit(const struct scheduler *ops,
int cpu, s_time_t now,
* 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);
This is for accounting of credit. Why it willl impact the budget. Do you
intend to refer that
budget of current vcpu expired while doing calculation for credit ??
+ }
start_credit = svc->credit;
@@ -1571,27 +1698,35 @@ void burn_credits(struct csched2_runqueue_data *rqd,
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) )
{
+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 );
+ }
Just a bit confused. Have you seen this kind of scenario. Please can you
explain it.
Is this condition necessary.
+ /*
+ * 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;
+ }
"if we overran by more than tot_budget in previous run", make is more
clear..
+
+ /* 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)
@@ -1658,6 +2035,9 @@ csched2_alloc_vdata(const struct scheduler *ops, struct
vcpu *vc, void *dd)
}
svc->tickled_cpu = -1;
+
Rest, looks good to me.
Thanks
Anshul
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