By applying this patch, the credit scheduler balances credits of each
active vcpu of a domain.
Best regards,
Naoki Nishiguchi
diff -r a00eb6595d3c xen/common/sched_credit.c
--- a/xen/common/sched_credit.c Sat Nov 29 09:07:52 2008 +0000
+++ b/xen/common/sched_credit.c Fri Dec 05 18:16:34 2008 +0900
@@ -835,7 +835,8 @@ csched_acct(void)
int credit_balance;
int credit_xtra;
int credit;
-
+ int64_t credit_sum;
+ int credit_average;
spin_lock_irqsave(&csched_priv.lock, flags);
@@ -872,6 +873,18 @@ csched_acct(void)
BUG_ON( sdom->active_vcpu_count == 0 );
BUG_ON( sdom->weight == 0 );
BUG_ON( sdom->weight > weight_left );
+
+ /* Compute the average of active VCPUs. */
+ credit_sum = 0;
+ list_for_each_safe( iter_vcpu, next_vcpu, &sdom->active_vcpu )
+ {
+ svc = list_entry(iter_vcpu, struct csched_vcpu, active_vcpu_elem);
+ BUG_ON( sdom != svc->sdom );
+
+ credit_sum += atomic_read(&svc->credit);
+ }
+ credit_average = ( credit_sum + (sdom->active_vcpu_count - 1)
+ ) / sdom->active_vcpu_count;
weight_left -= sdom->weight;
@@ -944,8 +957,9 @@ csched_acct(void)
svc = list_entry(iter_vcpu, struct csched_vcpu, active_vcpu_elem);
BUG_ON( sdom != svc->sdom );
- /* Increment credit */
- atomic_add(credit_fair, &svc->credit);
+ /* Balance and increment credit */
+ credit = atomic_read(&svc->credit);
+ atomic_add(credit_average - credit + credit_fair, &svc->credit);
credit = atomic_read(&svc->credit);
/*
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