diff -r 56032cbaf1e8 xen/common/sched_credit.c
--- a/xen/common/sched_credit.c	Thu Jan 22 10:43:50 2009 +0900
+++ b/xen/common/sched_credit.c	Thu Jan 22 13:06:24 2009 +0900
@@ -201,6 +201,7 @@ struct csched_vcpu {
     struct csched_dom *sdom;
     struct vcpu *vcpu;
     atomic_t credit;
+    int prev_credit;
     uint16_t flags;
     int16_t pri;
 #ifdef CSCHED_STATS
@@ -225,6 +226,7 @@ struct csched_dom {
     uint16_t active_vcpu_count;
     uint16_t weight;
     uint16_t cap;
+    uint16_t percent;
 };
 
 /*
@@ -239,6 +241,8 @@ struct csched_private {
     cpumask_t idlers;
     uint32_t weight;
     uint32_t credit;
+    uint32_t percent;
+    uint16_t total_percent;
     int credit_balance;
     uint32_t runq_sort;
     CSCHED_STATS_DEFINE()
@@ -503,6 +507,7 @@ __csched_vcpu_acct_start_locked(struct c
         {
             list_add(&sdom->active_sdom_elem, &csched_priv.active_sdom);
             csched_priv.weight += sdom->weight;
+            csched_priv.percent += sdom->percent;
         }
     }
 }
@@ -525,6 +530,7 @@ __csched_vcpu_acct_stop_locked(struct cs
         BUG_ON( csched_priv.weight < sdom->weight );
         list_del_init(&sdom->active_sdom_elem);
         csched_priv.weight -= sdom->weight;
+        csched_priv.percent -= sdom->percent;
     }
 }
 
@@ -579,6 +585,7 @@ csched_vcpu_init(struct vcpu *vc)
     svc->sdom = sdom;
     svc->vcpu = vc;
     atomic_set(&svc->credit, 0);
+    svc->prev_credit = 0;
     svc->flags = 0U;
     svc->pri = is_idle_domain(dom) ? CSCHED_PRI_IDLE : CSCHED_PRI_TS_UNDER;
     CSCHED_VCPU_STATS_RESET(svc);
@@ -712,25 +719,56 @@ csched_dom_cntl(
     {
         op->u.credit.weight = sdom->weight;
         op->u.credit.cap = sdom->cap;
+        op->u.credit.percent = sdom->percent;
     }
     else
     {
+        uint16_t weight = (uint16_t)~0U;
+
         ASSERT(op->cmd == XEN_DOMCTL_SCHEDOP_putinfo);
 
         spin_lock_irqsave(&csched_priv.lock, flags);
 
-        if ( op->u.credit.weight != 0 )
+        if ( (op->u.credit.weight != 0) &&
+             (sdom->percent == 0 || op->u.credit.percent == 0) )
+        {
+            weight = op->u.credit.weight;
+        }
+
+        if ( op->u.credit.cap != (uint16_t)~0U )
+            sdom->cap = op->u.credit.cap;
+
+        if ( (op->u.credit.percent != (uint16_t)~0U) &&
+             ((csched_priv.total_percent - sdom->percent +
+               op->u.credit.percent) <= 100 * csched_priv.ncpus) )
+        {
+            csched_priv.total_percent -= sdom->percent;
+            csched_priv.total_percent += op->u.credit.percent;
+
+            if ( !list_empty(&sdom->active_sdom_elem) )
+            {
+                csched_priv.percent -= sdom->percent;
+                csched_priv.percent += op->u.credit.percent;
+            }
+            sdom->percent = op->u.credit.percent;
+            if ( sdom->percent == 0 )
+            {
+                if ( sdom->weight == 0 )
+                    weight = CSCHED_DEFAULT_WEIGHT;
+            }
+            else
+                weight = 0;
+        }
+
+        if ( weight != (uint16_t)~0U )
         {
             if ( !list_empty(&sdom->active_sdom_elem) )
             {
                 csched_priv.weight -= sdom->weight;
-                csched_priv.weight += op->u.credit.weight;
+                csched_priv.weight += weight;
             }
-            sdom->weight = op->u.credit.weight;
-        }
-
-        if ( op->u.credit.cap != (uint16_t)~0U )
-            sdom->cap = op->u.credit.cap;
+            sdom->weight = weight;
+        }
 
         spin_unlock_irqrestore(&csched_priv.lock, flags);
     }
@@ -759,6 +797,7 @@ csched_dom_init(struct domain *dom)
     sdom->dom = dom;
     sdom->weight = CSCHED_DEFAULT_WEIGHT;
     sdom->cap = 0U;
+    sdom->percent = 0U;
     dom->sched_priv = sdom;
 
     return 0;
@@ -831,6 +870,7 @@ csched_acct(void)
     struct csched_dom *sdom;
     uint32_t credit_total;
     uint32_t weight_total;
+    uint32_t percent_credit;
     uint32_t weight_left;
     uint32_t credit_fair;
     uint32_t credit_peak;
@@ -857,6 +897,7 @@ csched_acct(void)
 
     weight_total = csched_priv.weight;
     credit_total = csched_priv.credit;
+    percent_credit = csched_priv.percent * CSCHED_CREDITS_PER_TSLICE / 100;
 
     /* Converge balance towards 0 when it drops negative */
     if ( csched_priv.credit_balance < 0 )
@@ -865,7 +906,7 @@ csched_acct(void)
         CSCHED_STAT_CRANK(acct_balance);
     }
 
-    if ( unlikely(weight_total == 0) )
+    if ( unlikely(weight_total == 0 && percent_credit == 0) )
     {
         csched_priv.credit_balance = 0;
         spin_unlock_irqrestore(&csched_priv.lock, flags);
@@ -880,22 +921,44 @@ csched_acct(void)
     credit_xtra = 0;
     credit_cap = 0U;
 
+    /* Firstly, subtract percent_credit from credit_total. */
+    if ( percent_credit != 0 )
+    {
+        credit_total -= percent_credit;
+        credit_balance += percent_credit;
+    }
+
+    /* Avoid 0 divide error */
+    if ( weight_total == 0 )
+        weight_total = 1;
+
     list_for_each_safe( iter_sdom, next_sdom, &csched_priv.active_sdom )
     {
         sdom = list_entry(iter_sdom, struct csched_dom, active_sdom_elem);
 
         BUG_ON( is_idle_domain(sdom->dom) );
         BUG_ON( sdom->active_vcpu_count == 0 );
-        BUG_ON( sdom->weight == 0 );
+        BUG_ON( sdom->weight == 0 && sdom->percent == 0 );
         BUG_ON( sdom->weight > weight_left );
 
-        /* Compute the average of active VCPUs. */
+        /*
+         * Compute the average of active VCPUs
+         * and adjust credit for comsumption too much.
+         */
         credit_sum = 0;
         list_for_each_safe( iter_vcpu, next_vcpu, &sdom->active_vcpu )
         {
+            int adjust;
+
             svc = list_entry(iter_vcpu, struct csched_vcpu, active_vcpu_elem);
             BUG_ON( sdom != svc->sdom );
 
+            credit = atomic_read(&svc->credit);
+            adjust = svc->prev_credit - credit - CSCHED_CREDITS_PER_TSLICE;
+            if ( adjust > 0 )
+            {
+                atomic_add(adjust, &svc->credit);
+            }
             credit_sum += atomic_read(&svc->credit);
         }
         credit_average = ( credit_sum + (sdom->active_vcpu_count - 1)
@@ -934,7 +997,9 @@ csched_acct(void)
 
         if ( credit_fair < credit_peak )
         {
-            credit_xtra = 1;
+            /* credit_fair is 0 if weight is 0. */
+            if ( sdom->weight != 0 )
+                credit_xtra = 1;
         }
         else
         {
@@ -963,9 +1028,9 @@ csched_acct(void)
         }
 
         /* Compute fair share per VCPU */
+        credit_fair += (sdom->percent * CSCHED_CREDITS_PER_ACCT)/100;
         credit_fair = ( credit_fair + ( sdom->active_vcpu_count - 1 )
                       ) / sdom->active_vcpu_count;
-
 
         list_for_each_safe( iter_vcpu, next_vcpu, &sdom->active_vcpu )
         {
@@ -1029,6 +1094,9 @@ csched_acct(void)
                 }
             }
 
+            /* save credit for adjustment */
+            svc->prev_credit = credit;
+
             CSCHED_VCPU_STAT_SET(svc, credit_last, credit);
             CSCHED_VCPU_STAT_SET(svc, credit_incr, credit_fair);
             credit_balance += credit;
@@ -1282,7 +1350,10 @@ csched_dump_vcpu(struct csched_vcpu *svc
 
     if ( sdom )
     {
-        printk(" credit=%i [w=%u]", atomic_read(&svc->credit), sdom->weight);
+        printk(" credit=%i [w=%u,p=%u]",
+               atomic_read(&svc->credit),
+               sdom->weight,
+               sdom->percent);
 #ifdef CSCHED_STATS
         printk(" (%d+%u) {a/i=%u/%u m=%u+%u}",
                 svc->stats.credit_last,
@@ -1348,6 +1419,8 @@ csched_dump(void)
            "\tcredit balance     = %d\n"
            "\tweight             = %u\n"
            "\trunq_sort          = %u\n"
+           "\tpercent            = %u\n"
+           "\ttotal_percent      = %u\n"
            "\tdefault-weight     = %d\n"
            "\tmsecs per tick     = %dms\n"
            "\tcredits per tick   = %d\n"
@@ -1359,6 +1432,8 @@ csched_dump(void)
            csched_priv.credit_balance,
            csched_priv.weight,
            csched_priv.runq_sort,
+           csched_priv.percent,
+           csched_priv.total_percent,
            CSCHED_DEFAULT_WEIGHT,
            CSCHED_MSECS_PER_TICK,
            CSCHED_CREDITS_PER_TICK,
@@ -1412,6 +1487,8 @@ csched_init(void)
     csched_priv.credit = 0U;
     csched_priv.credit_balance = 0;
     csched_priv.runq_sort = 0U;
+    csched_priv.percent = 0;
+    csched_priv.total_percent = 0;
     CSCHED_STATS_RESET();
 }
 
diff -r 56032cbaf1e8 xen/include/public/domctl.h
--- a/xen/include/public/domctl.h	Thu Jan 22 10:43:50 2009 +0900
+++ b/xen/include/public/domctl.h	Thu Jan 22 13:06:24 2009 +0900
@@ -311,6 +311,7 @@ struct xen_domctl_scheduler_op {
         struct xen_domctl_sched_credit {
             uint16_t weight;
             uint16_t cap;
+            uint16_t percent;
         } credit;
     } u;
 };