diff -r 76e1f7018b01 xen/common/sched_credit.c
--- a/xen/common/sched_credit.c Mon Jan 31 08:10:00 2011 +0100
+++ b/xen/common/sched_credit.c Wed Feb 02 10:59:44 2011 +0100
@@ -50,6 +50,8 @@
     (CSCHED_CREDITS_PER_MSEC * CSCHED_MSECS_PER_TSLICE)
 #define CSCHED_CREDITS_PER_ACCT     \
     (CSCHED_CREDITS_PER_MSEC * CSCHED_MSECS_PER_TICK * CSCHED_TICKS_PER_ACCT)
+#define CSCHED_ACCT_TSLICE          \
+    (MILLISECS(CSCHED_MSECS_PER_TICK) * CSCHED_TICKS_PER_ACCT)
 
 
 /*
@@ -320,6 +322,7 @@ csched_free_pdata(const struct scheduler
     struct csched_private *prv = CSCHED_PRIV(ops);
     struct csched_pcpu *spc = pcpu;
     unsigned long flags;
+    uint64_t now = NOW();
 
     if ( spc == NULL )
         return;
@@ -334,6 +337,8 @@ csched_free_pdata(const struct scheduler
     {
         prv->master = first_cpu(prv->cpus);
         migrate_timer(&prv->master_ticker, prv->master);
+        set_timer(&prv->master_ticker, now + CSCHED_ACCT_TSLICE
+            - now % CSCHED_ACCT_TSLICE);
     }
     kill_timer(&spc->ticker);
     if ( prv->ncpus == 0 )
@@ -367,8 +372,7 @@ csched_alloc_pdata(const struct schedule
     {
         prv->master = cpu;
         init_timer(&prv->master_ticker, csched_acct, prv, cpu);
-        set_timer(&prv->master_ticker, NOW() +
-                  MILLISECS(CSCHED_MSECS_PER_TICK) * CSCHED_TICKS_PER_ACCT);
+        set_timer(&prv->master_ticker, NOW() + CSCHED_ACCT_TSLICE);
     }
 
     init_timer(&spc->ticker, csched_tick, (void *)(unsigned long)cpu, cpu);
@@ -1138,8 +1142,7 @@ csched_acct(void* dummy)
     prv->runq_sort++;
 
 out:
-    set_timer( &prv->master_ticker, NOW() +
-            MILLISECS(CSCHED_MSECS_PER_TICK) * CSCHED_TICKS_PER_ACCT );
+    set_timer( &prv->master_ticker, NOW() + CSCHED_ACCT_TSLICE );
 }
 
 static void
@@ -1531,22 +1534,31 @@ csched_deinit(const struct scheduler *op
 
 static void csched_tick_suspend(const struct scheduler *ops, unsigned int cpu)
 {
+    struct csched_private *prv;
     struct csched_pcpu *spc;
 
+    prv = CSCHED_PRIV(ops);
     spc = CSCHED_PCPU(cpu);
 
     stop_timer(&spc->ticker);
+    if ( prv->master == cpu )
+        stop_timer(&prv->master_ticker);
 }
 
 static void csched_tick_resume(const struct scheduler *ops, unsigned int cpu)
 {
+    struct csched_private *prv;
     struct csched_pcpu *spc;
     uint64_t now = NOW();
 
+    prv = CSCHED_PRIV(ops);
     spc = CSCHED_PCPU(cpu);
 
     set_timer(&spc->ticker, now + MILLISECS(CSCHED_MSECS_PER_TICK)
             - now % MILLISECS(CSCHED_MSECS_PER_TICK) );
+    if ( prv->master == cpu )
+        set_timer(&prv->master_ticker, now + CSCHED_ACCT_TSLICE
+            - now % CSCHED_ACCT_TSLICE);
 }
 
 static struct csched_private _csched_priv;