# HG changeset patch
# User George Dunlap <george.dunlap@xxxxxxxxxxxxx>
# Date 1322758205 0
# Node ID e122485df37b57f58dbf13ec81a18169c0a7e90f
# Parent  96bbdc894224821fbc14a33e93b55688920c7fd2
imported patch credit_2.patch

diff -r c613d436ca09 xen/common/sched_credit.c
--- a/xen/common/sched_credit.c	Tue Nov 22 19:03:04 2011 +0000
+++ b/xen/common/sched_credit.c	Thu Dec 01 17:15:12 2011 +0000
@@ -115,6 +115,10 @@ static bool_t __read_mostly sched_credit
 boolean_param("sched_credit_default_yield", sched_credit_default_yield);
 
 /*
+ * Scheduler generic parameters
+ */
+extern int sched_ratelimit_us;
+/*
  * Physical CPU
  */
 struct csched_pcpu {
@@ -1299,10 +1303,15 @@ csched_schedule(
     struct csched_private *prv = CSCHED_PRIV(ops);
     struct csched_vcpu *snext;
     struct task_slice ret;
+    s_time_t runtime, tslice;
+    struct schedule_data *sd;
 
     CSCHED_STAT_CRANK(schedule);
     CSCHED_VCPU_CHECK(current);
 
+    runtime = now - current->runstate.state_entry_time;
+    if ( runtime < 0 ) /* Does this ever happen? */
+        runtime = 0;
     if ( !is_idle_vcpu(scurr->vcpu) )
     {
         /* Update credits of a non-idle VCPU. */
@@ -1314,7 +1323,33 @@ csched_schedule(
         /* Re-instate a boosted idle VCPU as normal-idle. */
         scurr->pri = CSCHED_PRI_IDLE;
     }
-
+    /* If we have schedule rate limiting enabled, check to see
+     * how long we've run for. */
+  
+    if ( sched_ratelimit_us
+         && vcpu_runnable(current)
+         && !is_idle_vcpu(current)
+         && runtime < MICROSECS(sched_ratelimit_us) )
+    {
+        snext = scurr;
+        perfc_incr(delay_ms);
+        /* FIXME: Use prv->tslice_ms if we're also the head of hte queue */
+        //tslice = MICROSECS(sched_ratelimit_us);
+        tslice = MILLISECS(sched_ratelimit_us);
+	ret.time = tslice;
+	ret.task = snext->vcpu;
+	ret.migrated = 0;
+	CSCHED_VCPU_CHECK(ret.task);
+    	return ret;
+    }
+    else
+    {
+        /*
+         * Select next runnable local VCPU (ie top of local runq)
+         */
+        tslice = MILLISECS(CSCHED_MSECS_PER_TSLICE);
+    }
+    
     /*
      * Select next runnable local VCPU (ie top of local runq)
      */
@@ -1373,7 +1408,7 @@ csched_schedule(
      * Return task to run next...
      */
     ret.time = (is_idle_vcpu(snext->vcpu) ?
-                -1 : MILLISECS(CSCHED_MSECS_PER_TSLICE));
+                -1 : tslice);
     ret.task = snext->vcpu;
 
     CSCHED_VCPU_CHECK(ret.task);
diff -r c613d436ca09 xen/common/schedule.c
--- a/xen/common/schedule.c	Tue Nov 22 19:03:04 2011 +0000
+++ b/xen/common/schedule.c	Thu Dec 01 17:15:12 2011 +0000
@@ -47,6 +47,10 @@ string_param("sched", opt_sched);
 bool_t sched_smt_power_savings = 0;
 boolean_param("sched_smt_power_savings", sched_smt_power_savings);
 
+/* Default scheduling rate limit: 1ms */
+int sched_ratelimit_us = 1000;
+integer_param("sched_ratelimit_us", sched_ratelimit_us);
+
 /* Various timer handlers. */
 static void s_timer_fn(void *unused);
 static void vcpu_periodic_timer_fn(void *data);
diff -r c613d436ca09 xen/include/xen/perfc_defn.h
--- a/xen/include/xen/perfc_defn.h	Tue Nov 22 19:03:04 2011 +0000
+++ b/xen/include/xen/perfc_defn.h	Thu Dec 01 17:15:12 2011 +0000
@@ -20,6 +20,7 @@ PERFCOUNTER(vcpu_check,             "csc
 PERFCOUNTER(schedule,               "csched: schedule")
 PERFCOUNTER(acct_run,               "csched: acct_run")
 PERFCOUNTER(acct_no_work,           "csched: acct_no_work")
+PERFCOUNTER(delay_ms,		    "csched: 1ms delay")
 PERFCOUNTER(acct_balance,           "csched: acct_balance")
 PERFCOUNTER(acct_reorder,           "csched: acct_reorder")
 PERFCOUNTER(acct_min_credit,        "csched: acct_min_credit")