File 58b6fd42-credit2-always-mark-a-tickled-pCPU-as-tickled.patch of Package xen.4684

# Commit a76645240bd14e964e85dbc975a8989edea6aa27
# Date 2017-03-01 16:56:34 +0000
# Author Dario Faggioli <dario.faggioli@citrix.com>
# Committer George Dunlap <george.dunlap@citrix.com>
xen: credit2: always mark a tickled pCPU as... tickled!

In fact, whether or not a pCPU has been tickled, and is
therefore about to re-schedule, is something we look at
and base decisions on in various places.

So, let's make sure that we do that basing on accurate
information.

While there, also tweak a little bit smt_idle_mask_clear()
(used for implementing SMT support), so that it only alter
the relevant cpumask when there is the actual need for this.
(This is only for reduced overhead, behavior remains the
same).

Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Reviewed-by: George Dunlap <george.dunlap@eu.citrix.com>

--- a/xen/common/sched_credit2.c
+++ b/xen/common/sched_credit2.c
@@ -559,6 +559,13 @@ __runq_remove(struct csched2_vcpu *svc)
 
 void burn_credits(struct csched2_runqueue_data *rqd, struct csched2_vcpu *, s_time_t);
 
+static inline void
+tickle_cpu(unsigned int cpu, struct csched2_runqueue_data *rqd)
+{
+    cpumask_set_cpu(cpu, &rqd->tickled);
+    cpu_raise_softirq(cpu, SCHEDULE_SOFTIRQ);
+}
+
 /* Check to see if the item on the runqueue is higher priority than what's
  * currently running; if so, wake up the processor */
 static /*inline*/ void
@@ -660,9 +667,8 @@ tickle:
                   sizeof(d),
                   (unsigned char *)&d);
     }
-    cpumask_set_cpu(ipid, &rqd->tickled);
     SCHED_STAT_CRANK(tickle_idlers_some);
-    cpu_raise_softirq(ipid, SCHEDULE_SOFTIRQ);
+    tickle_cpu(ipid, rqd);
 
 no_tickle:
     return;
@@ -1027,7 +1033,7 @@ csched2_vcpu_sleep(const struct schedule
     SCHED_STAT_CRANK(vcpu_sleep);
 
     if ( curr_on_cpu(vc->processor) == vc )
-        cpu_raise_softirq(vc->processor, SCHEDULE_SOFTIRQ);
+        tickle_cpu(vc->processor, svc->rqd);
     else if ( __vcpu_on_runq(svc) )
     {
         BUG_ON(svc->rqd != RQD(ops, vc->processor));
@@ -1308,8 +1314,8 @@ static void migrate(const struct schedul
         svc->migrate_rqd = trqd;
         set_bit(_VPF_migrating, &svc->vcpu->pause_flags);
         set_bit(__CSFLAG_runq_migrate_request, &svc->flags);
-        cpu_raise_softirq(cpu, SCHEDULE_SOFTIRQ);
         SCHED_STAT_CRANK(migrate_requested);
+        tickle_cpu(cpu, svc->rqd);
     }
     else
     {