[Xen-devel] [PATCH for 4.7 3/4] xen: credit2: fix 2 (minor) issues in load tracking logic

[Dario Faggioli <dario.faggioli@xxxxxxxxxx>]

All calculations that involve load_last_update uses quantities
shifted by LOADAVG_GRANULARITY_SHIFT, so make sure that this
is true even when the field is assigned a value for the first
time, during vcpu allocation.

Also, during migration, while the loads of both the source and
destination runqueues certainly need changing, the vcpu being
moved does not change its running/non-running status, and its
calculated load should hence not be affected.

Signed-off-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
---
Cc: George Dunlap <george.dunlap@xxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 xen/common/sched_credit2.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/xen/common/sched_credit2.c b/xen/common/sched_credit2.c
index 803cc44..393364a 100644
--- a/xen/common/sched_credit2.c
+++ b/xen/common/sched_credit2.c
@@ -867,7 +867,7 @@ csched2_alloc_vdata(const struct scheduler *ops, struct 
vcpu *vc, void *dd)
         svc->weight = svc->sdom->weight;
         /* Starting load of 50% */
         svc->avgload = 1ULL << (CSCHED2_PRIV(ops)->load_window_shift - 1);
-        svc->load_last_update = NOW();
+        svc->load_last_update = NOW() >> LOADAVG_GRANULARITY_SHIFT;
     }
     else
     {
@@ -1301,7 +1301,7 @@ static void migrate(const struct scheduler *ops,
         if ( __vcpu_on_runq(svc) )
         {
             __runq_remove(svc);
-            update_load(ops, svc->rqd, svc, -1, now);
+            update_load(ops, svc->rqd, NULL, -1, now);
             on_runq=1;
         }
         __runq_deassign(svc);
@@ -1314,7 +1314,7 @@ static void migrate(const struct scheduler *ops,
         __runq_assign(svc, trqd);
         if ( on_runq )
         {
-            update_load(ops, svc->rqd, svc, 1, now);
+            update_load(ops, svc->rqd, NULL, 1, now);
             runq_insert(ops, svc->vcpu->processor, svc);
             runq_tickle(ops, svc->vcpu->processor, svc, now);
             SCHED_STAT_CRANK(migrate_on_runq);


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