[Xen-devel] [PATCH v4 33/46] xen/sched: add a percpu resource index

[Juergen Gross <jgross@xxxxxxxx>]

Add a percpu variable holding the index of the cpu in the current
sched_resource structure. This index is used to get the correct vcpu
of a sched_unit on a specific cpu.

For now this index will be zero for all cpus, but with core scheduling
it will be possible to have higher values, too.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
RFC V2: new patch (carved out from RFC V1 patch 49)
V4:
- make function parameter const (Jan Beulich)
---
 xen/common/schedule.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/xen/common/schedule.c b/xen/common/schedule.c
index b11a1c2538..f79cd2a5a6 100644
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -75,6 +75,7 @@ static void poll_timer_fn(void *data);
 /* This is global for now so that private implementations can reach it */
 DEFINE_PER_CPU(struct scheduler *, scheduler);
 DEFINE_PER_CPU_READ_MOSTLY(struct sched_resource *, sched_res);
+static DEFINE_PER_CPU_READ_MOSTLY(unsigned int, sched_res_idx);
 
 /* Scratch space for cpumasks. */
 DEFINE_PER_CPU(cpumask_t, cpumask_scratch);
@@ -142,6 +143,12 @@ static struct scheduler sched_idle_ops = {
     .switch_sched   = sched_idle_switch_sched,
 };
 
+static inline struct vcpu *sched_unit2vcpu_cpu(const struct sched_unit *unit,
+                                               unsigned int cpu)
+{
+    return unit->domain->vcpu[unit->unit_id + per_cpu(sched_res_idx, cpu)];
+}
+
 static inline struct scheduler *dom_scheduler(const struct domain *d)
 {
     if ( likely(d->cpupool != NULL) )
@@ -2028,7 +2035,7 @@ static void sched_slave(void)
 
     pcpu_schedule_unlock_irq(lock, cpu);
 
-    sched_context_switch(vprev, next->vcpu_list, now);
+    sched_context_switch(vprev, sched_unit2vcpu_cpu(next, cpu), now);
 }
 
 /*
@@ -2089,7 +2096,7 @@ static void schedule(void)
 
     pcpu_schedule_unlock_irq(lock, cpu);
 
-    vnext = next->vcpu_list;
+    vnext = sched_unit2vcpu_cpu(next, cpu);
     sched_context_switch(vprev, vnext, now);
 }
 
-- 
2.16.4


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