[Xen-devel] [PATCH v4 25/46] xen/sched: add runstate counters to struct sched_unit

[Juergen Gross <jgross@xxxxxxxx>]

Add counters to struct sched_unit summing up runstates of associated
vcpus. This allows doing quick checks whether a unit has any vcpu
running or whether only a single vcpu of a unit is running.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
RFC V2: add counters for each possible runstate
---
 xen/common/schedule.c   | 5 +++++
 xen/include/xen/sched.h | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/xen/common/schedule.c b/xen/common/schedule.c
index dc68cb912e..772de8de96 100644
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -246,6 +246,7 @@ static inline void vcpu_runstate_change(
     struct vcpu *v, int new_state, s_time_t new_entry_time)
 {
     s_time_t delta;
+    struct sched_unit *unit = v->sched_unit;
 
     ASSERT(v->runstate.state != new_state);
     ASSERT(spin_is_locked(get_sched_res(v->processor)->schedule_lock));
@@ -254,6 +255,9 @@ static inline void vcpu_runstate_change(
 
     trace_runstate_change(v, new_state);
 
+    unit->runstate_cnt[v->runstate.state]--;
+    unit->runstate_cnt[new_state]++;
+
     delta = new_entry_time - v->runstate.state_entry_time;
     if ( delta > 0 )
     {
@@ -378,6 +382,7 @@ static struct sched_unit *sched_alloc_unit(struct vcpu *v)
     unit->vcpu_list = v;
     unit->unit_id = v->vcpu_id;
     unit->domain = d;
+    unit->runstate_cnt[v->runstate.state]++;
 
     for ( prev_unit = &d->sched_unit_list; *prev_unit;
           prev_unit = &(*prev_unit)->next_in_list )
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 6de9ddaaa9..92272256ea 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -277,6 +277,8 @@ struct sched_unit {
 
     /* Last time unit got (de-)scheduled. */
     uint64_t               state_entry_time;
+    /* Vcpu state summary. */
+    unsigned int           runstate_cnt[4];
 
     /* Bitmask of CPUs on which this VCPU may run. */
     cpumask_var_t          cpu_hard_affinity;
-- 
2.16.4


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