[v2,25/48] xen/sched: add runstate counters to struct sched_unit

Commit Message

Jürgen Groß Aug. 9, 2019, 2:58 p.m. UTC

Add counters to struct sched_unit summing up runstates of associated
vcpus.

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

Comments

Jan Beulich Sept. 9, 2019, 2:30 p.m. UTC | #1

On 09.08.2019 16:58, Juergen Gross wrote:
> Add counters to struct sched_unit summing up runstates of associated
> vcpus.

What use are they (going to be)? Some justification of their
introduction and the associated (however small or large)
overhead of maintaining them would be nice here.

Jan

Patch

diff --git a/xen/common/schedule.c b/xen/common/schedule.c
index 7b0ff8395e..3f8fffc329 100644
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -236,6 +236,7 @@  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));
@@ -244,6 +245,9 @@  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 )
     {
@@ -366,6 +370,7 @@  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 f639b164b5..0cece3b921 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -274,6 +274,8 @@  struct sched_unit {
 
     /* Last time unit got (de-)scheduled. */
     uint64_t               state_entry_time;
+    /* Vcpu state summary. */
+    unsigned int           runstate_cnt[4];
 
     /* Currently running on a CPU? */
     bool                   is_running;