[Xen-devel] [PATCH v2 2/2] xen: sched: rtds: use non-atomic bit-ops

[Tianyang Chen <tiche@xxxxxxxxxxxxx>]

Vcpu flags are checked and cleared atomically. Performance can be
improved with corresponding non-atomic versions since schedule.c
already has spin_locks in place.

Signed-off-by: Tianyang Chen <tiche@xxxxxxxxxxxxx>
---
Changes since v1:
    -none
---
 xen/common/sched_rt.c |   16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/xen/common/sched_rt.c b/xen/common/sched_rt.c
index 255d1f6..8ecc908 100644
--- a/xen/common/sched_rt.c
+++ b/xen/common/sched_rt.c
@@ -936,7 +936,7 @@ burn_budget(const struct scheduler *ops, struct rt_vcpu 
*svc, s_time_t now)
     if ( svc->cur_budget <= 0 )
     {
         svc->cur_budget = 0;
-        set_bit(__RTDS_depleted, &svc->flags);
+        __set_bit(__RTDS_depleted, &svc->flags);
     }
 
     /* TRACE */
@@ -1050,7 +1050,7 @@ rt_schedule(const struct scheduler *ops, s_time_t now, 
bool_t tasklet_work_sched
     if ( snext != scurr &&
          !is_idle_vcpu(current) &&
          vcpu_runnable(current) )
-        set_bit(__RTDS_delayed_runq_add, &scurr->flags);
+        __set_bit(__RTDS_delayed_runq_add, &scurr->flags);
 
     snext->last_start = now;
     ret.time =  -1; /* if an idle vcpu is picked */
@@ -1059,7 +1059,7 @@ rt_schedule(const struct scheduler *ops, s_time_t now, 
bool_t tasklet_work_sched
         if ( snext != scurr )
         {
             q_remove(snext);
-            set_bit(__RTDS_scheduled, &snext->flags);
+            __set_bit(__RTDS_scheduled, &snext->flags);
         }
         if ( snext->vcpu->processor != cpu )
         {
@@ -1093,7 +1093,7 @@ rt_vcpu_sleep(const struct scheduler *ops, struct vcpu 
*vc)
         replq_remove(ops, svc);
     }
     else if ( svc->flags & RTDS_delayed_runq_add )
-        clear_bit(__RTDS_delayed_runq_add, &svc->flags);
+        __clear_bit(__RTDS_delayed_runq_add, &svc->flags);
 }
 
 /*
@@ -1235,7 +1235,7 @@ rt_vcpu_wake(const struct scheduler *ops, struct vcpu *vc)
      */
     if ( unlikely(svc->flags & RTDS_scheduled) )
     {
-        set_bit(__RTDS_delayed_runq_add, &svc->flags);
+        __set_bit(__RTDS_delayed_runq_add, &svc->flags);
         /*
          * The vcpu is waking up already, and we didn't even had the time to
          * remove its next replenishment event from the replenishment queue
@@ -1266,12 +1266,12 @@ rt_context_saved(const struct scheduler *ops, struct 
vcpu *vc)
     struct rt_vcpu *svc = rt_vcpu(vc);
     spinlock_t *lock = vcpu_schedule_lock_irq(vc);
 
-    clear_bit(__RTDS_scheduled, &svc->flags);
+    __clear_bit(__RTDS_scheduled, &svc->flags);
     /* not insert idle vcpu to runq */
     if ( is_idle_vcpu(vc) )
         goto out;
 
-    if ( test_and_clear_bit(__RTDS_delayed_runq_add, &svc->flags) &&
+    if ( __test_and_clear_bit(__RTDS_delayed_runq_add, &svc->flags) &&
          likely(vcpu_runnable(vc)) )
     {
         runq_insert(ops, svc);
@@ -1447,7 +1447,7 @@ static void repl_timer_handler(void *data){
                 runq_tickle(ops, next_on_runq);
         }
         else if ( vcpu_on_q(svc) &&
-                  test_and_clear_bit(__RTDS_depleted, &svc->flags) )
+                  __test_and_clear_bit(__RTDS_depleted, &svc->flags) )
             runq_tickle(ops, svc);
 
         list_del(&svc->replq_elem);
-- 
1.7.9.5


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