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Index: sys/kern/sched_4bsd.c
===================================================================
--- sys/kern/sched_4bsd.c
+++ sys/kern/sched_4bsd.c
@@ -816,7 +816,12 @@
static void
sched_priority(struct thread *td, u_char prio)
{
-
+ struct thread *newtd;
+ struct runq *rq;
+ u_char orig_pri;
+#ifdef SMP
+ struct thread *cputd;
+#endif
KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "priority change",
"prio:%d", td->td_priority, "new prio:%d", prio, KTR_ATTR_LINKED,
@@ -832,10 +837,43 @@
THREAD_LOCK_ASSERT(td, MA_OWNED);
if (td->td_priority == prio)
return;
+ orig_pri = td->td_priority;
td->td_priority = prio;
if (TD_ON_RUNQ(td) && td->td_rqindex != (prio / RQ_PPQ)) {
sched_rem(td);
sched_add(td, SRQ_BORING);
+ } else if (orig_pri < prio && TD_IS_RUNNING(td)) {
+ /*
+ * If we have decreased the priority of a running thread, we
+ * have to check if it should be preempted.
+ */
+ rq = &runq;
+ newtd = runq_choose(&runq);
+#ifdef SMP
+ cputd = runq_choose(&runq_pcpu[td->td_oncpu]);
+ if (newtd == NULL ||
+ (cputd != NULL && cputd->td_priority < td->td_priority))
+ newtd = cputd;
+#endif
+
+ if (newtd != NULL && newtd->td_priority < prio
+#ifndef FULL_PREEMPTION
+ && (newtd->td_priority <= PRI_MAX_ITHD ||
+ prio >= PRI_MIN_IDLE))
+#endif
+ ) {
+ if (td == curthread)
+ /*
+ * Don't reschedule the thread here as it may
+ * be losing priority because it has released a
+ * mutex, and in that case we need it to finish
+ * releasing the lock before it gets preempted.
+ */
+ td->td_owepreempt = 1;
+ else
+ kick_other_cpu(newtd->td_priority,
+ td->td_oncpu);
+ }
}
}
Index: sys/kern/sched_ule.c
===================================================================
--- sys/kern/sched_ule.c
+++ sys/kern/sched_ule.c
@@ -319,7 +319,7 @@
#ifdef SMP
static int tdq_move(struct tdq *, struct tdq *);
static int tdq_idled(struct tdq *);
-static void tdq_notify(struct tdq *, struct thread *);
+static void tdq_notify(struct tdq *, int);
static struct thread *tdq_steal(struct tdq *, int);
static struct thread *runq_steal(struct runq *, int);
static int sched_pickcpu(struct thread *, int);
@@ -1040,16 +1040,14 @@
* Notify a remote cpu of new work. Sends an IPI if criteria are met.
*/
static void
-tdq_notify(struct tdq *tdq, struct thread *td)
+tdq_notify(struct tdq *tdq, int pri)
{
struct thread *ctd;
- int pri;
int cpu;
if (tdq->tdq_ipipending)
return;
- cpu = td_get_sched(td)->ts_cpu;
- pri = td->td_priority;
+ cpu = TD_ID(tdq);
ctd = pcpu_find(cpu)->pc_curthread;
if (!sched_shouldpreempt(pri, ctd->td_priority, 1))
return;
@@ -1675,6 +1673,22 @@
ts->ts_ltick = t;
}
+static void
+sched_check_preempt(struct tdq *tdq, struct thread *td)
+{
+
+ KASSERT(TD_IS_RUNNING(td), ("thread is not running"));
+ TDQ_LOCK_ASSERT(tdq, MA_OWNED);
+ KASSERT(tdq == TDQ_CPU(td->td_sched->ts_cpu),
+ ("tdq does not contain td"));
+
+ if (tdq == TDQ_SELF()) {
+ if (sched_shouldpreempt(tdq->tdq_lowpri, td->td_priority, 0))
+ td->td_owepreempt = 1;
+ } else
+ tdq_notify(tdq, tdq->tdq_lowpri);
+}
+
/*
* Adjust the priority of a thread. Move it to the appropriate run-queue
* if necessary. This is the back-end for several priority related
@@ -1726,6 +1740,9 @@
tdq->tdq_lowpri = prio;
else if (tdq->tdq_lowpri == oldpri)
tdq_setlowpri(tdq, td);
+
+ if (oldpri < prio)
+ sched_check_preempt(tdq, td);
return;
}
td->td_priority = prio;
@@ -1854,7 +1871,7 @@
*/
tdq_lock_pair(tdn, tdq);
tdq_add(tdn, td, flags);
- tdq_notify(tdn, td);
+ tdq_notify(tdn, td->td_priority);
TDQ_UNLOCK(tdn);
spinlock_exit();
#endif
@@ -2429,7 +2446,7 @@
tdq = sched_setcpu(td, cpu, flags);
tdq_add(tdq, td, flags);
if (cpu != PCPU_GET(cpuid)) {
- tdq_notify(tdq, td);
+ tdq_notify(tdq, td->td_priority);
return;
}
#else

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