diff options
| -rw-r--r-- | sys/kern/sched_4bsd.c | 62 |
1 files changed, 13 insertions, 49 deletions
diff --git a/sys/kern/sched_4bsd.c b/sys/kern/sched_4bsd.c index 28ca5e1..db23e1d 100644 --- a/sys/kern/sched_4bsd.c +++ b/sys/kern/sched_4bsd.c @@ -304,9 +304,8 @@ maybe_resched(struct thread *td) /* * This function is called when a thread is about to be put on run queue * because it has been made runnable or its priority has been adjusted. It - * determines if the new thread should be immediately preempted to. If so, - * it switches to it and eventually returns true. If not, it returns false - * so that the caller may place the thread on an appropriate run queue. + * determines if the new thread should preempt the current thread. If so, + * it sets td_owepreempt to request a preemption. */ int maybe_preempt(struct thread *td) @@ -352,29 +351,8 @@ maybe_preempt(struct thread *td) return (0); #endif - if (ctd->td_critnest > 1) { - CTR1(KTR_PROC, "maybe_preempt: in critical section %d", - ctd->td_critnest); - ctd->td_owepreempt = 1; - return (0); - } - /* - * Thread is runnable but not yet put on system run queue. - */ - MPASS(ctd->td_lock == td->td_lock); - MPASS(TD_ON_RUNQ(td)); - TD_SET_RUNNING(td); - CTR3(KTR_PROC, "preempting to thread %p (pid %d, %s)\n", td, - td->td_proc->p_pid, td->td_name); - mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, td); - /* - * td's lock pointer may have changed. We have to return with it - * locked. - */ - spinlock_enter(); - thread_unlock(ctd); - thread_lock(td); - spinlock_exit(); + CTR0(KTR_PROC, "maybe_preempt: scheduling preemption"); + ctd->td_owepreempt = 1; return (1); #else return (0); @@ -1326,6 +1304,12 @@ sched_add(struct thread *td, int flags) ts->ts_runq = &runq; } + if ((td->td_flags & TDF_NOLOAD) == 0) + sched_load_add(); + runq_add(ts->ts_runq, td, flags); + if (cpu != NOCPU) + runq_length[cpu]++; + cpuid = PCPU_GET(cpuid); if (single_cpu && cpu != cpuid) { kick_other_cpu(td->td_priority, cpu); @@ -1342,18 +1326,10 @@ sched_add(struct thread *td, int flags) } if (!forwarded) { - if ((flags & SRQ_YIELDING) == 0 && maybe_preempt(td)) - return; - else + if (!maybe_preempt(td)) maybe_resched(td); } } - - if ((td->td_flags & TDF_NOLOAD) == 0) - sched_load_add(); - runq_add(ts->ts_runq, td, flags); - if (cpu != NOCPU) - runq_length[cpu]++; } #else /* SMP */ { @@ -1387,23 +1363,11 @@ sched_add(struct thread *td, int flags) CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td); ts->ts_runq = &runq; - /* - * If we are yielding (on the way out anyhow) or the thread - * being saved is US, then don't try be smart about preemption - * or kicking off another CPU as it won't help and may hinder. - * In the YIEDLING case, we are about to run whoever is being - * put in the queue anyhow, and in the OURSELF case, we are - * putting ourself on the run queue which also only happens - * when we are about to yield. - */ - if ((flags & SRQ_YIELDING) == 0) { - if (maybe_preempt(td)) - return; - } if ((td->td_flags & TDF_NOLOAD) == 0) sched_load_add(); runq_add(ts->ts_runq, td, flags); - maybe_resched(td); + if (!maybe_preempt(td)) + maybe_resched(td); } #endif /* SMP */ |
