diff options
Diffstat (limited to 'kern/thread.c')
| -rw-r--r-- | kern/thread.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/kern/thread.c b/kern/thread.c index 147bd6a1..88537ea5 100644 --- a/kern/thread.c +++ b/kern/thread.c @@ -492,7 +492,9 @@ thread_runq_schedule(struct thread_runq *runq, struct thread *prev) /* * That's where the true context switch occurs. The next thread must - * unlock the run queue and reenable preemption. + * unlock the run queue and reenable preemption. Note that unlocking + * and locking the run queue again is equivalent to a full memory + * barrier. */ tcb_switch(&prev->tcb, &next->tcb); @@ -1096,13 +1098,11 @@ thread_sched_ts_balance_pull(struct thread_runq *runq, * The pinned counter is changed without explicit synchronization. * However, it can only be changed by its owning thread. As threads * currently running aren't considered for migration, the thread had - * to be preempted, and invoke the scheduler, which globally acts - * as a memory barrier. As a result, there is strong ordering between + * to be preempted and invoke the scheduler. Since balancer threads + * acquire the run queue lock, there is strong ordering between * changing the pinned counter and setting the current thread of a - * run queue. Enforce the same ordering on the pulling processor. + * run queue. */ - mb_load(); - if (thread->pinned) continue; |