diff options
Diffstat (limited to 'kern/thread.c')
| -rw-r--r-- | kern/thread.c | 50 |
1 files changed, 27 insertions, 23 deletions
diff --git a/kern/thread.c b/kern/thread.c index b26c3e65..d7f36e6b 100644 --- a/kern/thread.c +++ b/kern/thread.c @@ -897,20 +897,16 @@ thread_sched_ts_start_next_round(struct thread_runq *runq) /* * Check that a remote run queue satisfies the minimum migration requirements. - * - * Note that the highest round can change at any time. */ static int -thread_sched_ts_balance_eligible(struct thread_runq *runq) +thread_sched_ts_balance_eligible(struct thread_runq *runq, + unsigned long highest_round) { - unsigned long highest_round; unsigned int nr_threads; if (runq->ts_weight == 0) return 0; - highest_round = thread_ts_highest_round; - if ((runq->ts_round != highest_round) && (runq->ts_round != (highest_round - 1))) return 0; @@ -930,7 +926,8 @@ thread_sched_ts_balance_eligible(struct thread_runq *runq) * Try to find the most suitable run queue from which to pull threads. */ static struct thread_runq * -thread_sched_ts_balance_scan(struct thread_runq *runq) +thread_sched_ts_balance_scan(struct thread_runq *runq, + unsigned long highest_round) { struct thread_runq *remote_runq, *tmp; unsigned long flags; @@ -950,7 +947,7 @@ thread_sched_ts_balance_scan(struct thread_runq *runq) spinlock_lock(&tmp->lock); - if (!thread_sched_ts_balance_eligible(tmp)) { + if (!thread_sched_ts_balance_eligible(tmp, highest_round)) { spinlock_unlock(&tmp->lock); continue; } @@ -980,12 +977,12 @@ thread_sched_ts_balance_scan(struct thread_runq *runq) static unsigned int thread_sched_ts_balance_migrate(struct thread_runq *runq, - struct thread_runq *remote_runq) + struct thread_runq *remote_runq, + unsigned long highest_round) { struct thread *thread, *tmp; unsigned long flags; unsigned int i, nr_threads; - int pull_from_expired; thread_preempt_disable(); flags = cpu_intr_save(); @@ -993,18 +990,13 @@ thread_sched_ts_balance_migrate(struct thread_runq *runq, i = 0; - if (!thread_sched_ts_balance_eligible(remote_runq)) + if (!thread_sched_ts_balance_eligible(remote_runq, highest_round)) goto out; nr_threads = remote_runq->ts_runq_active->nr_threads; - /* Assume the run queue round is either highest or highest - 1 */ - if (remote_runq->ts_round != (thread_ts_highest_round - 1)) - pull_from_expired = 0; - else { - pull_from_expired = 1; + if (remote_runq->ts_round != highest_round) nr_threads += remote_runq->ts_runq_expired->nr_threads; - } if (nr_threads == 0) goto out; @@ -1030,7 +1022,11 @@ thread_sched_ts_balance_migrate(struct thread_runq *runq, goto out; } - if (pull_from_expired) + /* + * Threads in the expired queue of a processor in round highest are + * actually in round highest + 1. + */ + if (remote_runq->ts_round != highest_round) list_for_each_entry_safe(&remote_runq->ts_runq_expired->threads, thread, tmp, ts_ctx.runq_node) { thread_runq_remove(remote_runq, thread); @@ -1054,15 +1050,21 @@ static void thread_sched_ts_balance(struct thread_runq *runq) { struct thread_runq *remote_runq; - unsigned long flags; + unsigned long flags, highest_round; unsigned int nr_migrations; int i, nr_runqs; /* + * Grab the highest round now and only use the copy so the value is stable + * during the balancing operation. + */ + highest_round = thread_ts_highest_round; + + /* * Don't lock yet as the local run queue round can only be updated * by the balancer thread. */ - if (runq->ts_round != thread_ts_highest_round) { + if (runq->ts_round != highest_round) { spinlock_lock_intr_save(&runq->lock, &flags); if (runq->ts_runq_expired->nr_threads != 0) @@ -1071,10 +1073,11 @@ thread_sched_ts_balance(struct thread_runq *runq) spinlock_unlock_intr_restore(&runq->lock, flags); } - remote_runq = thread_sched_ts_balance_scan(runq); + remote_runq = thread_sched_ts_balance_scan(runq, highest_round); if (remote_runq != NULL) { - nr_migrations = thread_sched_ts_balance_migrate(runq, remote_runq); + nr_migrations = thread_sched_ts_balance_migrate(runq, remote_runq, + highest_round); if (nr_migrations != 0) return; @@ -1092,7 +1095,8 @@ thread_sched_ts_balance(struct thread_runq *runq) if (remote_runq == runq) continue; - nr_migrations = thread_sched_ts_balance_migrate(runq, remote_runq); + nr_migrations = thread_sched_ts_balance_migrate(runq, remote_runq, + highest_round); if (nr_migrations != 0) return; |