diff options
| -rw-r--r-- | module/spl/spl-taskq.c | 29 |
1 files changed, 16 insertions, 13 deletions
diff --git a/module/spl/spl-taskq.c b/module/spl/spl-taskq.c index 0b3b3a131..67a834572 100644 --- a/module/spl/spl-taskq.c +++ b/module/spl/spl-taskq.c @@ -156,19 +156,22 @@ task_done(taskq_t *tq, taskq_ent_t *t) * monotonically increasing taskqid and added to the tail of the pending * list. As worker threads become available the tasks are removed from * the head of the pending or priority list, giving preference to the - * priority list. The tasks are then added to the work list, preserving - * the ordering by taskqid. Finally, as tasks complete they are removed - * from the work list. This means that the pending and work lists are - * always kept sorted by taskqid. Thus the lowest outstanding - * incomplete taskqid can be determined simply by checking the min - * taskqid for each head item on the pending, priority, and work list. - * This value is stored in tq->tq_lowest_id and only updated to the new - * lowest id when the previous lowest id completes. All taskqids lower - * than tq->tq_lowest_id must have completed. It is also possible - * larger taskqid's have completed because they may be processed in - * parallel by several worker threads. However, this is not a problem - * because the behavior of taskq_wait_id() is to block until all - * previously submitted taskqid's have completed. + * priority list. The tasks are then removed from their respective + * list, and the taskq_thread servicing the task is added to the active + * list, preserving the order using the serviced task's taskqid. + * Finally, as tasks complete the taskq_thread servicing the task is + * removed from the active list. This means that the pending task and + * active taskq_thread lists are always kept sorted by taskqid. Thus the + * lowest outstanding incomplete taskqid can be determined simply by + * checking the min taskqid for each head item on the pending, priority, + * and active taskq_thread list. This value is stored in + * tq->tq_lowest_id and only updated to the new lowest id when the + * previous lowest id completes. All taskqids lower than + * tq->tq_lowest_id must have completed. It is also possible larger + * taskqid's have completed because they may be processed in parallel by + * several worker threads. However, this is not a problem because the + * behavior of taskq_wait_id() is to block until all previously + * submitted taskqid's have completed. * * XXX: Taskqid_t wrapping is not handled. However, taskqid_t's are * 64-bit values so even if a taskq is processing 2^24 (16,777,216) |