diff options
Diffstat (limited to 'block/blk-core.c')
| -rw-r--r-- | block/blk-core.c | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index c78042975737..3c5f61ceeb67 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -661,7 +661,6 @@ no_merge: * blk_attempt_plug_merge - try to merge with %current's plugged list * @q: request_queue new bio is being queued at * @bio: new bio being queued - * @request_count: out parameter for number of traversed plugged requests * @same_queue_rq: pointer to &struct request that gets filled in when * another request associated with @q is found on the plug list * (optional, may be %NULL) @@ -1683,6 +1682,15 @@ EXPORT_SYMBOL(kblockd_mod_delayed_work_on); * @plug: The &struct blk_plug that needs to be initialized * * Description: + * blk_start_plug() indicates to the block layer an intent by the caller + * to submit multiple I/O requests in a batch. The block layer may use + * this hint to defer submitting I/Os from the caller until blk_finish_plug() + * is called. However, the block layer may choose to submit requests + * before a call to blk_finish_plug() if the number of queued I/Os + * exceeds %BLK_MAX_REQUEST_COUNT, or if the size of the I/O is larger than + * %BLK_PLUG_FLUSH_SIZE. The queued I/Os may also be submitted early if + * the task schedules (see below). + * * Tracking blk_plug inside the task_struct will help with auto-flushing the * pending I/O should the task end up blocking between blk_start_plug() and * blk_finish_plug(). This is important from a performance perspective, but @@ -1765,6 +1773,16 @@ void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule) blk_mq_flush_plug_list(plug, from_schedule); } +/** + * blk_finish_plug - mark the end of a batch of submitted I/O + * @plug: The &struct blk_plug passed to blk_start_plug() + * + * Description: + * Indicate that a batch of I/O submissions is complete. This function + * must be paired with an initial call to blk_start_plug(). The intent + * is to allow the block layer to optimize I/O submission. See the + * documentation for blk_start_plug() for more information. + */ void blk_finish_plug(struct blk_plug *plug) { if (plug != current->plug) |