[PATCH] blk: branch hints

Sprinkle around a few branch hints in the block layer.

Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Jens Axboe <axboe@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/block/ll_rw_blk.c b/drivers/block/ll_rw_blk.c
index 265de85..1e84715 100644 (file)
--- a/drivers/block/ll_rw_blk.c
+++ b/drivers/block/ll_rw_blk.c
@@ -1439,7 +1439,7 @@ EXPORT_SYMBOL(blk_remove_plug);
  */
 void __generic_unplug_device(request_queue_t *q)
 {
-       if (test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags))
+       if (unlikely(test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags)))
                return;
 
        if (!blk_remove_plug(q))
@@ -1763,7 +1763,7 @@ EXPORT_SYMBOL(blk_init_queue_node);
 
 int blk_get_queue(request_queue_t *q)
 {
-       if (!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
+       if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) {
                atomic_inc(&q->refcnt);
                return 0;
        }
@@ -2584,7 +2584,7 @@ static int __make_request(request_queue_t *q, struct bio *bio)
        spin_lock_prefetch(q->queue_lock);
 
        barrier = bio_barrier(bio);
-       if (barrier && (q->ordered == QUEUE_ORDERED_NONE)) {
+       if (unlikely(barrier) && (q->ordered == QUEUE_ORDERED_NONE)) {
                err = -EOPNOTSUPP;
                goto end_io;
        }
@@ -2685,7 +2685,7 @@ get_rq:
        /*
         * REQ_BARRIER implies no merging, but lets make it explicit
         */
-       if (barrier)
+       if (unlikely(barrier))
                req->flags |= (REQ_HARDBARRIER | REQ_NOMERGE);
 
        req->errors = 0;
@@ -2809,7 +2809,7 @@ static inline void block_wait_queue_running(request_queue_t *q)
 {
        DEFINE_WAIT(wait);
 
-       while (test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags)) {
+       while (unlikely(test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags))) {
                struct request_list *rl = &q->rq;
 
                prepare_to_wait_exclusive(&rl->drain, &wait,
@@ -2918,7 +2918,7 @@ end_io:
                        goto end_io;
                }
 
-               if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))
+               if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)))
                        goto end_io;
 
                block_wait_queue_running(q);