Revert "block: improve queue_should_plug() by looking at IO depths"

This reverts commit fb1e753. "Benjamin S." <[email protected]> reports that the patch in question causes a big drop in sequential throughput for him, dropping from 200MB/sec down to only 70MB/sec. Needs to be investigated more fully, for now lets just revert the offending commit. Conflicts: include/linux/blkdev.h Signed-off-by: Jens Axboe <[email protected]>
torvalds · Feb 23, 2010 · 79da064 · 79da064
1 parent 9f3a628
commit 79da064
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diff --git a/block/blk-core.c b/block/blk-core.c
@@ -1147,7 +1147,7 @@ void init_request_from_bio(struct request *req, struct bio *bio)
  */
 static inline bool queue_should_plug(struct request_queue *q)
 {
- return !(blk_queue_nonrot(q) && blk_queue_queuing(q));
+ return !(blk_queue_nonrot(q) && blk_queue_tagged(q));
 }
 
 static int __make_request(struct request_queue *q, struct bio *bio)
@@ -1859,15 +1859,8 @@ void blk_dequeue_request(struct request *rq)
  * and to it is freed is accounted as io that is in progress at
  * the driver side.
  */
- if (blk_account_rq(rq)) {
+ if (blk_account_rq(rq))
  q->in_flight[rq_is_sync(rq)]++;
- /*
- * Mark this device as supporting hardware queuing, if
- * we have more IOs in flight than 4.
- */
- if (!blk_queue_queuing(q) && queue_in_flight(q) > 4)
- set_bit(QUEUE_FLAG_CQ, &q->queue_flags);
- }
 }
 
 /**

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
@@ -461,8 +461,7 @@ struct request_queue
 #define QUEUE_FLAG_NONROT 14 /* non-rotational device (SSD) */
 #define QUEUE_FLAG_VIRT QUEUE_FLAG_NONROT /* paravirt device */
 #define QUEUE_FLAG_IO_STAT 15 /* do IO stats */
-#define QUEUE_FLAG_CQ 16 /* hardware does queuing */
-#define QUEUE_FLAG_DISCARD 17 /* supports DISCARD */
+#define QUEUE_FLAG_DISCARD 16 /* supports DISCARD */
 
 #define QUEUE_FLAG_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \
  (1 << QUEUE_FLAG_CLUSTER) | \
@@ -586,7 +585,6 @@ enum {
 
 #define blk_queue_plugged(q) test_bit(QUEUE_FLAG_PLUGGED, &(q)->queue_flags)
 #define blk_queue_tagged(q) test_bit(QUEUE_FLAG_QUEUED, &(q)->queue_flags)
-#define blk_queue_queuing(q) test_bit(QUEUE_FLAG_CQ, &(q)->queue_flags)
 #define blk_queue_stopped(q) test_bit(QUEUE_FLAG_STOPPED, &(q)->queue_flags)
 #define blk_queue_nomerges(q) test_bit(QUEUE_FLAG_NOMERGES, &(q)->queue_flags)
 #define blk_queue_nonrot(q) test_bit(QUEUE_FLAG_NONROT, &(q)->queue_flags)