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Commit a68bbddb authored by Jens Axboe's avatar Jens Axboe
Browse files

block: add queue flag for SSD/non-rotational devices 



We don't want to idle in AS/CFQ if the device doesn't have a seek
penalty. So add a QUEUE_FLAG_NONROT to indicate a non-rotational
device, low level drivers should set this flag upon discovery of
an SSD or similar device type.

Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 9e49184c

block/as-iosched.c

+6 −0
Original line number Diff line number Diff line
@@ -745,6 +745,12 @@ static int as_can_break_anticipation(struct as_data *ad, struct request *rq) 
 */

static int as_can_anticipate(struct as_data *ad, struct request *rq)

{

	/*

	 * SSD device without seek penalty, disable idling

	 */

	if (blk_queue_nonrot(ad->q))

		return 0;



	if (!ad->io_context)

		/*

		 * Last request submitted was a write

block/cfq-iosched.c

+6 −0
Original line number Diff line number Diff line
@@ -878,6 +878,12 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd) 
	struct cfq_io_context *cic;

	unsigned long sl;



	/*

	 * SSD device without seek penalty, disable idling

	 */

	if (blk_queue_nonrot(cfqd->queue))

		return;



	WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));

	WARN_ON(cfq_cfqq_slice_new(cfqq));

include/linux/blkdev.h

+2 −0
Original line number Diff line number Diff line
@@ -442,6 +442,7 @@ struct request_queue 
#define QUEUE_FLAG_SAME_COMP   11	/* force complete on same CPU */

#define QUEUE_FLAG_FAIL_IO     12	/* fake timeout */

#define QUEUE_FLAG_STACKABLE   13	/* supports request stacking */

#define QUEUE_FLAG_NONROT      14	/* non-rotational device (SSD) */



static inline int queue_is_locked(struct request_queue *q)

{
@@ -547,6 +548,7 @@ enum { 
#define blk_queue_tagged(q)	test_bit(QUEUE_FLAG_QUEUED, &(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)

#define blk_queue_flushing(q)	((q)->ordseq)

#define blk_queue_stackable(q)	\

	test_bit(QUEUE_FLAG_STACKABLE, &(q)->queue_flags)