Commit c8158819 authored by Lin Ming's avatar Lin Ming Committed by Jens Axboe
Browse files

block: implement runtime pm strategy 

When a request is added:
    If device is suspended or is suspending and the request is not a
    PM request, resume the device.

When the last request finishes:
    Call pm_runtime_mark_last_busy().

When pick a request:
    If device is resuming/suspending, then only PM request is allowed
    to go.

The idea and API is designed by Alan Stern and described here:
http://marc.info/?l=linux-scsi&m=133727953625963&w=2



Signed-off-by: default avatarLin Ming <ming.m.lin@intel.com>
Signed-off-by: default avatarAaron Lu <aaron.lu@intel.com>
Acked-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 6c954667

block/blk-core.c

+39 −0
Original line number Diff line number Diff line
@@ -1264,6 +1264,16 @@ void part_round_stats(int cpu, struct hd_struct *part) 
}

EXPORT_SYMBOL_GPL(part_round_stats);



#ifdef CONFIG_PM_RUNTIME

static void blk_pm_put_request(struct request *rq)

{

	if (rq->q->dev && !(rq->cmd_flags & REQ_PM) && !--rq->q->nr_pending)

		pm_runtime_mark_last_busy(rq->q->dev);

}

#else

static inline void blk_pm_put_request(struct request *rq) {}

#endif



/*

 * queue lock must be held

 */
@@ -1274,6 +1284,8 @@ void __blk_put_request(struct request_queue *q, struct request *req) 
	if (unlikely(--req->ref_count))

		return;



	blk_pm_put_request(req);



	elv_completed_request(q, req);



	/* this is a bio leak */
@@ -2053,6 +2065,28 @@ static void blk_account_io_done(struct request *req) 
	}

}



#ifdef CONFIG_PM_RUNTIME

/*

 * Don't process normal requests when queue is suspended

 * or in the process of suspending/resuming

 */

static struct request *blk_pm_peek_request(struct request_queue *q,

					   struct request *rq)

{

	if (q->dev && (q->rpm_status == RPM_SUSPENDED ||

	    (q->rpm_status != RPM_ACTIVE && !(rq->cmd_flags & REQ_PM))))

		return NULL;

	else

		return rq;

}

#else

static inline struct request *blk_pm_peek_request(struct request_queue *q,

						  struct request *rq)

{

	return rq;

}

#endif



/**

 * blk_peek_request - peek at the top of a request queue

 * @q: request queue to peek at
@@ -2075,6 +2109,11 @@ struct request *blk_peek_request(struct request_queue *q) 
	int ret;



	while ((rq = __elv_next_request(q)) != NULL) {



		rq = blk_pm_peek_request(q, rq);

		if (!rq)

			break;



		if (!(rq->cmd_flags & REQ_STARTED)) {

			/*

			 * This is the first time the device driver

block/elevator.c

+26 −0
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ 
#include <linux/blktrace_api.h>

#include <linux/hash.h>

#include <linux/uaccess.h>

#include <linux/pm_runtime.h>



#include <trace/events/block.h>
@@ -536,6 +537,27 @@ void elv_bio_merged(struct request_queue *q, struct request *rq, 
		e->type->ops.elevator_bio_merged_fn(q, rq, bio);

}



#ifdef CONFIG_PM_RUNTIME

static void blk_pm_requeue_request(struct request *rq)

{

	if (rq->q->dev && !(rq->cmd_flags & REQ_PM))

		rq->q->nr_pending--;

}



static void blk_pm_add_request(struct request_queue *q, struct request *rq)

{

	if (q->dev && !(rq->cmd_flags & REQ_PM) && q->nr_pending++ == 0 &&

	    (q->rpm_status == RPM_SUSPENDED || q->rpm_status == RPM_SUSPENDING))

		pm_request_resume(q->dev);

}

#else

static inline void blk_pm_requeue_request(struct request *rq) {}

static inline void blk_pm_add_request(struct request_queue *q,

				      struct request *rq)

{

}

#endif



void elv_requeue_request(struct request_queue *q, struct request *rq)

{

	/*
@@ -550,6 +572,8 @@ void elv_requeue_request(struct request_queue *q, struct request *rq) 


	rq->cmd_flags &= ~REQ_STARTED;



	blk_pm_requeue_request(rq);



	__elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE);

}
@@ -572,6 +596,8 @@ void __elv_add_request(struct request_queue *q, struct request *rq, int where) 
{

	trace_block_rq_insert(q, rq);



	blk_pm_add_request(q, rq);



	rq->q = q;



	if (rq->cmd_flags & REQ_SOFTBARRIER) {

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