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Subject[PATCH v6 3/4] block: implement runtime pm strategy
Date
From: Lin Ming <ming.m.lin@intel.com>

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() and pm_runtime_autosuspend().

When pick a request:
If device is resuming/suspending, then only PM request is allowed to go.
Return NULL for other cases.

[aaron.lu@intel.com: PM request does not involve nr_pending counting]
[aaron.lu@intel.com: No need to check q->dev]
[aaron.lu@intel.com: Autosuspend when the last request finished]
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
---
block/blk-core.c | 7 +++++++
block/elevator.c | 4 ++++
include/linux/blkdev.h | 41 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 52 insertions(+)

diff --git a/block/blk-core.c b/block/blk-core.c
index 6fc24bb..93c1461 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1274,6 +1274,8 @@ 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 */
@@ -2080,6 +2082,11 @@ 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
diff --git a/block/elevator.c b/block/elevator.c
index 9edba1b..61e9b49 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -544,6 +544,8 @@ 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);
}

@@ -566,6 +568,8 @@ 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) {
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index a96e144..884c405 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -974,6 +974,40 @@ extern int blk_pre_runtime_suspend(struct request_queue *q);
extern void blk_post_runtime_suspend(struct request_queue *q, int err);
extern void blk_pre_runtime_resume(struct request_queue *q);
extern void blk_post_runtime_resume(struct request_queue *q, int err);
+
+static inline void blk_pm_put_request(struct request *rq)
+{
+ if (!(rq->cmd_flags & REQ_PM) && !--rq->q->nr_pending) {
+ pm_runtime_mark_last_busy(rq->q->dev);
+ pm_runtime_autosuspend(rq->q->dev);
+ }
+}
+
+static inline struct request *blk_pm_peek_request(
+ struct request_queue *q, struct request *rq)
+{
+ if (q->rpm_status == RPM_SUSPENDED ||
+ (q->rpm_status != RPM_ACTIVE && !(rq->cmd_flags & REQ_PM)))
+ return NULL;
+ else
+ return rq;
+}
+
+static inline void blk_pm_requeue_request(struct request *rq)
+{
+ if (!(rq->cmd_flags & REQ_PM))
+ rq->q->nr_pending--;
+}
+
+static inline void blk_pm_add_request(struct request_queue *q,
+ struct request *rq)
+{
+ if (!(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_runtime_init(struct request_queue *q,
struct device *dev) {}
@@ -984,6 +1018,13 @@ static inline int blk_pre_runtime_suspend(struct request_queue *q)
static inline void blk_post_runtime_suspend(struct request_queue *q, int err) {}
static inline void blk_pre_runtime_resume(struct request_queue *q) {}
static inline void blk_post_runtime_resume(struct request_queue *q, int err) {}
+
+static inline void blk_pm_put_request(struct request *rq) {}
+static inline struct request *blk_pm_peek_request(
+ struct request_queue *q, struct request *rq) { return rq; }
+static inline void blk_pm_requeue_request(struct request *rq) {}
+static inline void blk_pm_add_request(struct request_queue *q,
+ struct request *req) {}
#endif

/*
--
1.7.11.7


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