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Subject[PATCH v9 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().

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

Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
---
block/blk-core.c | 39 +++++++++++++++++++++++++++++++++++++++
block/elevator.c | 26 ++++++++++++++++++++++++++
2 files changed, 65 insertions(+)

diff --git a/block/blk-core.c b/block/blk-core.c
index ce7d366..81f173e 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -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 */
@@ -2051,6 +2063,28 @@ 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
@@ -2073,6 +2107,11 @@ 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 11683bb..29c5c7e 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -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>

@@ -515,6 +516,27 @@ 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)
{
/*
@@ -529,6 +551,8 @@ 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);
}

@@ -551,6 +575,8 @@ 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) {
--
1.8.1


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