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SubjectRe: [PATCH v9 3/4] block: implement runtime pm strategy
Hi Alan,

On Tue, Feb 05, 2013 at 04:03:15PM +0800, Aaron Lu wrote:
> 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.

I think I should add the following words in patch 2 & 3's changelog:

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

to reflect your credit if you don't object.

Please let me know what do you think, or if there is a better way to
reflect this, please feel free to let me know.

Thanks,
Aaron

>
> 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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