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Message-ID: <20120324163542.GA23888@envy17>
Date: Sat, 24 Mar 2012 09:35:42 -0700
From: mark gross <markgross@...gnar.org>
To: MyungJoo Ham <myungjoo.ham@...sung.com>
Cc: "Rafael J. Wysocki" <rjw@...k.pl>, linux-pm@...r.kernel.org,
Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
Kevin Hilman <khilman@...com>, Jean Pihet <j-pihet@...com>,
markgross <markgross@...gnar.org>, kyungmin.park@...sung.com,
myungjoo.ham@...il.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] PM / QoS: add pm_qos_update_request_timeout API
I apologize for the lat replay and admit that I was probably wrong to
oppose the idea of time out pm_qos requests. (last week we bumped into
a need for them and now I get it.)
On Wed, Mar 07, 2012 at 02:06:18PM +0900, MyungJoo Ham wrote:
> The new API, pm_qos_update_request_timeout() is to provide a timeout
> with pm_qos_update_request.
>
> For example, pm_qos_update_request_timeout(req, 100, 1000), means that
> QoS request on req with value 100 will be active for 1000 jiffies.
> After 1000 jiffies, the QoS request thru req is rolled back to the
> request status when pm_qos_update_request_timeout() was called. If there
> were another pm_qos_update_request(req, x) during the 1000 jiffies, this
> new request with value x will override as this is another request on the
> same req handle. A new request on the same req handle will always
> override the previous request whether it is the conventional request or
> it is the new timeout request.
>
> Signed-off-by: MyungJoo Ham <myungjoo.ham@...sung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>
> ---
> Changes from v2
> - Rebased to avoid merge conflict
> Chages from v1(RFC)
> - The semmantics of timeout changed. A timeout now means that the
> corresponding qos-req object is being cancelled, not rolling back to
> the qos request state at the time of API call. With this changes,
> combined with the conventional update_request API, there exists up to
> only one qos request per qos-req object.
> - The timeout values is expressed in ms (1/1000 sec), not jiffies.
> - Style changes, removing unnecessary changes.
> - Bugfixes regarding pending timeout work.
>
> ---
> include/linux/pm_qos.h | 4 +++
> kernel/power/qos.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 54 insertions(+), 0 deletions(-)
>
> diff --git a/include/linux/pm_qos.h b/include/linux/pm_qos.h
> index 0ee7caa..6f347fe 100644
> --- a/include/linux/pm_qos.h
> +++ b/include/linux/pm_qos.h
> @@ -8,6 +8,7 @@
> #include <linux/notifier.h>
> #include <linux/miscdevice.h>
> #include <linux/device.h>
> +#include <linux/workqueue.h>
>
> enum {
> PM_QOS_RESERVED = 0,
> @@ -33,6 +34,7 @@ enum {
> struct pm_qos_request {
> struct plist_node node;
> int pm_qos_class;
> + struct delayed_work work; /* for pm_qos_update_request_timeout */
> };
>
> struct dev_pm_qos_request {
> @@ -77,6 +79,8 @@ void pm_qos_add_request(struct pm_qos_request *req, int pm_qos_class,
> s32 value);
> void pm_qos_update_request(struct pm_qos_request *req,
> s32 new_value);
> +void pm_qos_update_request_timeout(struct pm_qos_request *req,
> + s32 new_value, unsigned long timeout_ms);
is ms the right units? could we ever need us?
> void pm_qos_remove_request(struct pm_qos_request *req);
>
> int pm_qos_request(int pm_qos_class);
> diff --git a/kernel/power/qos.c b/kernel/power/qos.c
> index 3e122db..8ac8eca 100644
> --- a/kernel/power/qos.c
> +++ b/kernel/power/qos.c
> @@ -259,6 +259,21 @@ int pm_qos_request_active(struct pm_qos_request *req)
> EXPORT_SYMBOL_GPL(pm_qos_request_active);
>
> /**
> + * pm_qos_work_fn - the timeout handler of pm_qos_update_request_timeout
> + * @work: work struct for the delayed work (timeout)
> + *
> + * This cancels the timeout request by falling back to the default at timeout.
> + */
> +static void pm_qos_work_fn(struct work_struct *work)
> +{
> + struct pm_qos_request *req = container_of(to_delayed_work(work),
> + struct pm_qos_request,
> + work);
> +
> + pm_qos_update_request(req, PM_QOS_DEFAULT_VALUE);
> +}
> +
> +/**
> * pm_qos_add_request - inserts new qos request into the list
> * @req: pointer to a preallocated handle
> * @pm_qos_class: identifies which list of qos request to use
> @@ -282,6 +297,7 @@ void pm_qos_add_request(struct pm_qos_request *req,
> return;
> }
> req->pm_qos_class = pm_qos_class;
> + INIT_DELAYED_WORK(&req->work, pm_qos_work_fn);
> pm_qos_update_target(pm_qos_array[pm_qos_class]->constraints,
> &req->node, PM_QOS_ADD_REQ, value);
> }
> @@ -308,6 +324,9 @@ void pm_qos_update_request(struct pm_qos_request *req,
> return;
> }
>
> + if (delayed_work_pending(&req->work))
> + cancel_delayed_work_sync(&req->work);
> +
> if (new_value != req->node.prio)
> pm_qos_update_target(
> pm_qos_array[req->pm_qos_class]->constraints,
> @@ -316,6 +335,34 @@ void pm_qos_update_request(struct pm_qos_request *req,
> EXPORT_SYMBOL_GPL(pm_qos_update_request);
>
> /**
> + * pm_qos_update_request_timeout - modifies an existing qos request temporarily.
> + * @req : handle to list element holding a pm_qos request to use
> + * @new_value: defines the temporal qos request
> + * @timeout_ms: the effective duration of this qos request in msecs.
> + *
> + * After timeout_ms, this qos request is cancelled automatically.
> + */
> +void pm_qos_update_request_timeout(struct pm_qos_request *req, s32 new_value,
> + unsigned long timeout_ms)
> +{
> + if (!req)
> + return;
> + if (WARN(!pm_qos_request_active(req),
> + "%s called for unknown object.", __func__))
> + return;
> +
> + if (delayed_work_pending(&req->work))
> + cancel_delayed_work_sync(&req->work);
> +
> + if (new_value != req->node.prio)
> + pm_qos_update_target(
> + pm_qos_array[req->pm_qos_class]->constraints,
> + &req->node, PM_QOS_UPDATE_REQ, new_value);
> +
> + schedule_delayed_work(&req->work, msecs_to_jiffies(timeout_ms));
> +}
> +
> +/**
> * pm_qos_remove_request - modifies an existing qos request
> * @req: handle to request list element
> *
> @@ -334,6 +381,9 @@ void pm_qos_remove_request(struct pm_qos_request *req)
> return;
> }
>
> + if (delayed_work_pending(&req->work))
> + cancel_delayed_work_sync(&req->work);
> +
> pm_qos_update_target(pm_qos_array[req->pm_qos_class]->constraints,
> &req->node, PM_QOS_REMOVE_REQ,
> PM_QOS_DEFAULT_VALUE);
> --
> 1.7.4.1
>
Acked-by: Mark Gross <markgross@...gnar.org>
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