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Date: Mon, 17 Feb 2014 18:23:51 +0100
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Chuansheng Liu <chuansheng.liu@...el.com>
Cc: gregkh@...uxfoundation.org, len.brown@...el.com, pavel@....cz,
linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
zhuangzhi.li@...el.com
Subject: Re: [PATCH v3 2/5] PM / sleep: Asynchronous threads for resume_noirq
On Monday, February 17, 2014 02:19:11 PM Chuansheng Liu wrote:
> In analogy with commits 5af84b82701a and 97df8c12995, using
> asynchronous threads can improve the overall resume_noirq time
> significantly.
>
> One typical case is:
> In resume_noirq phase and for the PCI devices, the function
> pci_pm_resume_noirq() will be called, and there is one d3_delay
> (10ms) at least.
>
> With the way of asynchronous threads, we just need wait d3_delay
> time once in parallel for each calling, which saves much time to
> resume quickly.
>
> Signed-off-by: Chuansheng Liu <chuansheng.liu@...el.com>
> ---
> drivers/base/power/main.c | 66 +++++++++++++++++++++++++++++++++++------------
> 1 file changed, 50 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
> index 00c53eb..89172aa 100644
> --- a/drivers/base/power/main.c
> +++ b/drivers/base/power/main.c
> @@ -469,7 +469,7 @@ static void dpm_watchdog_clear(struct dpm_watchdog *wd)
> * The driver of @dev will not receive interrupts while this function is being
> * executed.
> */
> -static int device_resume_noirq(struct device *dev, pm_message_t state)
> +static int device_resume_noirq(struct device *dev, pm_message_t state, bool async)
> {
> pm_callback_t callback = NULL;
> char *info = NULL;
> @@ -481,6 +481,8 @@ static int device_resume_noirq(struct device *dev, pm_message_t state)
> if (dev->power.syscore)
> goto Out;
>
> + dpm_wait(dev->parent, async);
> +
That is too early to wait. Please move it under the next check.
> if (!dev->power.is_noirq_suspended)
> goto Out;
>
> @@ -507,10 +509,29 @@ static int device_resume_noirq(struct device *dev, pm_message_t state)
> dev->power.is_noirq_suspended = false;
>
> Out:
> + complete_all(&dev->power.completion);
> TRACE_RESUME(error);
> return error;
> }
>
> +static bool is_async(struct device *dev)
> +{
> + return dev->power.async_suspend && pm_async_enabled
> + && !pm_trace_is_enabled();
> +}
> +
> +static void async_resume_noirq(void *data, async_cookie_t cookie)
> +{
> + struct device *dev = (struct device *)data;
> + int error;
> +
> + error = device_resume_noirq(dev, pm_transition, true);
> + if (error)
> + pm_dev_err(dev, pm_transition, " async", error);
> +
> + put_device(dev);
> +}
> +
> /**
> * dpm_resume_noirq - Execute "noirq resume" callbacks for all devices.
> * @state: PM transition of the system being carried out.
> @@ -520,29 +541,48 @@ static int device_resume_noirq(struct device *dev, pm_message_t state)
> */
> static void dpm_resume_noirq(pm_message_t state)
> {
> + struct device *dev;
> ktime_t starttime = ktime_get();
>
> mutex_lock(&dpm_list_mtx);
> - while (!list_empty(&dpm_noirq_list)) {
> - struct device *dev = to_device(dpm_noirq_list.next);
> - int error;
> + pm_transition = state;
> +
> + /*
> + * Advanced the async threads upfront,
> + * in case the starting of async threads is
> + * delayed by non-async resuming devices.
> + */
> + list_for_each_entry(dev, &dpm_noirq_list, power.entry) {
> + reinit_completion(&dev->power.completion);
> + if (is_async(dev)) {
> + get_device(dev);
> + async_schedule(async_resume_noirq, dev);
> + }
> + }
>
> + while (!list_empty(&dpm_noirq_list)) {
> + dev = to_device(dpm_noirq_list.next);
> get_device(dev);
> list_move_tail(&dev->power.entry, &dpm_late_early_list);
> mutex_unlock(&dpm_list_mtx);
>
> - error = device_resume_noirq(dev, state);
> - if (error) {
> - suspend_stats.failed_resume_noirq++;
> - dpm_save_failed_step(SUSPEND_RESUME_NOIRQ);
> - dpm_save_failed_dev(dev_name(dev));
> - pm_dev_err(dev, state, " noirq", error);
> + if (!is_async(dev)) {
> + int error;
> +
> + error = device_resume_noirq(dev, state, false);
> + if (error) {
> + suspend_stats.failed_resume_noirq++;
> + dpm_save_failed_step(SUSPEND_RESUME_NOIRQ);
> + dpm_save_failed_dev(dev_name(dev));
> + pm_dev_err(dev, state, " noirq", error);
> + }
> }
>
> mutex_lock(&dpm_list_mtx);
> put_device(dev);
> }
> mutex_unlock(&dpm_list_mtx);
> + async_synchronize_full();
> dpm_show_time(starttime, state, "noirq");
> resume_device_irqs();
> cpuidle_resume();
> @@ -742,12 +782,6 @@ static void async_resume(void *data, async_cookie_t cookie)
> put_device(dev);
> }
>
> -static bool is_async(struct device *dev)
> -{
> - return dev->power.async_suspend && pm_async_enabled
> - && !pm_trace_is_enabled();
> -}
> -
> /**
> * dpm_resume - Execute "resume" callbacks for non-sysdev devices.
> * @state: PM transition of the system being carried out.
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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