From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Chuansheng Liu <chuansheng.liu@intel.com>
Cc: gregkh@linuxfoundation.org, len.brown@intel.com, pavel@ucw.cz,
        linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
        zhuangzhi.li@intel.com
Subject: Re: [PATCH v3 2/5] PM / sleep: Asynchronous threads for resume_noirq
Date: Mon, 17 Feb 2014 18:23:51 +0100
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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@intel.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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