On Saturday, July 10, 2010, Arjan van de Ven wrote:
> From: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
> Subject: [PATCH v2] pm: Add runtime PM statistics
>
> In order for PowerTOP to be able to report how well the new runtime PM is working
> for the various drivers, the kernel needs to export some basic statistics in sysfs.
>
> This patch adds two sysfs files in the runtime PM domain that expose the
> total time a device has been active, and the time a device has been suspended.
>
> With this PowerTOP can compute the activity percentage
>
> Active %age = 100 * (delta active) / (delta active + delta suspended)
>
> and present the information to the user.
>
> I've written the PowerTOP code (slated for version 1.12) already, and the output looks
> like this:
>
> Runtime Device Power Management statistics
> Active Device name
> 10.0% 06:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8101E/RTL8102E PCI Express Fast Ethernet controller
>
>
>
> [version 2: fix stat update bugs noticed by Alan Stern]
>
> Signed-off-by: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
>
> diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
> index b0ec0e9..b78c401 100644
> --- a/drivers/base/power/runtime.c
> +++ b/drivers/base/power/runtime.c
...
>
> +static ssize_t rtpm_active_time_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + int ret;
> + spin_lock_irq(&dev->power.lock);
> + update_pm_runtime_accounting(dev);
> + ret = sprintf(buf, "%i\n", jiffies_to_msecs(dev->power.active_jiffies));
> + spin_unlock_irq(&dev->power.lock);
> + return ret;
> +}
> +
> +static ssize_t rtpm_suspended_time_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + int ret;
> + spin_lock_irq(&dev->power.lock);
> + update_pm_runtime_accounting(dev);
> + ret = sprintf(buf, "%i\n",
> + jiffies_to_msecs(dev->power.suspended_jiffies));
> + spin_unlock_irq(&dev->power.lock);
> + return ret;
> +}
> +
> static DEVICE_ATTR(runtime_usage, 0444, rtpm_usagecount_show, NULL);
> static DEVICE_ATTR(runtime_active_kids, 0444, rtpm_children_show, NULL);
> static DEVICE_ATTR(runtime_status, 0444, rtpm_status_show, NULL);
> +static DEVICE_ATTR(runtime_active_time, 0444, rtpm_active_time_show, NULL);
> +static DEVICE_ATTR(runtime_suspended_time, 0444, rtpm_suspended_time_show, NULL);
> static DEVICE_ATTR(runtime_enabled, 0444, rtpm_enabled_show, NULL);
On a second thought, "active_time" and "suspended_time" should be sufficient
(ie. the "runtime_" prefix is not really necessary).
Rafael
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