From: Arjan van de Ven <arjan@linux.intel.com>
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@linux.intel.com>
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
@@ -123,6 +123,45 @@ int pm_runtime_idle(struct device *dev)
}
EXPORT_SYMBOL_GPL(pm_runtime_idle);
+
+/**
+ * update_pm_runtime_accounting - Update the time accounting of power states
+ * @dev: Device to update the accounting for
+ *
+ * In order to be able to have time accounting of the various power states
+ * (as used by programs such as PowerTOP to show the effectiveness of runtime
+ * PM), we need to track the time spent in each state.
+ * update_pm_runtime_accounting must be called each time before the
+ * runtime_status field is updated, to account the time in the old state
+ * correctly.
+ */
+void update_pm_runtime_accounting(struct device *dev)
+{
+ unsigned long now = jiffies;
+ int delta;
+
+ delta = now - dev->power.accounting_timestamp;
+
+ if (delta < 0)
+ delta = ...
