PM: Add a switch for disabling/enabling asynchronous suspend/resume

[sfrench/cifs-2.6.git] / Documentation / ABI / testing / sysfs-power

diff --git a/Documentation/ABI/testing/sysfs-power b/Documentation/ABI/testing/sysfs-power
index d882f8093871386f03ab63c6cc2b820adb2610e6..d6a801f45b484e4df433ff09e85a6f3bc07707d5 100644 (file)
--- a/Documentation/ABI/testing/sysfs-power
+++ b/Documentation/ABI/testing/sysfs-power
@@ -21,7 +21,7 @@ Description:
                these states.
 
 What:          /sys/power/disk
-Date:          August 2006
+Date:          September 2006
 Contact:       Rafael J. Wysocki <rjw@sisk.pl>
 Description:
                The /sys/power/disk file controls the operating mode of the
@@ -39,6 +39,19 @@ Description:
                'reboot' - the memory image will be saved by the kernel and
                the system will be rebooted.
 
+               Additionally, /sys/power/disk can be used to turn on one of the
+               two testing modes of the suspend-to-disk mechanism: 'testproc'
+               or 'test'.  If the suspend-to-disk mechanism is in the
+               'testproc' mode, writing 'disk' to /sys/power/state will cause
+               the kernel to disable nonboot CPUs and freeze tasks, wait for 5
+               seconds, unfreeze tasks and enable nonboot CPUs.  If it is in
+               the 'test' mode, writing 'disk' to /sys/power/state will cause
+               the kernel to disable nonboot CPUs and freeze tasks, shrink
+               memory, suspend devices, wait for 5 seconds, resume devices,
+               unfreeze tasks and enable nonboot CPUs.  Then, we are able to
+               look in the log messages and work out, for example, which code
+               is being slow and which device drivers are misbehaving.
+
                The suspend-to-disk method may be chosen by writing to this
                file one of the accepted strings:
 
@@ -46,6 +59,8 @@ Description:
                'platform'
                'shutdown'
                'reboot'
+               'testproc'
+               'test'
 
                It will only change to 'firmware' or 'platform' if the system
                supports that.
@@ -86,3 +101,16 @@ Description:
 
                CAUTION: Using it will cause your machine's real-time (CMOS)
                clock to be set to a random invalid time after a resume.
+
+What:          /sys/power/pm_async
+Date:          January 2009
+Contact:       Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+               The /sys/power/pm_async file controls the switch allowing the
+               user space to enable or disable asynchronous suspend and resume
+               of devices.  If enabled, this feature will cause some device
+               drivers' suspend and resume callbacks to be executed in parallel
+               with each other and with the main suspend thread.  It is enabled
+               if this file contains "1", which is the default.  It may be
+               disabled by writing "0" to this file, in which case all devices
+               will be suspended and resumed synchronously.