Standby and suspend on memory

http://www.stlinux.com/advanced/power-management/features/standby
http://www.stlinux.com/advanced/power-management/features

• CPU frequency scaling
• Standby and suspend on memory
• Sleep on idle
• Dynamic tick
• Hibernation on media

The Linux power management subsystem shows a unified sysfs interface to userspace.The interface exists in /sys/power/ directory.
The file: /sys/power/state controls the system power state.A reading from this file, will return what states are supported, which are hard-coded to:

• standby (Power-On Suspend),
• mem (Power-On Suspend-to-RAM)
• disk (Power-Off Suspend-to-Disk)

To add the standby and suspend on memory support in the kernel it is necessary to enable:

 Power management option ---> Power management support
 Power management option ---> Suspend to RAM and standby

To enter in standby type on the available target:

 target# echo -n standby > /sys/pm/state

To enter in suspend on memory type on the available target:

   target# echo -n mem > /sys/pm/state

Bibliography

• Linux Symposium 2002: The Linux Kernel Device Model
• Linux Symposium 2003: Linux Kernel Power Management
• Linux Symposium 2005: The sysfs Filesystem
• Linux Symposium 2008: Suspend-to-RAM in Linux
• Linux Kernel Weekly: A new suspend/hibernate infrastructure