1. Power Management Discussion
Hiroki Kaminaga
Sony Corporation
[translated by
2005/Sept/30
JapanTechnicalJamboree4

2. JapanTechnicalJamboree4
Goal :
Want to shorten start up time of application HW
Initialization
Mounting
drivers
init
Startup time of application
(Boot loader
/ kernel)
1 [s]
1 [s]
2 [s]
5 [s]
Processing until the application reaches to main()
Transfer of image
Dynamic linking
Global constructors
IPC Processing among applications for the whole system running
2005/Sept/30
JapanTechnicalJamboree4

3. Conventional Approaches:
Reduce dynamic linking time
prelink
Reduce time for global constructors
Put constructors in the same place(Localization effect)
Execute in place (XIP)
Demand Paging of Data Section(From Mizuyama’s presentation in the previous Jamboree)
2005/Sept/30
JapanTechnicalJamboree4

4. JapanTechnicalJamboree4
Our Approaches:
Use return from hibernation
(1) BIOS (Boot loader) level
(2) Kernel level
(3) BIOS + kernel
1,2,3 の pro/con 図
2005/Sept/30
JapanTechnicalJamboree4

5. Suspend/Resume Sequence(1):
KERNEL
I/O
save
Image
save
I/O
init
Image
restore
I/O
rest.
BOOT
LOADER
OFF ON
2005/Sept/30
JapanTechnicalJamboree4

6. Suspend/Resume Sequence (2):
KERNEL
I/O
save
Image
save
I/O
init
boot
I/O
s.d.
Image
restore
I/O
rest.
BOOT
LOADER
OFF ON
2005/Sept/30
JapanTechnicalJamboree4

7. Suspend/Resume Sequence (3):
KERNEL
I/O
save
img
save
I/O
init
img
rest
I/O
rest.
I/O
save
img
save
I/O
init
img
rest
　I/O
　rest.
BOOT
LOADER
BOOT
LOADER
OFF ON
2005/Sept/30
JapanTechnicalJamboree4

8. Comparison of Three Approaches:
(1) BIOS (Boot loader) level
Relatively faster resume from hibernation
Complicated processing required when data integrity lost
(2) Kernel level
Can process to ensure the data integrity after resume from hibernation
Slower resume from hibernation
(3) BIOS + kernel
Fast resume from hibernation
Can process to ensure the data integrity
1,2,3 の pro/con 図
2005/Sept/30
JapanTechnicalJamboree4

9. JapanTechnicalJamboree4
Basic ideas:
Startup
Reduce processing until the un-hibernate on kernel side, using helper function of Boot loader
DEFERRED_RESUME
Start up the specified application with high priority
Saving system image
To start always with the same state
Others
Mount
Splash window
High speed shutdown
2005/Sept/30
JapanTechnicalJamboree4

10. JapanTechnicalJamboree4
Hibernation on Linux:
Swsusp
Included in 2.6 vanilla kernel (Documentation/power/swsusp.txt)
Author: Pavel Machek
Software suspend 2
Author: Nigel Cunningham
2005/Sept/30
JapanTechnicalJamboree4

11. Hibernate on Linux(comparison):
swsusp
suspend2
architecture
i386, ppc, x86_64, ia64
i386, ppc, x86_64
Discontiguous memory ○ ×
Compression
Encryption
Suspend-to-swapfile
Suspend-to-file
Userland サポート
Source：　
2005/Sept/30
JapanTechnicalJamboree4

12. JapanTechnicalJamboree4
Environment:
Target board
OMAP Starter Kit (OSK 5912) OS
Linux 2.6
Boot loader
U-boot
Hardware Features:
ARM9 core operating at 192 Mhz.
DSP core operating at 192 Mhz.
TLV320AIC23 Stereo Codec
32 Mbyte DDR SDRAM
32 Mbyte Flash ROM
RS-232 Serial Port
10 MBPS Ethernet port
USB Host Port
Compact flash connector
On board IEEE JTAG
2005/Sept/30
JapanTechnicalJamboree4

13. JapanTechnicalJamboree4
Work Items:
Choosing hibernation on Linux
Trying with swsusp first
Porting to ARM
Hibernation onto FLASH
Saving system image
High speed shutdown
Hibernation on Boot loader
DEFERED_RESUME
2005/Sept/30
JapanTechnicalJamboree4

14. JapanTechnicalJamboree4
Current status:
Investigating Suspend2
Compression of system image
Encryption of system image
Porting Suspend2 onto ARM
Investigating U-boot
Hibernation on Boot loader side
2005/Sept/30
JapanTechnicalJamboree4

15. JapanTechnicalJamboree4
Demo:
2005/Sept/30
JapanTechnicalJamboree4

16. JapanTechnicalJamboree4
Community:
Sent ARM port patch to Suspend2 ML; Accepted favarably.
ARM ML adviced me on questions/issues
Thread URL など
2005/Sept/30
JapanTechnicalJamboree4

17. JapanTechnicalJamboree4
EOF
2005/Sept/30
JapanTechnicalJamboree4

18. Congraturation! HanshinTigers won the league championship
2005/Sept/30
JapanTechnicalJamboree4