Improvement of bootup time using Power Management Project Update

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Improvement of bootup time using Power Management
- Project Update -

• Hiroki Kaminaga
• Sony Corporation
• kaminaga_at_sm.sony.co.jp
• translated by ikoma_at_slab.tnr.sharpco.jp

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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

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Hibernation on Linux

• Swsusp
• Included in 2.6 vanilla kernel(Documentation/powe
  r/swsusp.txt)
• Author Pavel Machek
• Software Suspend 2
• http//www.suspend2.net/
• Author Nigel Cunningham

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Hibernation on Linux(Comparison)
swsusp
Suspend2
Source http//www.suspend2.net/features
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Current Status

• Ported Suspend2 onto ARM
• Posted on Suspend2 ML
• To be incorporated in next release!

http//lists.suspend2.net/lurker/message/20051114.
094040.11261d0e.en.html
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Environment

• Target board
• OMAP Starter Kit (OSK 5912)
• OS
• Linux 2.6
• Boot loader
• U-boot
• Image destination
• Flash ROM

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 1149.1 JTAG
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Suspend2 Evaluation

• Linux 2.6.14 Suspend2-2.2-rc9
• Hibernate from ash login state
• Used printk time of kernel to measure time
• Baseline is the timimg when linux starts up from
  uboot
• In make menuconfig
• Kernel hacking ---gt Show timing
  information on printks
• http//tree.celinuxforum.org/CelfPubWiki/PrintkTim
  es

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Suspend2 Results

• Normal Start up
• 7.618 sec
• Suspend2 (lzf on)
• 22.492 sec
• 12.371 MB ? 7.450 MB (compression rate 39)
• Suspend2 (lzf off)
• 17.99 sec

Diff of startup time 20, 4.50 sec
Suspend2 process start at 4.402 sec
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swsusp Evaluation

• Linux 2.6.11
• Used printk time of kernel to measure time
• Clock starts when linux starts up from uboot
• In make menuconfig
• Kernel hacking ---gt Show timing
  information on printks
• http//tree.celinuxforum.org/CelfPubWiki/PrintkTim
  es

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swsusp Results

• Normal startup
• 7.676 sec
• swsusp (ash)
• 9.52 sec
• Image 6.38 MB
• swsusp (mplayer)
• 13.910 sec
• Image 10.24 MB

(swsusp process start at 2.174 sec)
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Swsusp/suspend2 Comparison

• Not a strict comparison as Linux versions are not
  the same
• Swsusp/linux2.6.11 image is small, and startup
  is fast
• Suspend2/linux2.6.14 LZF compression of image is
  effective, but tradeoff with startup time
• Suspend2-2.2 is not stable yet, as it is RC

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Swsusp/suspend2 Comparison (cont.)

• Image size/processing time
• Suspend2 925KB/sec
• swsusp 889KB/sec

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Swsusp3

• Author of swsusp, Pavel, has extended swsusp with
  encryption, compression, UI etc.
• The goal is to minimize the change to kernel by
  most of processing done in the user land
• http//lists.osdl.org/pipermail/linux-pm/2005-Sept
  ember/001312.html
• http//lists.osdl.org/pipermail/linux-pm/2005-Nove
  mber/001535.html
• http//lists.osdl.org/pipermail/linux-pm/2005-Nove
  mber/001562.html

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Swsusp3 (ML digests)

• Want to integrate kernel part into around 2.6.16
  (Pavel)
• If integrated, RH/FC kernel would fork. Swsusp3
  uses /dev/mem, but they restrict /dev/mem to
  prevent rootkit (Dave Jones)
• (hot discussion continues on swsusp3 vs
  security)
• Encryption/compression in userland is more
  intuitive (Rafael J. Wysocki )

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Swsusp3 (ML digests (cont.))

• Those functions are already in suspend2.
  Duplicated effort (Dumitru Ciobarcianu )
• It is different to implement in kernel. Cant
  believe Pavel? Nigel knows what he should do to
  work together. (Greg K-H)
• I cant understand why they think userland is the
  right place. (Nigel)

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Swsusp3 (ML digests (cont.))

• Userland swsusp changes only 150 lines or so in
  kernel (Pavel)
• Present Nigels code wont be mainlined. (Greg
  K-H)
• (Hot discussion continues)

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EOF