How can i reduce system boot time?

Maxn
Hi,
I m using my 2.6.31 kernel (customized) and a jffs2 file system on
mini2440.
For my project i need to boot kernel as early as possible. (within 30secs)

I observed that , while booting kernel 

1) s3c2410-rtc s3c2410-rtc: setting system clock to 2009-11-25 07:03:08 
UTC (1259132588)            //takes 4-5 seconds

2) VFS: Mounted root (jffs2 filesystem) on device 31:3.
Freeing init memory: 124K   //takes 9-10 seconds

The boot process is :-

Starting kernel ...

Uncompressing
Linux...........................................................................
...............................
Linux version 2.6.31.1 (gautam@gautam-desktop) (gcc version 4.3.2 (Sourcery
G++ Lite 2008q3-72) ) #5 Wed Nov 25 19:11:32 IST9
CPU: ARM920T [41129200] revision 0 (ARMv4T), cr=c0007177
CPU: VIVT data cache, VIVT instruction cache
Machine: MINI2440
Memory policy: ECC disabled, Data cache writeback
CPU S3C2440A (id 0x32440001)
S3C24XX Clocks, (c) 2004 Simtec Electronics
S3C244X: core 405.000 MHz, memory 101.250 MHz, peripheral 50.625 MHz
CLOCK: Slow mode (1.500 MHz), fast, MPLL on, UPLL on
Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 16256
Kernel command line: root=/dev/mtdblock3 rootfstype=jffs2
console=ttySAC0,115200
PID hash table entries: 256 (order: 8, 1024 bytes)
Dentry cache hash table entries: 8192 (order: 3, 32768 bytes)
Inode-cache hash table entries: 4096 (order: 2, 16384 bytes)
Memory: 64MB = 64MB total
Memory: 60852KB available (3376K code, 411K data, 124K init, 0K highmem)
SLUB: Genslabs=11, HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
NR_IRQS:85
irq: clearing pending status 02000000
irq: clearing subpending status 00000003
irq: clearing subpending status 00000002
Console: colour dummy device 80x30
console [ttySAC0] enabled
Calibrating delay loop... 201.93 BogoMIPS (lpj=504832)
Mount-cache hash table entries: 512
CPU: Testing write buffer coherency: ok
NET: Registered protocol family 16
MINI2440: Option string mini2440=0tb
MINI2440: LCD [0:240x320] 1:800x480 2:1024x768
S3C2440: Initialising architecture
S3C2440: IRQ Support
S3C24XX DMA Driver, (c) 2003-2004,2006 Simtec Electronics
DMA channel 0 at c4808000, irq 33
DMA channel 1 at c4808040, irq 34
DMA channel 2 at c4808080, irq 35
DMA channel 3 at c48080c0, irq 36
S3C244X: Clock Support, DVS off
bio: create slab <bio-0> at 0
usbcore: registered new interface driver usbfs
usbcore: registered new interface driver hub
usbcore: registered new device driver usb
s3c-i2c s3c2440-i2c: slave address 0x10
s3c-i2c s3c2440-i2c: bus frequency set to 98 KHz
s3c-i2c s3c2440-i2c: i2c-0: S3C I2C adapter
NET: Registered protocol family 2
IP route cache hash table entries: 1024 (order: 0, 4096 bytes)
TCP established hash table entries: 2048 (order: 2, 16384 bytes)
TCP bind hash table entries: 2048 (order: 1, 8192 bytes)
TCP: Hash tables configured (established 2048 bind 2048)
TCP reno registered
NET: Registered protocol family 1
JFFS2 version 2.2. (NAND) © 2001-2006 Red Hat, Inc.
ROMFS MTD (C) 2007 Red Hat, Inc.
msgmni has been set to 118
alg: No test for stdrng (krng)
io scheduler noop registered
io scheduler anticipatory registered (default)
io scheduler deadline registered
io scheduler cfq registered
Console: switching to colour frame buffer device 60x53
fb0: s3c2410fb frame buffer device
s3c2440-uart.0: ttySAC0 at MMIO 0x50000000 (irq = 70) is a S3C2440
s3c2440-uart.1: ttySAC1 at MMIO 0x50004000 (irq = 73) is a S3C2440
s3c2440-uart.2: ttySAC2 at MMIO 0x50008000 (irq = 76) is a S3C2440
brd: module loaded
at24 0-0050: 1024 byte 24c08 EEPROM (writable)
dm9000 Ethernet Driver, V1.31
eth0: dm9000e at c486e300,c4872304 IRQ 51 MAC: 08:08:11:18:12:27 (chip)
S3C24XX NAND Driver, (c) 2004 Simtec Electronics
s3c24xx-nand s3c2440-nand: Tacls=1, 9ns Twrph0=3 29ns, Twrph1=2 19ns
s3c24xx-nand s3c2440-nand: NAND soft ECC
NAND device: Manufacturer ID: 0xec, Chip ID: 0x76 (Samsung NAND 64MiB 3,3V
8-bit)
Creating 4 MTD partitions on "NAND 64MiB 3,3V 8-bit":
0x000000000000-0x000000040000 : "u-boot"
ftl_cs: FTL header not found.
0x000000040000-0x000000060000 : "u-boot-env"
ftl_cs: FTL header not found.
0x000000060000-0x000000560000 : "kernel"
ftl_cs: FTL header not found.
0x000000560000-0x000004000000 : "root"
ftl_cs: FTL header not found.
ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver
s3c2410-ohci s3c2410-ohci: S3C24XX OHCI
s3c2410-ohci s3c2410-ohci: new USB bus registered, assigned bus number 1
s3c2410-ohci s3c2410-ohci: irq 42, io mem 0x49000000
usb usb1: configuration #1 chosen from 1 choice
hub 1-0:1.0: USB hub found
hub 1-0:1.0: 2 ports detected
usbcore: registered new interface driver libusual
s3c2440-usbgadget s3c2440-usbgadget: S3C2440: increasing FIFO to 128 bytes
mice: PS/2 mouse device common for all mice
input: gpio-keys as /devices/platform/gpio-keys/input/input0
s3c2440-ts s3c2440-ts: Starting
  Created group ts filter len 12 depth 2 close 10 thresh 6
  Created Median ts filter len 20 depth 2 dec 24
  Created Mean ts filter len 4 depth 2 thresh 65535
  Created Linear ts filter depth 2
s3c2440-ts s3c2440-ts: 4 filter(s) initialized
s3c2440-ts s3c2440-ts: successfully loaded
input: s3c2410 TouchScreen as /devices/virtual/input/input1
S3C24XX RTC, (c) 2004,2006 Simtec Electronics
s3c2410-rtc s3c2410-rtc: rtc disabled, re-enabling
s3c2410-rtc s3c2410-rtc: rtc core: registered s3c as rtc0
i2c /dev entries driver
S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics
s3c2410-wdt s3c2410-wdt: watchdog inactive, reset disabled, irq enabled
cpuidle: using governor ladder
sdhci: Secure Digital Host Controller Interface driver
sdhci: Copyright(c) Pierre Ossman
mapped channel 0 to 0
s3c2440-sdi s3c2440-sdi: powered down.
s3c2440-sdi s3c2440-sdi: initialisation done.
Registered led device: led1
Registered led device: led2
Registered led device: led3
Registered led device: led4
Registered led device: backlight
usbcore: registered new interface driver hiddev
usbcore: registered new interface driver usbhid
usbhid: v2.6:USB HID core driver
TCP cubic registered
NET: Registered protocol family 17
RPC: Registered udp transport module.
RPC: Registered tcp transport module.
s3c2410-rtc s3c2410-rtc: setting system clock to 2009-11-25 07:03:08 UTC
(1259132588)       
Empty flash at 0x0191516c ends at 0x01915200
VFS: Mounted root (jffs2 filesystem) on device 31:3.
Freeing init memory: 124K                   

Please press Enter to activate this console.

Any suggestions??

gene.sally
Hi,

>> jffs2 filesystem

This is your culprit.  You can either switch to yaffs2, use a read-only
file system for the RFS, or use sumtool to create a summary for faster
jffs2 mounting.

The least impact is using sumtool
(http://www.linux-mtd.infradead.org/doc/jffs2.html) because your RFS will
still be read/write and you won't have to be particular about making sure
your programs don't want to write somewhere that you thought was writeable
by default.

Regards,
gene