开发板启动时间优化

1. 查看启动log，分析处理时间长的信息，如下是优化前的log

[    5.617156] Run /init as init process
chmod: /lib32/*: No such file or directory
[    5.686178] ubi2: attaching mtd2
[    9.176987] ubi2: scanning is finished
[    9.194554] ubi2: attached mtd2 (name "sdcard", size 384 MiB)
[    9.200413] ubi2: PEB size: 131072 bytes (128 KiB), LEB size: 126976 bytes
[    9.207305] ubi2: min./max. I/O unit sizes: 2048/2048, sub-page size 2048
[    9.214108] ubi2: VID header offset: 2048 (aligned 2048), data offset: 4096
[    9.221084] ubi2: good PEBs: 3072, bad PEBs: 0, corrupted PEBs: 0
[    9.227191] ubi2: user volume: 1, internal volumes: 1, max. volumes count: 128
[    9.234434] ubi2: max/mean erase counter: 7/4, WL threshold: 4096, image sequence number: 194771927
[    9.243494] ubi2: available PEBs: 873, total reserved PEBs: 2199, PEBs reserved for bad PEB handling: 80
[    9.253011] ubi2: background thread "ubi_bgt2d" started, PID 124
[    9.257213] UBIFS (ubi2:0): Mounting in unauthenticated mode
[    9.264962] UBIFS (ubi2:0): background thread "ubifs_bgt2_0" started, PID 126
[    9.312552] UBIFS (ubi2:0): recovery needed
[    9.488160] UBIFS (ubi2:0): recovery completed
[    9.492791] UBIFS (ubi2:0): UBIFS: mounted UBI device 2, volume 0, name "nvrp1"
[    9.500134] UBIFS (ubi2:0): LEB size: 126976 bytes (124 KiB), min./max. I/O unit sizes: 2048 bytes/2048 bytes
[    9.510065] UBIFS (ubi2:0): FS size: 266903552 bytes (254 MiB, 2102 LEBs), journal size 13332480 bytes (12 MiB, 105 LEBs)
[    9.521035] UBIFS (ubi2:0): reserved for root: 4952683 bytes (4836 KiB)
[    9.527668] UBIFS (ubi2:0): media format: w5/r0 (latest is w5/r0), UUID 4C9F6979-6593-4869-B2F5-7A40518C5172, small LPT model
Running sysctl: OK
[    9.569713] random: sshd: uninitialized urandom read (32 bytes read)
[    9.685180] sshd (140): /proc/140/oom_adj is deprecated, please use /proc/140/oom_score_adj instead.
rmmod: remove 'sdk_linuxum': No such file or directory
[   13.487545] sdk_linuxum: loading out-of-tree module taints kernel.
[   13.501830] [Kernel: hal_ki_device_chip_id_get - 1209] GET PCI bus num: 65535
[   13.509011] [Kernel: hal_ki_device_chip_id_get - 1236] PCI bus num: 65535, chip_id: 0
[   13.516924] [Kernel: hal_ki_axi_init - 1587] Found chip, name linux-kernel-device0, vendor 0x1619, device 0x2025

1> 发现 attach mtd2 用了3.5秒；2> sshd 的时间较长

然后分析发现 mtd2  分区是325M，创建的卷是256MB, 实际上 该分区只需要 50MB的卷就可以了； 然后查看rcS文件，发现sshd 启动之后又 sleep了2秒

修改之后

[    5.695666] ubi2: attaching mtd2
[    6.282209] ubi2: scanning is finished
[    6.296197] ubi2: attached mtd2 (name "sdcard", size 64 MiB)
[    6.301887] ubi2: PEB size: 131072 bytes (128 KiB), LEB size: 126976 bytes
[    6.308778] ubi2: min./max. I/O unit sizes: 2048/2048, sub-page size 2048
[    6.315580] ubi2: VID header offset: 2048 (aligned 2048), data offset: 4096
[    6.322554] ubi2: good PEBs: 512, bad PEBs: 0, corrupted PEBs: 0
[    6.328574] ubi2: user volume: 1, internal volumes: 1, max. volumes count: 128
[    6.335813] ubi2: max/mean erase counter: 8/3, WL threshold: 4096, image sequence number: 679267095
[    6.344873] ubi2: available PEBs: 15, total reserved PEBs: 497, PEBs reserved for bad PEB handling: 80
[    6.354215] ubi2: background thread "ubi_bgt2d" started, PID 123
[    6.358268] UBIFS (ubi2:0): Mounting in unauthenticated mode
[    6.366191] UBIFS (ubi2:0): background thread "ubifs_bgt2_0" started, PID 125
[    6.414243] UBIFS (ubi2:0): recovery needed
[    6.559462] UBIFS (ubi2:0): recovery completed
[    6.564072] UBIFS (ubi2:0): UBIFS: mounted UBI device 2, volume 0, name "nvrp1"
[    6.571402] UBIFS (ubi2:0): LEB size: 126976 bytes (124 KiB), min./max. I/O unit sizes: 2048 bytes/2048 bytes
[    6.581336] UBIFS (ubi2:0): FS size: 51171328 bytes (48 MiB, 403 LEBs), journal size 2539520 bytes (2 MiB, 20 LEBs)
[    6.591784] UBIFS (ubi2:0): reserved for root: 2416947 bytes (2360 KiB)
[    6.598417] UBIFS (ubi2:0): media format: w5/r0 (latest is w5/r0), UUID A867C717-017F-4254-9A6D-B1D41C6DB060, small LPT model
/dev/ubi2_0 do exist, so do nothing
Running sysctl: OK