Ubuntu12.10 launch time survey

Ubuntu12.10 launch time investigation recently Ubuntu system was used for a period of time, it was found that the system started slowly, just started for about half a minute when the system was installed, and now it seems that the start time is almost one minute, so I decided to investigate. First, Google, and found that the Internet wants to accelerate Ubuntu startup... ubuntu12.10 launch time investigation recently Ubuntu system was used for a period of time, it was found that the system started slowly, just started for about half a minute when the system was installed, and now it seems that the start time is almost one minute, so I decided to investigate. First, Google will find many posts on the Internet that want to accelerate the startup of Ubuntu. First, we recommend a bootchart tool, which can record the startup process of the Ubuntu system and provide graphical display, then install dev @ devhost :~ $ Sudo apt-get install after bootchart is installed, restart the machine system, and view it in the/var/log/bootchart/logs file. the startup process consists of the following three parts: 1) 0 ~ 15 seconds: IO-intensive, relatively idle CPU. from the process descriptions below, it is estimated that the kernel is mounted to the file system and disk detection; 2) 15 ~ 35 seconds: I/O is idle, and the CPU is also idle. here we can see that ifup, bridge, and ifconfig are mainly related to the network, this time actually takes 20 seconds (note that I made it in my laptop, as well as wireless devices); 3) 35 ~ 55 seconds: I/O starts to become intensive and CPU intensive. There are many things in this phase, including network management services, login services, and desktops, I also used the dmesg command to look at it, from the time can basically prove the above three stages of doing: [2.275412] EXT4-fs (sda7): mounted filesystem with ordered data mode. opts: (null) [11.478634] Adding 4083708 k swap on/dev/sda5. Priority:-1 extents: 1 small SS: 4083708 k [11.526044] IPv6: ADDRCONF (NETDEV_UP): eth0: link is not ready [11.639571] udevd [479]: starting version 175 [11.762504] lp: driver loa Ded but no devices found [12.072290] EXT4-fs (sda7): re-mounted. opts: errors = remount-ro 2nd seconds inverted 12 seconds related to mount; [14.814577] br0: port 1 (eth0) entered listening state [14.814587] br0: port 1 (eth0) entered listening state [23.797215] br0: port 1 (eth0) entered learning state [32.800776] br0: topology change detected, propagating [32.800805] br0: port 1 (eth0) entered forwarding state: 14th seconds, 32 seconds, and the network is switched off. It depends on the br0 I set (Bridge, which I used to experiment with virtual machine networks. So, I temporarily removed the bridge. After I started it again, I found that the 2nd phase was as follows: [11.526044] IPv6: ADDRCONF (NETDEV_UP): eth0: link is not ready... [16.317051] r8169. 0:> eth0: link up means no bridge is needed. it takes less than five seconds for the network to get up. Therefore, I recently started the Ubuntu system because of the bridge settings. In addition, we also learned that if you need to further reduce the start time, then: 1. SSD hard disks are used. to reduce the I/O-intensive operations in stages 1st and 3rd, the main bottleneck lies in disk I/O read/write. Therefore, only SSD hard disks can be replaced. 2. you can install the bum tool to manage services and disable unnecessary services (but be careful that the system may fail to start if necessary services are disabled ).