2016-6-27 Study Summary

Common load Command top, W, uptime

W's load average shows the average CPU usage value for 1 minutes, 5 minutes, 15 minutes.

See the number of cores in the CPU using the command cat/proc/cpuinfo The value of the option processor , 0 represents the single core CPU.

When the load is high, the average value exceeds the total number of cores, or close to the total number of cores.

Actual work environment, see the values within one minute.

Uptime The actual usage is the same as W , and the content shown is the same.

Top can dynamically display the use of the machine, can contain W or uptime display content, and is real-time, the main view of the CPU utilization of individual programs, see the most CPU-intensive, memory programs, exit top using the Q keyboard, you can do some work on the PID, The default is 3 seconds to refresh, parameter-D can specify the refresh time, the time unit is seconds,-C can let the command display more comprehensive,-BN1 can view the system information at once, not dynamic refresh.

Vmstat By default, you can specify the parameter Num1 num, NUM1 is the display for a few seconds, num2 is the number of times to show, R indicates how many tasks are running, how many processes are in use cpu,b in a second, blocking means that the disk I/O is blocked, If the bandwidth is full, the process will also be blocked, primarily referring to the CPU's us, which describes the CPU usage of a process.

SAR default is not installed, need to install the command is yum install Sysstat-y, the main view network card traffic, the method is sar-n DEV, can view historical traffic, with command sar-n dev-f view the files that begin with /var/log/sa/saxxx .

Free View Memory The main information is how much memory, how much memory is used, how much memory is left, and the actual remaining memory is the sum of buffer plus cached.

PS View all processes in the system main usage-aux or-elf parameter specific meaning can refer to http://man.linuxde.net/ps the specific parameters of this page. Often used with pipeline command |grep to see if the process is running.

2016-6-27 Study Summary