Linux Commands View server performance

1 uptime

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1. Current Time 13:02:42

2. The system has been running for days, 19:00

3. 2 users online currently

4. Average load: 0.43, 0.25, 0.23, last 1 minutes, 5 minutes, 15 minutes load of the system

In general, the current number of active processes per CPU core is not greater than 3, the system performance is good! Of course, it is said that each CPU core, that is, if your host is a quad-core CPU, then as long as the uptime last output of a string of characters less than 12 means that the system load is not very serious.

2 Vmstat 8 refreshes every 8 seconds

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The output is interpreted as follows:

1) procs

A.R column represents the number of processes running and waiting for CPU time slices, if the long-term is greater than the number of system CPUs, it indicates that CPU resources are insufficient, you can consider increasing the CPU;

The b.b column represents the number of processes waiting on a resource, such as waiting for I/O or memory exchange.

2) Memory

The A.SWPD column represents the amount of memory (in kilobytes) that is switched to the memory swap area. If the value of SWPD is not 0 or larger, and the value of Si, so long 0, then this situation generally do not have to worry about, will not affect the system performance;

The B.free column represents the amount of physical memory currently idle in kilobytes (KB);

The C.buff column represents the amount of memory buffers cache, which is generally required to read and write to the block device.

The D.cache column represents the amount of memory for page cached, which is generally used as the cached of the file system, and frequently accessed files are cached. If the cached value is large, it indicates that there are many cached files. If the bi in IO is small in this case, the file system is more efficient.

3) Swap

The A.si column indicates the amount of memory that is being transferred from the disk into the memory swap area;

The b.so column represents the amount of memory that is called into the disk, which is the memory swap area

C. In general, the values of Si and so are 0, if the value of Si and so is not 0 for a long time, it indicates that the system memory is not enough and needs to consider whether to increase system memory.

4) IO

The A.bi column represents the total amount of data read from the block device (that is, read disk, Unit kb/sec)

B.bo column indicates the total amount of data written to the block device (that is, write disk, Unit kb/sec)

The Bi+bo reference value set here is 1000, if more than 1000, and the WA value is larger, it represents the system disk IO performance bottleneck.

5) system

The a.in column represents the number of device interrupts per second observed in a time interval;

The B.cs column represents the number of context switches produced per second.

The higher these two values are, the more CPU time the kernel consumes.

6) CPU

The a.us column shows the percentage of time that the user process consumes the CPU. When the value of us is higher, it indicates that the user process consumes more CPU time, if the long-term greater than 50%, need to consider the optimizer what.

The B.sy column shows the percentage of time that the kernel process consumes the CPU. When the value of SY is higher, it indicates that the kernel consumes more CPU time, and if Us+sy exceeds 80%, it indicates that there is insufficient CPU resources.

The C.id column shows the percentage of time the CPU is in idle state;

The D.wa column represents the percentage of CPU time that the IO wait occupies. The higher the WA value, the more serious the IO waits. If the WA value exceeds 20%, the IO wait is severe.

The E.st column is generally not concerned with the percentage of time that the virtual machine occupies. (Linux 2.6.11)

3 Top

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Press 1 to view each CPU

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Shift+p CPU Sequencing

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Shift+m Memory Sequencing

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4 free-m Unit is M

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This article is from the "Ideal for Life" blog, please be sure to keep this source http://lampol.blog.51cto.com/11662628/1854552

Linux Commands View server performance