The authoritative guide to Java Performance Optimization-reading notes (i)-operating System performance monitoring tool

One: CPU

1. The user-state CPU is the percentage of the total CPU time that executes the application code.

The system-State CPU is the percentage of the total CPU time that the application performs operating system calls. System-State CPU high means that shared resources are competing or there is a lot of interaction between I/O devices.

One goal of improving application performance and scalability is to minimize system-state CPU usage.

2. The CPU run queue is a lightweight process that is ready to run and waiting for available CPUs.

When the running queue length reaches 4 of the processor or more, the corresponding system is very slow.

There are two ways to resolve the run queue Length:

1). Increase the CPU to share the load;

2). Analyze the application running in the system, improve the CPU utilization;

1. Vmstat

procs-----------Memory-------------Swap-------io-----system--------CPU-----r  B   swpd   free   buff  cache   si   so    bi    bo   in   CS US sy ID WA St 2  0      0 104956    868 825812    0    0     1     5  0  0  0 0

R:cpu Run Queue Length, value is the actual number of lightweight processes in the running queue

US: User-State CPU utilization

SY: System State CPU usage

ID:CPU Idle Rate

2. Top

top-09:42:04 up 3 days, 3 min, 1 user, load average:0.00, 0.01, 0.05tasks:108 Total, 3 running, sleeping, 0 Stopped, 0 zombie%cpu (s): 0.0 us, 0.0 sy, 0.0 ni,100.0 ID, 0.0 wa, 0.0 hi, 0.0 si, 0.0 stkib mem:1015472 Total   , 104568 free, 84224 used, 826680 Buff/cachekib swap:0 Total, 0 free, 0 used.                                                                                            727760 avail Mem PID USER PR NI VIRT RES SHR S%cpu%MEM time+ COMMAND 784 root 0 553064 16340 5748 S 0.0 1.6 0:21   . tuned 743 Root 20                                                                                          0 110512 13140 676 S 0.0 1.3 0:00.13 dhclient                                                                9678 polkitd 0 527456 13128 4680 S 0.0 1.3 0:00.09 POLKITD                              1 root 0 43684 6176 3804 S 0.0 0.6 0:05.08 systemd

The upper part is the statistical information of the whole system, and the lower half is the statistics of the process.

Two: Memory

1. When the system is using paging or virtual memory, there is a memory replacement when accessing memory in swap and the JVM garbage collection in swap, there is definitely a problem with performance;

2.

The authoritative guide to Java Performance Optimization-reading notes (i)-operating System performance monitoring tool