Linux Preformance Analyze CPU(二) - Linux性能分析之CPU

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// IO密集型，执行write()/unlink()，iowait模拟，导致%iowait很高
stress -d 2 --timeout 600 -v

// CPU密集型, 执行sqrt()，导致%usr很高
stress -c 2 --timeout 600 -v

// IO密集型，执行sync()，模拟执行磁盘IO刷新，导致%sys系统调用很高
stress -i 2 --timeout 600 -v

// 执行malloc()/free()，模拟内存申请释放，导致%sys系统调用很高
stress -m 2 --timeout 600 -v

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// 系统负载
 # watch -d uptime
...,  load average: 1.00, 0.75, 0.39

// cpu状态
 # mpstat 2
12:29:02 AM  CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest  %gnice   %idle
12:29:04 AM  all    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
12:29:06 AM  all    0.00    0.00    0.50    0.00    0.00    0.00    0.00    0.00    0.00   99.50
12:29:08 AM  all    0.50    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00   99.50

// 进程状态
 # pidstat
12:30:12 AM   UID       PID    %usr %system  %guest    %CPU   CPU  Command
12:30:14 AM     0     13727    0.00    0.50    0.00    0.50     0  pidstat

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// 以 10 个线程运行 5 分钟的基准测试，模拟多线程切换的问题
$ sysbench --threads=10 --max-time=300 threads run

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// 关注system的in（中断）和cs（系统上下文切换），cpu的us（用户态）和sy（内核态），更多含义man vmstat
vmstat 1 
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 1  0      0 737980   7664 157964    0    0     0     0   31   31  0  1 99  0  0
 
// cat /proc/interrupts

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// cswch/s : voluntary context switches(自愿切换，IO阻塞资源等待，进程自动放弃CPU资源)
     Total number of voluntary context switches the task made per  sec‐
     ond.  A voluntary context switch occurs when a task blocks because
     it requires a resource that is unavailable.

// nvcswch/s : non voluntary context switches（非自愿切换，时间片用完被OS调度走）
     Total number of non voluntary context switches the task  made  per
     second.  A involuntary context switch takes place when a task exe‐
     cutes for the duration of its time slice and  then  is  forced  to
     relinquish the processor.

// -w表示查看上下文切换，-t表示任务关联的线程
pidstat -wt 1
Average:      UID      TGID       TID   cswch/s nvcswch/s  Command
Average:        0         1         -      0.50      0.00  systemd
Average:        0         -         1      0.50      0.00  |__systemd
Average:        0         3         -      1.99      0.00  ksoftirqd/0
Average:        0         -         3      1.99      0.00  |__ksoftirqd/0