/android_cpu_usage_calculation

Primary LanguagePythonApache License 2.0Apache-2.0

Android&&Linux Cpu Usage Calculation

整机 cpu 使用率计算

数据来源 ： /proc/stat （具体信息可以参考这里 http://man7.org/linux/man-pages/man5/proc.5.html ）

$ adb shell cat /proc/stat
cpu  24296 3660 18105 899033 640 3576 2202 0 0 0
cpu0 3473 285 3485 105976 58 1911 1120 0 0 0
cpu1 3180 292 3299 110424 75 523 384 0 0 0
cpu2 4209 760 3152 109585 68 501 340 0 0 0
cpu3 3860 790 3005 110329 54 426 276 0 0 0
cpu4 2120 416 1442 115725 100 65 21 0 0 0
cpu5 2015 454 1257 115964 81 74 38 0 0 0
cpu6 3153 394 1358 114858 123 41 10 0 0 0
cpu7 2284 266 1104 116170 78 33 8 0 0 0
intr 2389074 0 0 0 0 492483 0 152708 42 1121 52561 0 0 0 1349 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 6396 15 52113 0 0 0 0 0 0 0 2 0 120654 2800 38 17712 28640 0 716 0 0 0 0 24 0 1957 6038 0 0 0 0 0 0 80 61 76 71 62 61 136 89 13 0 0 0 0 0 0 0 0 16865 0 0 0 0 0 0 0 0 0 0 0 823 0 0 0 0 0 0 0 0 0 0 141 461 0 1 17278 0 0 0 0 0 2289 0 0 0 0 0 0 0 0 0 0 9216 237 0 0 3 0 3 0 0 0 0 0 0 0 0 0 0 2 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 31249 0 0 0 4 0 4554 81 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2233 15 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
ctxt 3555767
btime 1586953851
processes 11046
procs_running 4
procs_blocked 0
softirq 1279600 718 431045 9410 31637 11581 0 106547 338769 0 349893

数据分析

其中第一行 ：cpu 24296 3660 18105 899033 640 3576 2202 0 0 0

参数 解析（单位：jiffies） 原文解释
user (24296) 从系统启动开始累计到当前时刻，处于用户态的运行时间，不包含 nice值为负进程。 Time spent in user mode
nice (3660) 从系统启动开始累计到当前时刻，nice值为负的进程所占用的CPU时间 Time spent in user mode with low priority(nice)
system (18105) 从系统启动开始累计到当前时刻，处于核心态的运行时间 Time spent in system mode
idle (899033) 从系统启动开始累计到当前时刻，除IO等待时间以外的其它等待时间 Time spent in the idle task. This value should be USER_HZ times the second entry in the /proc/uptime pseudo-file
iowait (640) 从系统启动开始累计到当前时刻，IO等待时间(since 2.5.41) Time waiting for I/O to complete
irq (3576) 从系统启动开始累计到当前时刻，硬中断时间(since 2.6.0-test4) Time servicing interrupts
softirq (2202) 从系统启动开始累计到当前时刻，软中断时间(since 2.6.0-test4) Time servicing softirqs.

那么总的 cpu 时间 totalCpuTime = user + nice + system + idle + iowait + irq + softirq

使用率计算

取一段时间内的 两份数据 totalCpuTime 和 idle time

  1. totalCpuTimeA ，idleA
  2. totalCpuTimeB ，idleB

计算这一段时间内的 cpu 使用率：

cpu 使用率 = ((totalCpuTimeB - totalCpuTimeA) - (idleB - idleA) ) / (totalCpuTimeB - totalCpuTimeA) * 100

单个进程 cpu 使用率计算

数据来源 ： /proc/pid_of_process/stat

以华为手机 system_server 进程为例

$ adb shell cat /proc/1286/stat
1286 (system_server) S 889 889 0 0 -1 1077952832 404759 0 2760 0 9595 4059 0 0 18 -2 265 0 599 10783543296 86828 18446744073709551615 1 1 0 0 0 0 4612 0 1073794299 0 0 0 17 1 0 0 76 0 0 0 0 0 0 0 0 0 0

数据分析

说明：以下只解释对我们计算Cpu使用率有用相关参数

参数 解释 原文
pid=1286 进程号 The process ID.
comm=system_server 进程名信息 The filename of the executable, in parentheses. This is visible whether or not the executable is swapped out
utime=9595 该任务在用户态运行的时间，单位为jiffies Amount of time that this process has been scheduled in user mode, measured in clock ticks (divide by sysconf(_SC_CLK_TCK)). This includes guest time, guest_time (time spent running a virtual CPU, see below), so that applications that are not aware of the guest time field do not lose that time from their calculations.
stime=4059 该任务在核心态运行的时间，单位为jiffies Amount of time that this process has been scheduled in kernel mode, measured in clock ticks (divide by sysconf(_SC_CLK_TCK)).
cutime=0 用户态等待子进程的消耗，单位为jiffies Amount of time that this process's waited-for chil‐ dren have been scheduled in user mode, measured in clock ticks (divide by sysconf(_SC_CLK_TCK)). (See also times(2).) This includes guest time, cguest_time (time spent running a virtual CPU, see below)
cstime=0 内核态等待子进程的消耗，单位为jiffies Amount of time that this process's waited-for chil‐ dren have been scheduled in kernel mode, measured in clock ticks (divide by sysconf(_SC_CLK_TCK))

那么总的进程 cpu 时间 totalProcessCpuTime = utime + stime + cutime + cstime

使用率计算

取一段时间内的两份数据

  1. totalCpuTimeA ，totalProcessCpuTimeA
  2. totalCpuTimeB ，totalProcessCpuTimeB

cpu 使用率 = (totalProcessCpuTimeB - ，totalProcessCpuTimeA ) / (totalCpuTimeB - totalCpuTimeA) * 100 * CPU_CORE_COUNT

其中 CPU_CORE_COUNT 是手机的核数

示例

以一段复杂的操作为例，下面可以计算出这一段时间内的整机 cpu 使用率和 SystemServer(或者其他你比较关系的进程) 的 cpu 使用率

python cpu_usage_calculation.py -p system_server -f 2 -t 20

-p : 指定包名 -f : 指定抓取频率(单位为 s) -t : 指定抓取时长(单位为 s)

通过使用率的对比就可以分析这一段时间内的负载，可以作为竞品对比或者优化验证

All devices cpuinfo (整机 cpu 使用率)
0s to 5s  cpu usage :98.0
5s to 10s  cpu usage :80.0
10s to 15s  cpu usage :57.0
15s to 20s  cpu usage :21.0

SystemServer cpuinfo (SystemServer  cpu 使用率)
0s to 5s  cpu usage :48.0
5s to 10s  cpu usage :35.0
10s to 15s  cpu usage :24.0
15s to 20s  cpu usage :2.0