Linux下评估程序运行时间及内存占用情况的简便方法

Linux下评估程序运行时间及内存占用情况的简便方法

Sason@CSDN

从一篇英文论文中看到用于简易评估程序运行时间及内存占用情况的方法，查找资料后记录如下。

本文末尾附输出内存使用情况的函数。

1.评估程序运行时间：

Linux下进行C程序开发时，可使用getrusage()函数进行程序运行时间的简易评估。

使用usage.ru_utime进行用户CPU时间（user CPU time）评估，对于系统CPU时间（system CPU time）评估使用usage.ru_stime.

如果程序运行于内核模式（kernel mode），使用ru_stime, 否则使用ru_utime.

getrusage()函数的说明：http://man7.org/linux/man-pages/man2/getrusage.2.html

StackOverFlow的讨论：http://stackoverflow.com/questions/10509660/getting-getrusage-to-measure-system-time-in-c

代码示例：

#include <sys/time.h>

#include <sys/resource.h>

#include <unistd.h>

#include <stdio.h>

int main() {

struct rusage usage;

struct timeval start, end;

int i, j, k = 0;

getrusage(RUSAGE_SELF, &usage);

start = usage.ru_utime; //usage.ru_stime

for (i = 0; i < 10000; i++) {

/* Double loop for more interesting results. */

for (j = 0; j < 10000; j++) {

k += 20;

}

}

getrusage(RUSAGE_SELF, &usage);

end = usage.ru_utime; //usage.ru_stime

printf("Started at: %ld.%lds\n", start.tv_sec, start.tv_usec);

printf("Ended at: %ld.%lds\n", end.tv_sec, end.tv_usec);

return 0;

}

2. 评估内存占用情况：

察看/proc/[PID]/statm,
其中[PID]是进程的PID号.

推荐阅读：http://elinux.org/Runtime_Memory_Measurement

来自http://www.lindevdoc.org/wiki//proc/pid/statm的解释：

The /proc/pid/statm file describes the memory usage of a process with the specified PID.

It is a single-line text file with following entries separated by whitespace:

Total process size (like VmSize in /proc/pid/status)

Resident set size (like VmRSS in /proc/pid/status)

Number of shared pages

Number of code pages, not including shared libraries[1]

Currently unused and always 0 (used to be number of library pages before kernel 2.6)

Number of data and stack pages together[2]

Currently unused and always 0 (used to be number of dirty pages before kernel 2.6)

这些输出参数的解释：

Size (total pages) 任务虚拟地址空间的大小 VmSize/4

Resident(pages) 应用程序正在使用的物理内存的大小 VmRSS/4

Shared(pages) 共享页数 0

Trs(pages) 程序所拥有的可执行虚拟内存的大小 VmExe/4

Lrs(pages) 被映像到任务的虚拟内存空间的库的大小 VmLib/4

Drs(pages) 程序数据段和用户态的栈的大小 （VmData+ VmStk ）4

dt(pages) 脏页数量

增加上个例子中的循环次数，运行后，察看内存占用情况：

admin@admin:~$ cat /proc/3292/statm

501 70 57 1 0 41 0

admin@admin:~$ cat /proc/3292/status

Name: measuretime

State: R (running)

Tgid: 3292

Pid: 3292

PPid: 2693

TracerPid: 0

Uid: 1000 1000 1000 1000

Gid: 1000 1000 1000 1000

FDSize: 256

Groups: 4 24 27 30 46 109 124 1000

VmPeak: 2108 kB

VmSize: 2004 kB //等于total pages * 4 = 501 * 4 = 2004

VmLck: 0 kB

VmPin: 0 kB

VmHWM: 280 kB

VmRSS: 280 kB //等于resident pages * 4 = 70 * 4 = 280

VmData: 28 kB //VmData + VmStk = 164 164 / 4 = 41 (Drs pages)

VmStk: 136 kB

VmExe: 4 kB

VmLib: 1804 kB

VmPTE: 12 kB

VmSwap: 0 kB

Threads: 1

SigQ: 0/15994

SigPnd: 0000000000000000

ShdPnd: 0000000000000000

SigBlk: 0000000000000000

SigIgn: 0000000000000000

SigCgt: 0000000000000000

CapInh: 0000000000000000

CapPrm: 0000000000000000

CapEff: 0000000000000000

CapBnd: ffffffffffffffff

Cpus_allowed: f

Cpus_allowed_list: 0-3

Mems_allowed: 1

Mems_allowed_list: 0

voluntary_ctxt_switches: 1

nonvoluntary_ctxt_switches: 41173

打印内存使用情况的函数：

void printMemoryUsage() {

char buf[30];

snprintf(buf, 30, "/proc/%u/statm", (unsigned)getpid());

FILE* pf = fopen(buf, "r");

if (pf) {

unsigned size; // total program size

//unsigned resident;// resident set size

//unsigned share;// shared pages

//unsigned text;// text (code)

//unsigned lib;// library

//unsigned data;// data/stack

//unsigned dt;// dirty pages (unused in Linux 2.6)

if ( fscanf(pf, "%u" /* %u %u %u %u %u"*/, &size/*, &resident, &share, &text, &lib, &data*/) > 0);

cout << (size / 1024.0) << " MB mem used\n";

//DOMSGCAT(MSTATS, std::setprecision(4) << size / (1024.0) << "MB mem used");

}

fclose(pf);

}

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