第一句子网 > C++ performance 性能分析工具(sanitizers valgrind gprof gperftools perf）的使用

C++ performance 性能分析工具(sanitizers valgrind gprof gperftools perf）的使用

时间：2023-02-11 03:28:21

文章目录

1. time2. Sanitizers2.1 内存泄漏`-fsanitize=leak`2.2 地址错误 `-fsanitize=address`3. Valgrind 工具集3.1 memory error detector3.1.1 简单例子3.1.2 更多3.2 call-graph generating4. GNU gprof (GNU Profiler)4.1 以文本显示4.2 以图形显示5. gperftools (Google Performance Tools)5.1 text 报告5.2 pdf 报告6. perf6.1 文本报告6.2 火焰图6.3 perf diff

参考：

How can I profile C++ code running on Linux?

CPU Profiling Tools on Linux

1. time

Linuxtime命令的用途，在于量测特定指令执行时所需消耗的时间及系统资源等资讯。

语法：

time [options] COMMAND [arguments]

参数：

-o或 --output=FILE：设定结果输出档。这个选项会将 time 的输出写入所指定的档案中。如果档案已经存在，系统将覆写其内容。

-a或 --append：配合 -o 使用，会将结果写到档案的末端，而不会覆盖掉原来的内容。

-fFORMAT 或 --format=FORMAT：以 FORMAT 字串设定显示方式。当这个选项没有被设定的时候，会用系统预设的格式。不过你可以用环境变数 time 来设定这个格式，如此一来就不必每次登入系统都要设定一次。

示例：

➜ antlr4.9.2-develop git:(master) ✗ time dateWed Jan 19 14:37:41 CST date 0.00s user 0.00s system 32% cpu 0.003 total

更多：/linux/time.html

2. Sanitizers

GitHub：/google/Sanitizers

使用文档：/google/sanitizers/wiki

简介：

Sanitizers是谷歌发起的开源工具集，包括了AddressSanitizer,MemorySanitizer,ThreadSanitizer,LeakSanitizer，Sanitizers项目本是LLVM项目的一部分，但GNU也将该系列工具加入到了自家的 GCC 编译器中。GCC从4.8版本开始支持 Address 和 Thread Sanitizer，4.9 版本开始支持 Leak Sanitizer 和 UB Sanitizer，这些都是查找隐藏 Bug 的利器。

特点：

Sanitizer可以在检测到内存泄露第一时间立刻终止进程，并且它可以深入检测（随应用进程一起编译）。

相关标志：

地址错误：-fsanitize=address内存错误：-fsanitize=memory内存泄漏：-fsanitize=leak线程竞速问题：-fsanitize=thread未定义问题：-fsanitize=undefined

为方便回溯可同时添加保留函数指针标志：-fno-omit-frame-pointer

gcc/g++ 使用 sanitizer：

gcc/g++编译只需要将 sanitizer 的标志作为 flag 设置即可，如下：

gcc/g++ -fsanitize=address -g -fno-omit-frame-pointer test.cpp

CMakeLists 使用 sanitizer ：

使用CMAKE_CXX_FLAGS或add_compile_options的配置即可使用，如下：

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=address -fno-omit-frame-pointer")

或

add_compile_options(-fsanitize=address -fno-omit-frame-pointer)link_libraries(-fsanitize=address)

2.1 内存泄漏`-fsanitize=leak`

使用示例：

建立以下名为memory_leak.cpp的文件，其中发生了内存泄漏：

#include <iostream>#include <string>int main(int argc, char* argv[]) {std::string* s1 = new std::string("hello world!");std::cout << *s1 << std::endl;return 0;}

编写CMakeLists：

cmake_minimum_required(VERSION 3.10)project (demo)SET(CMAKE_BUILD_TYPE "Debug")SET(CMAKE_CXX_FLAGS_DEBUG "$ENV{CXXFLAGS} -O0 -Wall -g -Wno-attributes")set(CMAKE_CXX_STANDARD 11)set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=leak -fno-omit-frame-pointer")add_executable(memory_leak memory_leak.cpp)

运行：

➜ build cmake .. && make -j8-- Configuring done-- Generating done-- Build files have been written to: /data/tangxing/verify/sanitizers/build[ 50%] Building CXX object CMakeFiles/memory_leak.dir/memory_leak.cpp.o[100%] Linking CXX executable memory_leak[100%] Built target memory_leak➜ build ./memory_leak hello world!===================================================================18801==ERROR: LeakSanitizer: detected memory leaksDirect leak of 32 byte(s) in 1 object(s) allocated from:#0 0x7f672f8e3043 in operator new(unsigned long) ../../.././libsanitizer/lsan/:222#1 0x400c0d in main /data/tangxing/verify/sanitizers/memory_leak.cpp:5#2 0x7f672ec33554 in __libc_start_main (/lib64/libc.so.6+0x22554)SUMMARY: LeakSanitizer: 32 byte(s) leaked in 1 allocation(s).

通过结果，我们看出，在main.cpp第5行检测到了内存泄漏：

2.2 地址错误`-fsanitize=address`

示例代码：

#include <iostream>#include <string>int main(int argc, char* argv[]) {int a[2] = {1, 0};int b = a[2];return 0;}

CMakeLists.txt ：

cmake_minimum_required(VERSION 3.10)project (demo)SET(CMAKE_BUILD_TYPE "Debug")SET(CMAKE_CXX_FLAGS_DEBUG "$ENV{CXXFLAGS} -O0 -Wall -g -Wno-attributes")set(CMAKE_CXX_STANDARD 11)set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=address -fno-omit-frame-pointer")add_executable(memory_leak memory_leak.cpp)

运行结果：

===================================================================31176==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffe3971eec8 at pc 0x000000400c15 bp 0x7ffe3971ee70 sp 0x7ffe3971ee68READ of size 4 at 0x7ffe3971eec8 thread T0#0 0x400c14 in main /data/tangxing/verify/sanitizers/memory_leak.cpp:6#1 0x7f01100ee554 in __libc_start_main (/lib64/libc.so.6+0x22554)#2 0x400a68 (/data/tangxing/verify/sanitizers/build/memory_leak+0x400a68)Address 0x7ffe3971eec8 is located in stack of thread T0 at offset 40 in frame#0 0x400b21 in main /data/tangxing/verify/sanitizers/memory_leak.cpp:4This frame has 1 object(s):[32, 40) 'a' (line 5) <== Memory access at offset 40 overflows this variableHINT: this may be a false positive if your program uses some custom stack unwind mechanism, swapcontext or vfork(longjmp and C++ exceptions *are* supported)SUMMARY: AddressSanitizer: stack-buffer-overflow /data/tangxing/verify/sanitizers/memory_leak.cpp:6 in mainShadow bytes around the buggy address:0x1000472dbd80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 000x1000472dbd90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 000x1000472dbda0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 000x1000472dbdb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 000x1000472dbdc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00=>0x1000472dbdd0: 00 00 00 00 f1 f1 f1 f1 00[f3]f3 f3 00 00 00 000x1000472dbde0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 000x1000472dbdf0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 000x1000472dbe00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 000x1000472dbe10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 000x1000472dbe20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00Shadow byte legend (one shadow byte represents 8 application bytes):Addressable: 00Partially addressable: 01 02 03 04 05 06 07 Heap left redzone: faFreed heap region: fdStack left redzone:f1Stack mid redzone: f2Stack right redzone:f3Stack after return:f5Stack use after scope: f8Global redzone:f9Global init order: f6Poisoned by user: f7Container overflow:fcArray cookie: acIntra object redzone: bbASan internal: feLeft alloca redzone:caRight alloca redzone: cbShadow gap: cc==31176==ABORTING

我们看到在第5行发生了地址错误。

3. Valgrind 工具集

官网：/

用户手册：/docs/manual/manual.html

图形化：/jrfonseca/gprof2dot

参考：/yanghao23/article/details/7514587

简介：Valgrind是一个用于构建动态分析工具的工具框架。有一些 Valgrind 工具可以自动检测许多内存管理和线程错误，并详细分析你的程序。您还可以使用 Valgrind 来构建新的工具。Valgrind 发行版目前包括7个production-quality的工具:

a memory error detector,

two thread error detectors,

a cache and branch-prediction profiler,

a call-graph generating cache and branch-prediction profiler,

and two different heap profilers.

It also includes an experimental SimPoint basic block vector generator.

3.1 memory error detector

最常用的工具，用来检测程序中出现的内存问题，所有对内存的读写都会被检测到，一切对malloc、free、new、delete的调用都会被捕获。所以，它能检测以下问题：

1、对未初始化内存的使用；

2、读/写释放后的内存块；

3、读/写超出 malloc 分配的内存块；

4、读/写不适当的栈中内存块；

5、内存泄漏，指向一块内存的指针永远丢失；

6、不正确的malloc/free或new/delete匹配；

7、memcpy() 相关函数中的 dst 和 src 指针重叠。

这些问题往往是 C/C++ 程序员最头疼的问题，Memcheck 能在这里帮上大忙。

3.1.1 简单例子

示例代码：

#include <iostream>#include <string>int main(int argc, char* argv[]) {std::string* s1 = new std::string("hello world!");std::cout << *s1 << std::endl;int a[2] = {1, 0};int b = a[2];return 0;}

CMakeLists.txt ：

cmake_minimum_required(VERSION 3.10)project (demo)set(CMAKE_CXX_STANDARD 11)SET(CMAKE_BUILD_TYPE "Debug")SET(CMAKE_CXX_FLAGS_DEBUG "$ENV{CXXFLAGS} -O0 -Wall -g -Wno-attributes")SET(CMAKE_CXX_FLAGS_RELEASE "$ENV{CXXFLAGS} -O3 -Wall -Wno-attributes")add_executable(memcheck memcheck.cpp)

使用：

valgrind --leak-check=full ./可执行文件名

控制台输出：

==8398== Memcheck, a memory error detector==8398== Copyright (C) 2002-, and GNU GPL'd, by Julian Seward et al.==8398== Using Valgrind-3.15.0 and LibVEX; rerun with -h for copyright info==8398== Command: ./memcheck==8398== hello world!==8398== ==8398== HEAP SUMMARY:==8398==in use at exit: 32 bytes in 1 blocks==8398== total heap usage: 2 allocs, 1 frees, 72,736 bytes allocated==8398== ==8398== 32 bytes in 1 blocks are definitely lost in loss record 1 of 1==8398== at 0x4C2A593: operator new(unsigned long) (vg_replace_malloc.c:344)==8398== by 0x400ADD: main (memcheck.cpp:5)==8398== ==8398== LEAK SUMMARY:==8398== definitely lost: 32 bytes in 1 blocks==8398== indirectly lost: 0 bytes in 0 blocks==8398==possibly lost: 0 bytes in 0 blocks==8398== still reachable: 0 bytes in 0 blocks==8398== suppressed: 0 bytes in 0 blocks==8398== ==8398== For lists of detected and suppressed errors, rerun with: -s==8398== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)

我们可以看出在memcheck.cpp第5行发生了内存泄漏。

3.1.2 更多

例子：

#include <stdlib.h>#include <malloc.h>#include <string.h>void test() {int *ptr = (int*)malloc(sizeof(int)*10);ptr[10] = 7; // 内存越界memcpy(ptr +1, ptr, 5); // 踩内存free(ptr); free(ptr);// 重复释放int *p1;*p1 = 1; // 非法指针}int main(void) {test();return 0;}

CMakeLists.txt

编译后使用：

valgrind --leak-check=full ./可执行文件名

检测结果：

[100%] Built target memcheck==1203== Memcheck, a memory error detector==1203== Copyright (C) 2002-, and GNU GPL'd, by Julian Seward et al.==1203== Using Valgrind-3.15.0 and LibVEX; rerun with -h for copyright info==1203== Command: ./memcheck==1203== ==1203== Invalid write of size 4 # 内存越界==1203== at 0x400600: test() (memcheck.cpp:8)==1203== by 0x40064F: main (memcheck.cpp:20)==1203== Address 0x5b0aca8 is 0 bytes after a block of size 40 alloc'd==1203== at 0x4C29F73: malloc (vg_replace_malloc.c:309)==1203== by 0x4005F3: test() (memcheck.cpp:6)==1203== by 0x40064F: main (memcheck.cpp:20)==1203== ==1203== Source and destination overlap in memcpy(0x5b0ac84, 0x5b0ac80, 5) # 踩内存==1203== at 0x4C2E81D: memcpy@@GLIBC_2.14 (vg_replace_strmem.c:1035)==1203== by 0x400621: test() (memcheck.cpp:10)==1203== by 0x40064F: main (memcheck.cpp:20)==1203== ==1203== Invalid free() / delete / delete[] / realloc() # 重复释放==1203== at 0x4C2B06D: free (vg_replace_malloc.c:540)==1203== by 0x400639: test() (memcheck.cpp:13)==1203== by 0x40064F: main (memcheck.cpp:20)==1203== Address 0x5b0ac80 is 0 bytes inside a block of size 40 free'd==1203== at 0x4C2B06D: free (vg_replace_malloc.c:540)==1203== by 0x40062D: test() (memcheck.cpp:12)==1203== by 0x40064F: main (memcheck.cpp:20)==1203== Block was alloc'd at==1203== at 0x4C29F73: malloc (vg_replace_malloc.c:309)==1203== by 0x4005F3: test() (memcheck.cpp:6)==1203== by 0x40064F: main (memcheck.cpp:20)==1203== ==1203== Use of uninitialised value of size 8 # 非法指针==1203== at 0x40063E: test() (memcheck.cpp:16)==1203== by 0x40064F: main (memcheck.cpp:20)==1203== ==1203== ==1203== Process terminating with default action of signal 11 (SIGSEGV) # 由于非法指针赋值导致的程序崩溃==1203== Bad permissions for mapped region at address 0x400660==1203== at 0x40063E: test() (memcheck.cpp:16)==1203== by 0x40064F: main (memcheck.cpp:20)==1203== ==1203== HEAP SUMMARY:==1203==in use at exit: 0 bytes in 0 blocks==1203== total heap usage: 2 allocs, 3 frees, 72,744 bytes allocated==1203== ==1203== All heap blocks were freed -- no leaks are possible==1203== ==1203== Use --track-origins=yes to see where uninitialised values come from==1203== For lists of detected and suppressed errors, rerun with: -s==1203== ERROR SUMMARY: 4 errors from 4 contexts (suppressed: 0 from 0)[1] 1203 segmentation fault valgrind --leak-check=full ./memcheck

valgrind把我们的几个内存错误全都检测了出来。

3.2 call-graph generating

和gprof类似的分析工具，但它对程序的运行观察更是入微，能给我们提供更多的信息。和gprof不同，它不需要在编译源代码时附加特殊选项，但加上调试选项是推荐的。Callgrind 收集程序运行时的一些数据，建立函数调用关系图，还可以有选择地进行 cache 模拟。在运行结束时，它会把分析数据写入一个文件。callgrind_annotate可以把这个文件的内容转化成可读的形式。

生成可视化的图形需要下载gprof2dot：/jrfonseca/gprof2dot/blob/master/gprof2dot.py

这是个 python 脚本，把它下载之后修改其权限chmod +7 gprof2dot.py，并把这个脚本添加到$PATH路径中的任一文件夹下，我是将它放到了/usr/bin目录下，这样就可以直接在终端下执行gprof2dot.py了。

**示例代码：call.cpp**

#include <stdio.h>#include <malloc.h>#include <chrono>#include <thread>void test(){std::this_thread::sleep_for(std::chrono::milliseconds(1000));}void f(){int i;for( i = 0; i < 5; i ++)test();}int main(){f();printf("process is over!\n");return 0;}

CMakeLists.txt ：

使用callgrind：

valgrind --tool=callgrind ./可执行程序

执行完成后在目录下生成"callgrind.out.<pid>"的文件这是分析文件，可以直接利用下面的命令打印结果：

callgrind_annotate callgrind.out.<pid>

也可以使用下面的命令来生成图形化结果:

gprof2dot.py -f callgrind callgrind.out.<pid> |dot -Tpng -o report.png

4. GNU gprof (GNU Profiler)

参考gprof用户数手册：/binutils/docs-2.17/gprof/index.html

gprof是gcc自带的性能测试工具，可以统计出各个函数的调用次数、时间、以及函数调用图。

使用步骤：

（1）编译时候打开编译开关，-pg

（2）运行程序（程序一定要正常运行完毕才会生成性能报告）

（3）运行性能测试工具来生成报告。

我们还是使用第上一小节的代码：call.cpp

CMakeLists.txt :

cmake_minimum_required(VERSION 3.10)project (demo)set(CMAKE_CXX_STANDARD 11)SET(CMAKE_BUILD_TYPE "Debug")SET(CMAKE_CXX_FLAGS_DEBUG "$ENV{CXXFLAGS} -O0 -Wall -g -pg -Wno-attributes")SET(CMAKE_CXX_FLAGS_RELEASE "$ENV{CXXFLAGS} -O3 -Wall -Wno-attributes")add_executable(call call.cpp)

编译运行程序后，生成了gmon.out文件。

4.1 以文本显示

执行以下命令：

gprof <options> <可执行文件> gmon.out

生成了以下内容，我们发现不好查看：

% cumulative self selftotal time seconds seconds calls Ts/call Ts/call name 0.000.000.00 350.000.00 std::chrono::duration<long, std::ratio<1l, 1000l> >::count() const0.000.000.00 150.000.00 std::chrono::duration<long, std::ratio<1l, 1000l> >::duration<long, void>(long const&)0.000.000.00 100.000.00 std::chrono::duration<long, std::ratio<1l, 1l> >::count() const0.000.000.00 50.000.00 test()0.000.000.00 50.000.00 std::chrono::duration<long, std::ratio<1l, 1000000000l> >::count() const0.000.000.00 50.000.00 void std::this_thread::sleep_for<long, std::ratio<1l, 1000l> >(std::chrono::duration<long, std::ratio<1l, 1000l> > const&)0.000.000.00 50.000.00 std::enable_if<std::chrono::__is_duration<std::chrono::duration<long, std::ratio<1l, 1000000000l> > >::value, std::chrono::duration<long, std::ratio<1l, 1000000000l> > >::type std::chrono::duration_cast<std::chrono::duration<long, std::ratio<1l, 1000000000l> >, long, std::ratio<1l, 1000l> >(std::chrono::duration<long, std::ratio<1l, 1000l> > const&)0.000.000.00 50.000.00 std::enable_if<std::chrono::__is_duration<std::chrono::duration<long, std::ratio<1l, 1000l> > >::value, std::chrono::duration<long, std::ratio<1l, 1000l> > >::type std::chrono::duration_cast<std::chrono::duration<long, std::ratio<1l, 1000l> >, long, std::ratio<1l, 1l> >(std::chrono::duration<long, std::ratio<1l, 1l> > const&)0.000.000.00 50.000.00 std::enable_if<std::chrono::__is_duration<std::chrono::duration<long, std::ratio<1l, 1l> > >::value, std::chrono::duration<long, std::ratio<1l, 1l> > >::type std::chrono::duration_cast<std::chrono::duration<long, std::ratio<1l, 1l> >, long, std::ratio<1l, 1000l> >(std::chrono::duration<long, std::ratio<1l, 1000l> > const&)0.000.000.00 50.000.00 std::chrono::duration_values<long>::zero()0.000.000.00 50.000.00 std::chrono::duration<long, std::ratio<1l, 1000000000l> > std::chrono::__duration_cast_impl<std::chrono::duration<long, std::ratio<1l, 1000000000l> >, std::ratio<1000000l, 1l>, long, false, true>::__cast<long, std::ratio<1l, 1000l> >(std::chrono::duration<long, std::ratio<1l, 1000l> > const&)0.000.000.00 50.000.00 std::chrono::duration<long, std::ratio<1l, 1000l> > std::chrono::__duration_cast_impl<std::chrono::duration<long, std::ratio<1l, 1000l> >, std::ratio<1000l, 1l>, long, false, true>::__cast<long, std::ratio<1l, 1l> >(std::chrono::duration<long, std::ratio<1l, 1l> > const&)0.000.000.00 50.000.00 std::chrono::duration<long, std::ratio<1l, 1l> > std::chrono::__duration_cast_impl<std::chrono::duration<long, std::ratio<1l, 1l> >, std::ratio<1l, 1000l>, long, true, false>::__cast<long, std::ratio<1l, 1000l> >(std::chrono::duration<long, std::ratio<1l, 1000l> > const&)0.000.000.00 50.000.00 std::chrono::duration<long, std::ratio<1l, 1000000000l> >::duration<long, void>(long const&)0.000.000.00 50.000.00 std::chrono::duration<long, std::ratio<1l, 1000l> >::zero()0.000.000.00 50.000.00 std::chrono::duration<long, std::ratio<1l, 1000l> >::duration<int, void>(int const&)0.000.000.00 50.000.00 std::chrono::duration<long, std::ratio<1l, 1000l> >::duration<long, std::ratio<1l, 1l>, void>(std::chrono::duration<long, std::ratio<1l, 1l> > const&)0.000.000.00 50.000.00 std::chrono::duration<long, std::ratio<1l, 1l> >::duration<long, void>(long const&)0.000.000.00 50.000.00 bool std::chrono::operator<=<long, std::ratio<1l, 1000l>, long, std::ratio<1l, 1000l> >(std::chrono::duration<long, std::ratio<1l, 1000l> > const&, std::chrono::duration<long, std::ratio<1l, 1000l> > const&)0.000.000.00 50.000.00 bool std::chrono::operator< <long, std::ratio<1l, 1000l>, long, std::ratio<1l, 1000l> >(std::chrono::duration<long, std::ratio<1l, 1000l> > const&, std::chrono::duration<long, std::ratio<1l, 1000l> > const&)0.000.000.00 50.000.00 std::common_type<std::chrono::duration<long, std::ratio<1l, 1000l> >, std::chrono::duration<long, std::ratio<1l, 1l> > >::type std::chrono::operator-<long, std::ratio<1l, 1000l>, long, std::ratio<1l, 1l> >(std::chrono::duration<long, std::ratio<1l, 1000l> > const&, std::chrono::duration<long, std::ratio<1l, 1l> > const&)0.000.000.00 10.000.00 f()

4.2 以图形显示

执行以下命令：

gprof ./可执行文件 | gprof2dot.py |dot -Tpng -o report.png

生成可视化的图形需要下载gprof2dot：/jrfonseca/gprof2dot/blob/master/gprof2dot.py

这里就生成了调用图：

5. gperftools (Google Performance Tools)

GitHub: /gperftools/gperftools

参考：/NIGHTFIGHTING/gperftools-tutorial

编译安装：

# 从github下载gperftools源码并解压wget /gperftools/gperftools/releases/download/gperftools-2.9.1/gperftools-2.9.1.tar.gztar -xvf gperftools-2.9.1.tar.gzcd gperftools-2.9.1# 编译./configuremake -j8# 安装到系统文件夹sudo make install

call.cpp ：

#include <stdio.h>#include <malloc.h>#include <chrono>#include <thread>void test(){std::this_thread::sleep_for(std::chrono::milliseconds(1));}void f(){int i;for( i = 0; i < 100; i ++){test();}}int main(){for(int i=0; i<100; i++) {f();}printf("process is over!\n");return 0;}

CMakeLists.txt :

cmake_minimum_required(VERSION 3.10)project (demo)set(CMAKE_CXX_STANDARD 11)SET(CMAKE_BUILD_TYPE "Debug")# SET(CMAKE_BUILD_TYPE "Release")SET(CMAKE_CXX_FLAGS_DEBUG "$ENV{CXXFLAGS} -O0 -Wall -g -lprofiler -Wno-attributes")SET(CMAKE_CXX_FLAGS_RELEASE "$ENV{CXXFLAGS} -O3 -Wall -Wno-attributes")add_executable(call call.cpp)

生成报告：

CPUPROFILE=./prof.out ./call

5.1 text 报告

命令：

➜ build pprof ./call test_capture.prof --text Using local file ./call.Using local file test_capture.prof.Total: 3 samples2 66.7% 66.7% 2 66.7% __nanosleep_nocancel1 33.3% 100.0% 1 33.3% std::chrono::operator< 0 0.0% 100.0% 3 100.0% __libc_start_main0 0.0% 100.0% 3 100.0% _start0 0.0% 100.0% 3 100.0% f0 0.0% 100.0% 3 100.0% main0 0.0% 100.0% 1 33.3% std::chrono::operator<=0 0.0% 100.0% 3 100.0% std::this_thread::sleep_for0 0.0% 100.0% 3 100.0% test

5.2 pdf 报告

命令：

pprof ./call test_capture.prof --pdf > prof.pdf

6. perf

Wiki：https://perf./index.php/Main_Page

Perf是内置于Linux 内核源码树中的性能剖析(profiling)工具。其基于事件采样原理，以性能事件为基础，常用于性能瓶颈的查找与热点代码的定位。

性能调优工具如perf，Oprofile 等的基本原理都是对被监测对象进行采样，最简单的情形是根据 tick 中断进行采样，即在 tick 中断内触发采样点，在采样点里判断程序当时的上下文。假如一个程序 90% 的时间都花费在函数 foo() 上，那么 90% 的采样点都应该落在函数 foo的上下文中。只要采样频率足够高，采样时间足够长，那么以上推论就比较可靠。因此，通过 tick 触发采样，我们便可以了解程序中哪些地方最耗时间，从而重点分析。

call.cpp:

CMakeLists.txt :

cmake_minimum_required(VERSION 3.10)project (demo)set(CMAKE_CXX_STANDARD 11)SET(CMAKE_BUILD_TYPE "Debug")# SET(CMAKE_BUILD_TYPE "Release")SET(CMAKE_CXX_FLAGS_DEBUG "$ENV{CXXFLAGS} -O0 -Wall -g -Wno-attributes")SET(CMAKE_CXX_FLAGS_RELEASE "$ENV{CXXFLAGS} -O3 -Wall -Wno-attributes")add_executable(call call.cpp)

6.1 文本报告

命令：

perf record -e cpu-clock -g ./可执行文件

示例：

➜ build perf record -e cpu-clock -g ./call WARNING: Kernel address maps (/proc/{kallsyms,modules}) are restricted,check /proc/sys/kernel/kptr_restrict.Samples in kernel functions may not be resolved if a suitable vmlinuxfile is not found in the buildid cache or in the vmlinux path.Samples in kernel modules won't be resolved at all.If some relocation was applied (e.g. kexec) symbols may be misresolvedeven with a suitable vmlinux or kallsyms file.process is over![ perf record: Woken up 1 times to write data ][ perf record: Captured and wrote 0.004 MB perf.data (26 samples) ]➜ build

结果：

6.2 火焰图

上面通过文件查看不够直观，还有一种火焰图分析的方式：

工具下载：git clone /brendangregg/FlameGraph.git

➜ build cd ..# 工具下载➜ perf git clone /brendangregg/FlameGraph.gitCloning into 'FlameGraph'...remote: Enumerating objects: 1147, done.remote: Counting objects: 100% (28/28), done.remote: Compressing objects: 100% (23/23), done.remote: Total 1147 (delta 13), reused 13 (delta 5), pack-reused 1119Receiving objects: 100% (1147/1147), 1.90 MiB | 0 bytes/s, done.Resolving deltas: 100% (659/659), done.➜ perf cd build # 使用perf script工具对perf.data进行解析➜ build perf script -i perf.data &> perf.unfold# 将perf.unfold中的符号进行折叠➜ build ../FlameGraph/stackcollapse-perf.pl perf.unfold &> perf.folded# 最后生成svg图➜ build ../FlameGraph/flamegraph.pl perf.folded > perf.svg

perf.svg：