https://pypi.org/project/gprof2dot/
http://sam.zoy.org/writings/programming/gprof-helper.c
http://sam.zoy.org/writings/programming/gprof.html
http://www.graphviz.org/download/
https://www.cnblogs.com/rocketfan/archive/2009/11/15/1603465.html
https://www.cnblogs.com/andashu/p/6378000.html
http://blog.51cto.com/xiamachao/1857696
https://blog.csdn.net/weiwangchao_/article/details/51282697
https://www.xuebuyuan.com/1890848.html
g++ -pg -o test.exe test.cpp
./test
gcc -g -pg test.c -o test
gprof ./test > report.txt
gprof2dot report.txt > test.dot
dot -Tpng -o test.png
gprof -b ./RoomSvr | gprof2dot | dot -Tpng -o output.png