c - 在Linux(RedHat)中，C函数malloc_stats()与/proc//stat常驻内存大小相比显示不同的值

Question

例如
对于在Redhat Linux中运行的进程
按照/proc/{pid}/stat的常驻页面*页面大小=> 30 GB

按照malloc_stats() => 2.5 GB

知道为什么会这样吗？

Arena 0:
system bytes     =  465162240
in use bytes     =  465037200
Arena 1:
system bytes     =    1003520
in use bytes     =     980656
Arena 2:
system bytes     =    8065024
in use bytes     =    7771728
Arena 3:
system bytes     = 2278395904
in use bytes     = 2276584320
Arena 4:
system bytes     =    1482752
in use bytes     =    1236112
Arena 5:
system bytes     =    1482752
in use bytes     =    1235440
Arena 6:
system bytes     =    1482752
in use bytes     =    1240512
Total (incl. mmap):
system bytes     = 2782,699,520
in use bytes     = 2779710544
max mmap regions =          9
max mmap bytes   =   25624576

Answer 1

malloc_stats与用户区域中malloc的实现相关。
pmap或/proc/self/stat与虚拟地址空间及其在内核 Realm 的感知有关，它不仅随mmap调用的malloc发生变化，而且随mmap的其他调用(包括与动态链接程序(ld.so)相关的调用)发生变化。

阅读一个好的textbook on operating systems。另请参见https://linuxatemyram.com/和proc(5)，mmap(2)，execve(2)，malloc(3)