pss在/proc/pid/smaps中是什么意思

问题描述

我对/proc/pid/smaps中的pss列感到困惑，所以我编写了一个程序对其进行测试:

I was confused about the pss column in /proc/pid/smaps, so I wrote a program to test it:

void sa();
int main(int argc,char *argv[])
{
    int fd;
    sa();
    sleep(1000);
}

void sa()
{
   char *pi=new char[1024*1024*10];
   for(int i=0;i<4;++i) {
        for(int j=0;j<1024*1024;++j){
                *pi='o';
                pi++;
        }
   }
   int cnt;
   for(int i=0;i<6;++i) {
        for(int j=0;j<1024*1024;++j){
                cnt+=*pi;
                pi++;
        }
   }
   printf("%d",cnt);
}

$cat /proc/`pidof testprogram`/smaps

08838000-0885b000 rw-p 00000000 00:00 0          [heap]
Size:                140 kB
Rss:                  12 kB
Pss:                  12 kB
Shared_Clean:          0 kB
Shared_Dirty:          0 kB
Private_Clean:         0 kB
Private_Dirty:        12 kB
Referenced:           12 kB
Swap:                  0 kB
KernelPageSize:        4 kB
MMUPageSize:           4 kB
b6dcd000-b77d0000 rw-p 00000000 00:00 0
Size:              10252 kB
Rss:               10252 kB
Pss:                4108 kB
Shared_Clean:          0 kB
Shared_Dirty:          0 kB
Private_Clean:         0 kB
Private_Dirty:      4108 kB
Referenced:         4108 kB
Swap:                  0 kB
KernelPageSize:        4 kB
MMUPageSize:           4 kB

在这里，我发现pss等于Private_Dirty，但我想知道为什么.

Here I found pss equal to Private_Dirty, but I wonder why.

顺便说一句:smaps是否有详细的文献资料?

BTW: is there any detailed documention for smaps?

推荐答案

从 lwn.net 引用

来自 Linux内核文档，

/proc/PID/smaps是基于地图的扩展，显示了内存 每个流程映射的消耗.对于每个映射 是以下几行:

The /proc/PID/smaps is an extension based on maps, showing the memory consumption for each of the process's mappings. For each of mappings there is a series of lines such as the following:

08048000-080bc000 r-xp 00000000 03:02 13130      /bin/bash
Size:               1084 kB
Rss:                 892 kB
Pss:                 374 kB
Shared_Clean:        892 kB
Shared_Dirty:          0 kB
Private_Clean:         0 kB
Private_Dirty:         0 kB
Referenced:          892 kB
Anonymous:             0 kB
Swap:                  0 kB
KernelPageSize:        4 kB
MMUPageSize:           4 kB
Locked:              374 kB

此问题在Unix and Linux上，Stackexchange涵盖了几乎所有主题.请参阅Mat的出色回答，这肯定会清除您的所有疑问.

This Question on Unix and Linux Stackexchange covers almost the topic. See Mat's excellent answer which will surely clear all your doubts.

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