如果有一个进程读取一个大文件并将其保存在其内存中(或只是一个malloced char*),并且该主进程是分叉的,如果子进程只从该内存(或char*)读取,则根据写时复制,不复制保存指针的内存,父和子共享相同的内存,直到其中任何一个尝试写入该内存,在这种情况下,进程会复制内存并进行更改那.
所以我的问题是,如果有一个拷贝写入实现,有没有办法知道孩子使用的内存量不与主进程共享？换句话说,子进程实际使用了多少内存,如果它使用来自某些读取调用的父内存？
top或ps命令只会给出孩子应该拥有的内存总量.(即假设孩子复制内存或指针中的数据.)
有没有办法获得CoW语义实际使用的数据量？
我/proc/[pid]/smaps 按照aix和Mat的建议经历过,但我发现的是很多空的文件.我试过这个命令来查找哪些文件中包含数据:tail -n 5 */smaps | less
我得到的o/p是
==> 1012/smaps <==
==> 1074/smaps <==
==> 10/smaps <==
==> 1148/smaps <==
==> 11862/smaps <==
==> 11/smaps <==
==> 1355/smaps <==
==> 1356/smaps <==
==> 1357/smaps <==
==> 1358/smaps <==
==> 1361/smaps <==
==> 13/smaps <==
==> 14900/smaps <==
==> 14/smaps <==
==> 1501/smaps <==
==> 15/smaps <==
==> 1684/smaps <==
==> 1685/smaps <==
==> 16/smaps <==
==> 17772/smaps <==
==> 17827/smaps <==
==> 17/smaps <==
==> 18490/smaps <==
==> 18/smaps <==
==> 1932/smaps <==
==> 1934/smaps <==
==> 19863/smaps <==
==> 19/smaps <==
==> 1/smaps <==
==> 20125/smaps <==
==> 20126/smaps <==
==> 20127/smaps <==
==> 20128/smaps <==
==> 20129/smaps <==
==> 20134/smaps <==
==> 20135/smaps <==
==> 20811/smaps <==
==> 20868/smaps <==
==> 20/smaps <==
==> 21116/smaps <==
==> 21774/smaps <==
==> 21/smaps <==
==> 22393/smaps <==
==> 22394/smaps <==
==> 22395/smaps <==
==> 22398/smaps <==
==> 22639/smaps <==
==> 22824/smaps <==
==> 22/smaps <==
==> 23009/smaps <==
==> 23058/smaps <==
==> 23059/smaps <==
Private_Dirty: 0 kB
Referenced: 0 kB
Swap: 0 kB
KernelPageSize: 4 kB
MMUPageSize: 4 kB
==> 23835/smaps <==
==> 23961/smaps <==
==> 23962/smaps <==
==> 23963/smaps <==
==> 23964/smaps <==
==> 23/smaps <==
==> 24180/smaps <==
==> 24268/smaps <==
==> 24467/smaps <==
==> 24/smaps <==
==> 252/smaps <==
==> 25352/smaps <==
==> 25435/smaps <==
==> 25/smaps <==
==> 26465/smaps <==
==> 26/smaps <==
==> 27884/smaps <==
==> 27/smaps <==
==> 28/smaps <==
==> 29/smaps <==
==> 2/smaps <==
==> 303/smaps <==
==> 30/smaps <==
==> 316/smaps <==
==> 31/smaps <==
==> 32074/smaps <==
==> 32076/smaps <==
==> 32112/smaps <==
Private_Dirty: 0 kB
Referenced: 0 kB
Swap: 0 kB
KernelPageSize: 4 kB
MMUPageSize: 4 kB
==> 32116/smaps <==
Private_Dirty: 0 kB
Referenced: 0 kB
Swap: 0 kB
KernelPageSize: 4 kB
MMUPageSize: 4 kB
==> 322/smaps <==
==> 32466/smaps <==
==> 32467/smaps <==
==> 32/smaps <==
==> 33/smaps <==
==> 34/smaps <==
==> 37/smaps <==
==> 38/smaps <==
==> 3991/smaps <==
==> 3992/smaps <==
==> 39/smaps <==
==> 3/smaps <==
==> 4005/smaps <==
==> 4006/smaps <==
==> 4007/smaps <==
==> 4008/smaps <==
==> 4009/smaps <==
==> 4010/smaps <==
==> 4018/smaps <==
==> 4029/smaps <==
==> 4038/smaps <==
==> 4044/smaps <==
==> 4045/smaps <==
==> 4046/smaps <==
==> 4053/smaps <==
==> 4054/smaps <==
==> 4055/smaps <==
==> 40/smaps <==
==> 41/smaps <==
==> 42/smaps <==
==> 4339/smaps <==
==> 435/smaps <==
==> 436/smaps <==
==> 43/smaps <==
==> 44/smaps <==
==> 45/smaps <==
==> 46/smaps <==
==> 47/smaps <==
==> 48/smaps <==
==> 49/smaps <==
==> 4/smaps <==
==> 50/smaps <==
==> 51/smaps <==
==> 52/smaps <==
==> 53/smaps <==
==> 54/smaps <==
==> 55/smaps <==
==> 56/smaps <==
==> 57/smaps <==
==> 58/smaps <==
==> 5988/smaps <==
==> 59/smaps <==
==> 5/smaps <==
==> 6058/smaps <==
==> 6059/smaps <==
Private_Dirty: 0 kB
Referenced: 0 kB
Swap: 0 kB
KernelPageSize: 4 kB
MMUPageSize: 4 kB
==> 60/smaps <==
==> 61/smaps <==
==> 62/smaps <==
==> 63/smaps <==
==> 64/smaps <==
==> 65/smaps <==
==> 66/smaps <==
==> 67/smaps <==
==> 68/smaps <==
==> 69/smaps <==
==> 6/smaps <==
==> 70/smaps <==
==> 71/smaps <==
==> 72/smaps <==
==> 73/smaps <==
==> 74/smaps <==
==> 771/smaps <==
==> 77/smaps <==
==> 782/smaps <==
==> 78/smaps <==
==> 79/smaps <==
==> 7/smaps <==
==> 80/smaps <==
==> 814/smaps <==
==> 819/smaps <==
==> 81/smaps <==
==> 82/smaps <==
==> 83/smaps <==
==> 84/smaps <==
==> 8654/smaps <==
==> 8655/smaps <==
==> 8656/smaps <==
==> 892/smaps <==
==> 8/smaps <==
==> 949/smaps <==
==> 950/smaps <==
==> 9/smaps <==
==> self/smaps <==
Private_Dirty: 0 kB
Referenced: 0 kB
Swap: 0 kB
KernelPageSize: 4 kB
MMUPageSize: 4 kB
那么我现在应该做什么呢？我的进程有空白的smaps正在运行.我如何得到那些pid的碎片？
我不知道有哪种工具可以提供这些信息,但您可以根据以下内容计算/proc/[pid]/smaps:
/proc/[pid]/smaps (since Linux 2.6.14)
This file shows 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: 464 kB
Rss: 424 kB
Shared_Clean: 424 kB
Shared_Dirty: 0 kB
Private_Clean: 0 kB
Private_Dirty: 0 kB
The first of these lines shows the same information as is displayed for
the mapping in /proc/[pid]/maps. The remaining lines show the size of
the mapping, the amount of the mapping that is currently resident in RAM,
the number of clean and dirty shared pages in the mapping, and the number
of clean and dirty private pages in the mapping.
有关详细信息,请参阅从中获取有关进程内存使用情况的信息/proc/pid/smaps.