Linux进程虚拟内存和物理内存

先介绍几个基本概念:

SIZE: 进程使用的地址空间, 如果进程映射了100M的内存, 进程的地址空间将报告为100M内存. 事实上, 这个大小不是一个程序实际使用的内存数.

RSS: "Resident Set Size", 实际驻留"在内存中"的内存数. 不包括已经交换出去的代码. 举一个例子: 如果你有一个程序使用了100K内存, 操作系统交换出40K内存, 那么RSS为60K. RSS还包括了与其它进程共享的内存区域. 这些区域通常用于libc库等.

SHARE: RSS中与其它进程共享的内存部分大小.

VMSIZE: 一个进程占用的总的地址空间大小. 它包括了没有映射到内存中的页面.

Private RSS: 映射到内存中的页面, 这些页面仅由进程单独使用. 这也是我们最关心地方: 进程实际占用的内存数.

如何来查看Private RSS呢? /proc接口中每一个进程目录下的smaps提供了private rss信息. smaps是在2.6.16内核版本引进来的.

私有驻留内存数(Private RSS):
查看/proc/$pid/smaps

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下面我以本站使用的Linux AS5为例, 查看进程号1293(vmware-guestd, 本站使用的是一台基于vmware的客户虚拟机,)使用的Private RSS数.

CODE:

# cat /proc/ 1293 /smaps
00111000 - 00112000 rwxp 00111000 00 : 00 0
Size: 4 kB
Rss: 4 kB
Shared_Clean: 0 kB
Shared_Dirty: 0 kB
Private_Clean: 0 kB
Private_Dirty: 4 kB
0050e000-0050f000 rwxp 0050e000 00 : 00 0
Size: 4 kB
Rss: 0 kB
Shared_Clean: 0 kB
Shared_Dirty: 0 kB
Private_Clean: 0 kB
Private_Dirty: 0 kB
0051a000-0051b000 r-xp 0051a000 00 : 00 0 [ vdso ]
Size: 4 kB
Rss: 4 kB
Shared_Clean: 4 kB
Shared_Dirty: 0 kB
Private_Clean: 0 kB
Private_Dirty: 0 kB
0051b000- 00534000 r-xp 00000000 fd: 00 194898 /lib/ld- 2 . 4 . so
Size: 100 kB
Rss: 0 kB
Shared_Clean: 0 kB
Shared_Dirty: 0 kB
Private_Clean: 0 kB
Private_Dirty: 0 kB
00534000 - 00535000 r-xp 00018000 fd: 00 194898 /lib/ld- 2 . 4 . so
Size: 4 kB
Rss: 0 kB
Shared_Clean: 0 kB
Shared_Dirty: 0 kB
Private_Clean: 0 kB
Private_Dirty: 0 kB
00535000 - 00536000 rwxp 00019000 fd: 00 194898 /lib/ld- 2 . 4 . so
Size: 4 kB
Rss: 0 kB
Shared_Clean: 0 kB
Shared_Dirty: 0 kB
Private_Clean: 0 kB
Private_Dirty: 0 kB
00538000 - 00665000 r-xp 00000000 fd: 00 194905 /lib/libc- 2 . 4 . so
Size: 1204 kB
Rss: 212 kB
Shared_Clean: 204 kB
Shared_Dirty: 0 kB
Private_Clean: 8 kB
Private_Dirty: 0 kB
00665000 - 00667000 r-xp 0012d000 fd: 00 194905 /lib/libc- 2 . 4 . so
Size: 8 kB
Rss: 8 kB
Shared_Clean: 4 kB
Shared_Dirty: 0 kB
Private_Clean: 0 kB
Private_Dirty: 4 kB
00667000 - 00668000 rwxp 0012f000 fd: 00 194905 /lib/libc- 2 . 4 . so
Size: 4 kB
Rss: 4 kB
Shared_Clean: 0 kB
Shared_Dirty: 0 kB
Private_Clean: 0 kB
Private_Dirty: 4 kB
00668000 -0066b000 rwxp 00668000 00 : 00 0
Size: 12 kB
Rss: 8 kB
Shared_Clean: 0 kB
Shared_Dirty: 0 kB
Private_Clean: 0 kB
Private_Dirty: 8 kB
08047000 - 08062000 r-xp 00000000 fd: 00 292327 /usr/sbin/vmware-guestd
Size: 108 kB
Rss: 64 kB
Shared_Clean: 0 kB
Shared_Dirty: 0 kB
Private_Clean: 64 kB
Private_Dirty: 0 kB
08062000 - 08063000 rwxp 0001a000 fd: 00 292327 /usr/sbin/vmware-guestd
Size: 4 kB
Rss: 4 kB
Shared_Clean: 0 kB
Shared_Dirty: 0 kB
Private_Clean: 0 kB
Private_Dirty: 4 kB
08063000 - 08068000 rwxp 08063000 00 : 00 0
Size: 20 kB
Rss: 12 kB
Shared_Clean: 0 kB
Shared_Dirty: 0 kB
Private_Clean: 0 kB
Private_Dirty: 12 kB
08385000 - 08886000 rwxp 08385000 00 : 00 0 [ heap ]
Size: 5124 kB
Rss: 5080 kB
Shared_Clean: 0 kB
Shared_Dirty: 0 kB
Private_Clean: 0 kB
Private_Dirty: 5080 kB
bfeb2000-bfec7000 rwxp bfeb2000 00 : 00 0 [ stack ]
Size: 84 kB
Rss: 12 kB
Shared_Clean: 0 kB
Shared_Dirty: 0 kB
Private_Clean: 0 kB
Private_Dirty: 12 kB

上面我们看到从smaps看不太方便, 推荐使用Ben Maurer写的perl脚本:

#!/usr/bin/perl # Copyright Ben Maurer # you can distribute this under the MIT/X11 License use Linux::Smaps; my $pid=shift @ARGV; unless ($pid) { print "./smem.pl <pid>\n"; exit 1; } my $map=Linux::Smaps->new($pid); my @VMAs = $map->vmas; format STDOUT = VMSIZE: @######## kb $map->size RSS: @######## kb total $map->rss @######## kb shared $map->shared_clean + $map->shared_dirty @######## kb private clean $map->private_clean @######## kb private dirty $map->private_dirty . write; printPrivateMappings (); printSharedMappings (); sub sharedMappings () { return grep { ($_->shared_clean + $_->shared_dirty) > 0 } @VMAs; } sub privateMappings () { return grep { ($_->private_clean + $_->private_dirty) > 0 } @VMAs; } sub printPrivateMappings () { $TYPE = "PRIVATE MAPPINGS"; $^ = 'SECTION_HEADER'; $~ = 'SECTION_ITEM'; $- = 0; $= = 100000000; foreach $vma (sort {-($a->private_dirty <=> $b->private_dirty)} privateMappings ()) { $size = $vma->size; $dirty = $vma->private_dirty; $clean = $vma->private_clean; $file = $vma->file_name; write; } } sub printSharedMappings () { $TYPE = "SHARED MAPPINGS"; $^ = 'SECTION_HEADER'; $~ = 'SECTION_ITEM'; $- = 0; $= = 100000000; foreach $vma (sort {-(($a->shared_clean + $a->shared_dirty) <=> ($b->shared_clean + $b->shared_dirty))} sharedMappings ()) { $size = $vma->size; $dirty = $vma->shared_dirty; $clean = $vma->shared_clean; $file = $vma->file_name; write; } } format SECTION_HEADER = @<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< $TYPE @>>>>>>>>>> @>>>>>>>>>> @>>>>>>>>> @<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< "vmsize" "rss clean" "rss dirty" "file" . format SECTION_ITEM = @####### kb @####### kb @####### kb @<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< $size $clean $dirty $file .

下面是由seme.pl脚本解析的smaps数据:

首先安装Linux::Smaps模块:
perl -MCPAN -e 'install Linux::Smaps'//需要网络，如无法上网，则可下载压缩包解压到 /root

然后用seme.pl解析1293进程的Smaps数据:

CODE:

# ./smem. pl 1293
VMSIZE: 7200 kb
RSS: 1052 kb total
192 kb shared
100 kb private clean
760 kb private dirty
PRIVATE MAPPINGS
vmsize rss clean rss dirty file
5636 kb 8 kb 724 kb [ heap ]
84 kb 0 kb 12 kb [ stack ]
4 kb 0 kb 4 kb
8 kb 0 kb 4 kb /lib/libc- 2 . 4 . so
4 kb 0 kb 4 kb /lib/libc- 2 . 4 . so
12 kb 4 kb 4 kb
4 kb 0 kb 4 kb /usr/sbin/vmware-guestd
20 kb 8 kb 4 kb
1204 kb 16 kb 0 kb /lib/libc- 2 . 4 . so
108 kb 64 kb 0 kb /usr/sbin/vmware-guestd
SHARED MAPPINGS
vmsize rss clean rss dirty file
1204 kb 188 kb 0 kb /lib/libc-2.4.so
4 kb 4 kb 0 kb [vdso]

从上面看到rss大小被分成了两个部分: private(私有)和shared(共享).
private rss就是我们最关心的进程实际占用的内存数.

http://hi.baidu.com/youngtao/blog/item/70621d83c72933a50cf4d29a.html

Linux进程虚拟内存和物理内存

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