内存被什么占用了？同一个程序，阿里云 2G 内存程序因内存不足被 kill， do 512M VPS 整个系统只占用 240M。

2016-09-15 20:55:08 +08:00
 gamexg

一个 go 程序，在阿里云 ubuntu14.04 运行的。 free 显示占用了 1.7G 内存，但是我实在找不到这 1.7G 内存被什么占用了...

root@iZ62hgc3hpoZ:~# free -h
             total       used       free     shared    buffers     cached
Mem:          2.0G       1.7G       215M       412K       3.1M        15M
-/+ buffers/cache:       1.7G       234M
Swap:           0B         0B         0B

root@iZ62hgc3hpoZ:~# ps auxw|head -1;ps auxw|sort -rn -k4|head -10 
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root      2096  0.7  3.7 798244 76988 pts/0    Sl+  20:33   0:01 ./forward
root      2066  0.0  0.1  22284  2944 pts/0    Ss   20:31   0:00 -bash
root      1950  0.0  0.1  22292  2404 pts/3    Ss   19:07   0:00 -bash
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
syslog     368  0.0  0.0 255840   688 ?        Ssl  17:57   0:00 rsyslogd
root       924  0.0  0.0  15816   160 tty1     Ss+  17:58   0:00 /sbin/getty -8 38400 tty1
root         9  0.0  0.0      0     0 ?        S    17:57   0:00 [rcu_bh]
root         8  0.0  0.0      0     0 ?        S    17:57   0:00 [rcuos/0]
root       777  0.0  0.0  23652   448 ?        Ss   17:57   0:00 cron
root       774  0.0  0.0  61376   684 ?        Ss   17:57   0:00 /usr/sbin/sshd -D


mmon 命令输出:
lnmonq14gqqqqqq[H for help]qqqHostname=iZ62hgc3hpoZqRefresh= 2secs qqq20:36.11qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqk
x Memory Stats qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqx
x                RAM     High      Low     Swap    Page Size=4 KB                                                                            x
x Total MB      2001.9     -0.0     -0.0      0.0                                                                                            x
x Free  MB       119.2     -0.0     -0.0      0.0                                                                                            x
x Free Percent     6.0%   100.0%   100.0%     0.0%                                                                                           x
x             MB                  MB                  MB                                                                                     x
x                      Cached=   102.6     Active=   108.2                                                                                   x
x Buffers=     5.0 Swapcached=     0.0  Inactive =    91.3                                                                                   x
x Dirty  =     0.0 Writeback =     0.0  Mapped   =     4.8                                                                                   x
x Slab   =   101.5 Commit_AS =   153.1 PageTables=     2.6                                                                                   x
xqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqx


root@iZ62hgc3hpoZ:~# cat /proc/meminfo 
MemTotal:        2049904 kB
MemFree:          124512 kB
Buffers:            5412 kB
Cached:           105412 kB
SwapCached:            0 kB
Active:           107488 kB
Inactive:          94048 kB
Active(anon):      90768 kB
Inactive(anon):      396 kB
Active(file):      16720 kB
Inactive(file):    93652 kB
Unevictable:           0 kB
Mlocked:               0 kB
SwapTotal:             0 kB
SwapFree:              0 kB
Dirty:                 0 kB
Writeback:             0 kB
AnonPages:         90796 kB
Mapped:             4696 kB
Shmem:               412 kB
Slab:             103948 kB
SReclaimable:      30260 kB
SUnreclaim:        73688 kB
KernelStack:         688 kB
PageTables:         2616 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:     1024952 kB
Committed_AS:     156768 kB
VmallocTotal:   34359738367 kB
VmallocUsed:     1697480 kB
VmallocChunk:   34358029192 kB
HardwareCorrupted:     0 kB
AnonHugePages:     36864 kB
HugePages_Total:       0
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB
DirectMap4k:       32640 kB
DirectMap2M:     2064384 kB
DirectMap1G:           0 kB

slabtop 命令输出：
 Active / Total Objects (% used)    : 379789 / 382445 (99.3%)
 Active / Total Slabs (% used)      : 14435 / 14435 (100.0%)
 Active / Total Caches (% used)     : 64 / 96 (66.7%)
 Active / Total Size (% used)       : 100656.00K / 101729.76K (98.9%)
 Minimum / Average / Maximum Object : 0.01K / 0.27K / 8.00K

  OBJS ACTIVE  USE OBJ SIZE  SLABS OBJ/SLAB CACHE SIZE NAME                   
 73728  73480  99%    0.06K   1152       64      4608K kmalloc-64
 47712  47712 100%    0.12K   1491       32      5964K kmalloc-128
 32403  32086  99%    0.19K   1543       21      6172K dentry
 26859  26346  98%    0.19K   1279       21      5116K kmalloc-192
 25856  25856 100%    0.02K    101      256       404K kmalloc-16
 25216  25216 100%    0.03K    197      128       788K kmalloc-32
 24976  24976 100%    0.07K    446       56      1784K Acpi-ParseExt
 24432  24147  98%    0.25K   1527       16      6108K kmalloc-256
 23496  23496 100%    0.62K   1958       12     15664K sock_inode_cache
 23436  23436 100%    1.75K   2604        9     41664K TCP
 15408  15408 100%    0.11K    428       36      1712K sysfs_dir_cache
 12792  12426  97%    0.10K    328       39      1312K buffer_head
  6426   5980  93%    0.57K    459       14      3672K inode_cache
  3584   3584 100%    0.01K      7      512        28K kmalloc-8
  2380   2380 100%    0.05K     28       85       112K shared_policy_node
  2288   2207  96%    0.96K    286        8      2288K ext4_inode_cache
  1512   1512 100%    0.07K     27       56       108K anon_vma
  1428   1428 100%    0.04K     14      102        56K ext4_extent_status
  1008   1008 100%    0.09K     24       42        96K kmalloc-96
  1036    873  84%    0.55K     74       14       592K radix_tree_node
   792    792 100%    0.66K     66       12       528K shmem_inode_cache
   544    501  92%    1.00K     68        8       544K kmalloc-1024
   560    496  88%    0.50K     70        8       280K kmalloc-512
   492    431  87%    0.63K     41       12       328K proc_inode_cache
 24976  24976 100%    0.07K    446       56      1784K Acpi-ParseExt
    56     56 100%    0.07K      1       56         4K ext4_io_end
   153    153 100%    0.08K      3       51        12K Acpi-State
     0      0   0%    0.09K      0       46         0K ext4_xattr

root@iZ62hgc3hpoZ:~#  echo `cat /proc/slabinfo |awk 'BEGIN{sum=0;}{sum=sum+$3*$4;}END{print sum/1024/1024}'` MB
99.3455 MB
root@iZ62hgc3hpoZ:~# echo `grep PageTables /proc/meminfo | awk '{print $2}'` KB
2224 KB
365 次点击
所在节点    VPS
4 条回复
selinaspy
2016-09-15 20:57:10 +08:00
有种东西叫动态内存
gamexg
2016-09-15 21:06:00 +08:00
@selinaspy 不明白什么意思，指的应用程序突发内存占用？
gamexg
2016-09-15 21:17:55 +08:00
都怀疑是不是 OpenVZ 的那个内存统计问题，但是阿里云使用的是 xen 啊
gamexg
2016-09-15 21:50:24 +08:00
确认了问题，是 tcp 协议栈占用的内存，一个最大队列大小设置的太大了。
但是奇葩的是在其他平台做过相同的配置，却没有出现这个问题。

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