我们有一个具有 64Gb RAM 的 CentOS5.8 服务器，正常运行大约 700Mb RAM 使用量。当我尝试tar -czf进入大约 22Gb 的存档时，页面缓存爬升到大约 22Gb，然后内核开始终止进程。最终，即使插入 USB 键盘，服务器也会变得无响应。
Fri Aug 5 11:00:01 CDT 2016
11:00:01 up 1 day, 2:06, 3 users, load average: 1.31, 1.71, 1.77
total used free shared buffers cached
Mem: 64237 22874 41363 0 0 22407
-/+ buffers/cache: 466 63771
Swap: 5279 0 5279
*****************************************************
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
534G 106G 401G 21% /
/dev/sda3 97M 13M 80M 14% /boot
tmpfs 32G 0 32G 0% /dev/shm
*****************************************************
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
r b swpd free buff cache si so bi bo in cs us sy id wa st
0 0 0 42355760 1020 22944876 0 0 33 19 7 6 0 0 100 0 0
0 0 0 42355760 1020 22945204 0 0 0 0 1003 2933 0 0 100 0 0
0 0 0 42355760 1020 22945220 0 0 0 0 1040 2963 0 0 100 0 0
0 0 0 42355760 1020 22945220 0 0 0 0 1004 2843 0 0 100 0 0
0 0 0 42355760 1020 22945220 0 0 0 0 1036 2915 0 0 100 0 0
和过程
root 993 0.0 0.0 S<s 00:00:00 /sbin/udevd -d
root 3578 0.0 0.0 S<Lsl 00:00:00 iscsiuio
root 3582 0.0 0.0 Ss 00:00:00 iscsid
root 3583 0.0 0.0 S<Ls 00:00:00 iscsid
root 4377 0.0 0.0 S<sl 00:00:00 auditd
root 4379 0.0 0.0 S<sl 00:00:00 \_ /sbin/audispd
root 4401 0.0 0.0 Ss 00:00:00 syslogd -m 0
root 4404 0.0 0.0 Ss 00:00:00 klogd -x
root 4540 0.0 0.0 Ss 00:00:00 irqbalance
rpc 4574 0.0 0.0 Ss 00:00:00 portmap
rpcuser 4655 0.0 0.0 Ss 00:00:00 rpc.statd
root 4683 0.0 0.0 Ss 00:00:00 rpc.idmapd
dbus 4705 0.0 0.0 Ss 00:00:00 dbus-daemon --system
root 4714 0.0 0.0 Ss 00:00:00 /usr/sbin/hcid
root 4720 0.0 0.0 Ss 00:00:00 /usr/sbin/sdpd
root 4786 0.0 0.0 S< 00:00:00 [krfcommd]
root 4823 0.0 0.0 Ssl 00:00:00 pcscd
root 4833 0.0 0.0 Ss 00:00:00 /usr/sbin/acpid
68 4846 0.0 0.0 Ss 00:00:01 hald
root 4847 0.0 0.0 S 00:00:00 \_ hald-runner
68 4855 0.0 0.0 S 00:00:00 \_ hald-addon-acpi: listening on acpid socket /var/run/acpid.socket
68 4862 0.0 0.0 S 00:00:00 \_ hald-addon-keyboard: listening on /dev/input/event0
68 4865 0.0 0.0 S 00:00:00 \_ hald-addon-keyboard: listening on /dev/input/event3
68 4868 0.0 0.0 S 00:00:00 \_ hald-addon-keyboard: listening on /dev/input/event2
root 4876 0.0 0.0 S 00:00:13 \_ hald-addon-storage: polling /dev/sr0
root 4878 0.0 0.0 S 00:00:00 \_ hald-addon-storage: polling /dev/sdb
root 4912 0.0 0.0 Ss 00:00:00 /usr/bin/hidd --server
root 4956 0.0 0.0 Ssl 00:00:00 automount
root 4973 0.0 0.0 Ss 00:00:00 ./hpiod
root 4978 0.0 0.0 S 00:00:00 /usr/bin/python ./hpssd.py
root 4991 0.0 0.0 Ss 00:00:00 /usr/sbin/sshd
root 12541 0.0 0.0 Ss 00:00:01 \_ sshd: root@pts/1
root 12543 0.0 0.0 Ss+ 00:00:00 | \_ -bash
root 13224 0.0 0.0 Ss 00:00:00 \_ sshd: metabk1 [priv]
metabk1 13226 0.0 0.0 S 00:00:00 \_ sshd: metabk1@pts/2
metabk1 13227 0.0 0.0 Ss+ 00:00:00 \_ -bash
root 5000 0.0 0.0 Ss 00:00:00 cupsd
root 5023 0.0 0.0 Ss 00:00:06 sendmail: accepting connections
smmsp 5031 0.0 0.0 Ss 00:00:00 sendmail: Queue runner@01:00:00 for /var/spool/clientmqueue
root 5041 0.0 0.0 Ss 00:00:00 gpm -m /dev/input/mice -t exps2
root 5050 0.0 0.0 Ss 00:00:00 crond
root 13284 0.0 0.0 S 00:00:00 \_ crond
root 13285 0.0 0.0 Ss 00:00:00 \_ /bin/sh -c /usr/local/bin/memmon.sh >> /var/log/memmon.txt
root 13286 0.0 0.0 S 00:00:00 \_ /bin/bash /usr/local/bin/memmon.sh
root 13292 0.0 0.0 R 00:00:00 \_ ps axfww -o ruser,pid,%cpu,%mem,stat,time,cmd
xfs 5079 0.0 0.0 Ss 00:00:00 xfs -droppriv -daemon
root 5096 0.0 0.0 Ss 00:00:00 /usr/sbin/atd
avahi 5135 0.0 0.0 Ss 00:00:00 avahi-daemon: running [RDVR.local]
avahi 5136 0.0 0.0 Ss 00:00:00 \_ avahi-daemon: chroot helper
root 5197 0.0 0.0 S 00:00:00 /usr/sbin/smartd -q never
root 5202 0.0 0.0 Ss+ 00:00:00 /sbin/mingetty tty1
root 5203 0.0 0.0 Ss 00:00:00 login -- root
root 13025 0.0 0.0 Ss 00:00:00 \_ -bash
root 13060 0.7 0.0 S+ 00:00:14 \_ top -M
root 5204 0.0 0.0 Ss+ 00:00:00 /sbin/mingetty tty3
root 5205 0.0 0.0 Ss+ 00:00:00 /sbin/mingetty tty4
root 5206 0.0 0.0 Ss+ 00:00:00 /sbin/mingetty tty5
root 5208 0.0 0.0 Ss+ 00:00:00 /sbin/mingetty tty6
root 5209 0.0 0.0 Ss 00:00:00 /usr/sbin/gdm-binary -nodaemon
root 13202 0.0 0.0 S 00:00:00 \_ /usr/sbin/gdm-binary -nodaemon
root 13203 0.6 0.0 Ss+ 00:00:02 \_ /usr/bin/Xorg :0 -br -audit 0 -auth /var/gdm/:0.Xauth -nolisten tcp vt7
gdm 13216 0.1 0.0 Ss 00:00:00 \_ /usr/libexec/gdmgreeter
root 5251 0.0 0.0 Sl 00:00:00 /usr/libexec/gdm-rh-security-token-helper
root 5257 0.0 0.0 SN 00:00:00 /usr/bin/python -tt /usr/sbin/yum-updatesd
root 13217 0.1 0.0 SN 00:00:00 \_ /usr/bin/python -tt /usr/libexec/yum-updatesd-helper --check --dbus
root 5259 0.0 0.0 SN 00:00:00 /usr/libexec/gam_server
最后是一些日志
DMESG:+Free pages: 42316788kB (42309540kB HighMem)
DMESG:+Active:28543 inactive:5737934 dirty:167940 writeback:0 unstable:0 free:10579197 slab:92371 mapped-file:5498 mapped-anon:21203 pagetables:727
DMESG:+DMA free:3588kB min:68kB low:84kB high:100kB active:12kB inactive:0kB present:16384kB pages_scanned:56981 all_unreclaimable? yes
DMESG:+lowmem_reserve[]: 0 0 880 65520
DMESG:+DMA32 free:0kB min:0kB low:0kB high:0kB active:0kB inactive:0kB present:0kB pages_scanned:0 all_unreclaimable? no
DMESG:+lowmem_reserve[]: 0 0 880 65520
DMESG:+Normal free:3660kB min:3756kB low:4692kB high:5632kB active:424kB inactive:44kB present:901120kB pages_scanned:621593 all_unreclaimable? yes
DMESG:+lowmem_reserve[]: 0 0 0 517120
DMESG:+HighMem free:42309540kB min:512kB low:69552kB high:138592kB active:113840kB inactive:22951588kB present:66191360kB pages_scanned:0 all_unreclaimable? no
DMESG:+lowmem_reserve[]: 0 0 0 0
DMESG:+DMA: 1*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 1*512kB 1*1024kB 1*2048kB 0*4096kB = 3588kB
DMESG:+DMA32: empty
DMESG:+Normal: 1*4kB 23*8kB 1*16kB 0*32kB 0*64kB 1*128kB 1*256kB 0*512kB 1*1024kB 1*2048kB 0*4096kB = 3660kB
DMESG:+HighMem: 1*4kB 0*8kB 0*16kB 1*32kB 0*64kB 1*128kB 1*256kB 1*512kB 1*1024kB 0*2048kB 10329*4096kB = 42309540kB
DMESG:+5745312 pagecache pages
DMESG:+Swap cache: add 0, delete 0, find 0/0, race 0+0
DMESG:+Free swap = 5406712kB
DMESG:+Total swap = 5406712kB
DMESG:+Free swap: 5406712kB
DMESG:+16777216 pages of RAM
DMESG:+16547840 pages of HIGHMEM
DMESG:+332415 reserved pages
DMESG:+5728571 pages shared
DMESG:+0 pages swap cached
DMESG:+167940 pages dirty
DMESG:+0 pages writeback
DMESG:+5498 pages mapped
DMESG:+92360 pages slab
DMESG:+727 pages pagetables
DMESG:+Out of memory: Killed process 12751, UID 503, (bash).
DMESG:+top invoked oom-killer: gfp_mask=0xd0, order=0, oomkilladj=0
DMESG:+ [<c045b9c3>] out_of_memory+0x72/0x1a3
DMESG:+ [<c045cf46>] __alloc_pages+0x24e/0x2cf
DMESG:+ [<c04a8ef3>] proc_info_read+0x0/0x96
DMESG:+ [<c045cfee>] __get_free_pages+0x27/0x33
DMESG:+ [<c04a8f2b>] proc_info_read+0x38/0x96
DMESG:+ [<c04a8ef3>] proc_info_read+0x0/0x96
DMESG:+ [<c04770e5>] vfs_read+0x9f/0x141
DMESG:+ [<c047756b>] sys_read+0x3c/0x63
DMESG:+ [<c0404f4b>] syscall_call+0x7/0xb
DMESG:+ =======================
您正在运行一个 32 位内核（以及一个过时的内核）。这意味着任何单个进程都被限制在略小于 4GB 的地址空间。该系统最初应该安装了 64 位操作系统。（当你使用它的时候，考虑一个更新的发行版。CentOS 5 很快就会停止支持。）