HugePages and resident memory

[Yong Huang]

`top' RES shows resident memory for each process. On a RHEL4 box where HugePages is enabled and used by Oracle database, the numbers under RES for Oracle processes are very close to those under VIRT (virtual memory). But on a RHEL5 box similarly configured, the RES number is way much smaller (mmon is usually the most memory-hungry process of oracle):

$ top
...
 VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
8914m 356m  40m S    0  2.2 101:35.65 ora_mmon_oracp31

$ grep -i huge /proc/meminfo
HugePages_Total:  5120
HugePages_Free:    968
HugePages_Rsvd:      8
Hugepagesize:     2048 kB
$ grep memlock /etc/security/limits.conf
oracle              soft    memlock 8590000
oracle              hard    memlock 8590000
$ uname -a
Linux <hostname> 2.6.18-92.1.13.el5 #1 SMP Thu Sep 4 03:51:21 EDT 2008 x86_64 x86_64 x86_64 GNU/Linux
$ cat /etc/redhat-release
Red Hat Enterprise Linux Server release 5.2 (Tikanga)

top is version 3.2.7 instead of 3.2.3 as on RHEL4. But I doubt it's because of top version. Is there any change made to HugePages or I didn't configure it correctly? Or it's just a matter of top display?

Yong Huang