Huge pages Series 4, hugepages Series
From RedHat 6, OEL 6, SLES 11 and UEK2 kernels, Transparent HugePages is enabled by default to improve memory management.
The performance transparency page (Transparent HugePages) of is similar to that of the previous version. The main difference is that Transparent HugePages can be configured in real time,
The configuration does not need to be restarted to take effect;
Transparent HugePages mainly uses khugepaged thread, while previous large pages are pre-allocated during system startup;
However, oracle officially does not recommend that we use Transparent HugePages after RedHat 6, OEL 6, SLES 11 and UEK2 kernels ),
Transparent HugePages has some problems:
1. In the RAC environment, Transparent HugePages may cause abnormal node restart and performance problems;
2. In a single-host environment, Transparent HugePages may also cause some abnormal performance problems;
---- Take the Red Hat 6.0 as an example:
Method 1:
Enabled by default: [always] --- indicates that transparent large pages are enabled.
[Root @ rhel-6 redhat_transparent_hugepage] # cat/sys/kernel/mm/redhat_transparent_hugepage/enabled
[Always] madvise never
Disabled:
[Root @ rhel-6 redhat_transparent_hugepage] # cat/sys/kernel/mm/redhat_transparent_hugepage/enabled
Always madvise [never]
Method 2:
[Root @ The rhel-6 redhat_transparent_hugepage] # grep AnonHugePages/proc/meminfo
AnonHugePages: 143360 kB
If AnonHugePages> 0, a large transparent page is enabled;
---- How to disable transparent large pages:
Method 1 (priority ):
Add a record in/etc/grub. conf:
Transparent_hugepage = never
Then restart
Method 2:
Configure/etc/rc. local and then restart the server:
If test-f/sys/kernel/mm/redhat_transparent_hugepage/enabled; then
Echo never>/sys/kernel/mm/redhat_transparent_hugepage/enabled
Fi
If test-f/sys/kernel/mm/redhat_transparent_hugepage/defrag; then
Echo never>/sys/kernel/mm/redhat_transparent_hugepage/defrag
Fi
